WO1997038397A1 - Method for processing images representing a painting - Google Patents

Method for processing images representing a painting Download PDF

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Publication number
WO1997038397A1
WO1997038397A1 PCT/FR1997/000608 FR9700608W WO9738397A1 WO 1997038397 A1 WO1997038397 A1 WO 1997038397A1 FR 9700608 W FR9700608 W FR 9700608W WO 9738397 A1 WO9738397 A1 WO 9738397A1
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WIPO (PCT)
Prior art keywords
radiation
virtual image
visible
colors
image
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Application number
PCT/FR1997/000608
Other languages
French (fr)
Inventor
Albert Jobbe-Duval
Original Assignee
Cabane, Jobbe-Duval
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Application filed by Cabane, Jobbe-Duval filed Critical Cabane, Jobbe-Duval
Publication of WO1997038397A1 publication Critical patent/WO1997038397A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B44—DECORATIVE ARTS
    • B44D—PAINTING OR ARTISTIC DRAWING, NOT OTHERWISE PROVIDED FOR; PRESERVING PAINTINGS; SURFACE TREATMENT TO OBTAIN SPECIAL ARTISTIC SURFACE EFFECTS OR FINISHES
    • B44D7/00—Preserving paintings, e.g. by varnishing
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T5/00—Image enhancement or restoration
    • G06T5/50—Image enhancement or restoration using two or more images, e.g. averaging or subtraction

Definitions

  • the present invention relates to a method for processing images representative of a pictorial work.
  • the invention is particularly applicable to the analysis of the constituent parts of such works.
  • the object of the present invention is to propose a method of processing images representative of a pictorial work by emission of electromagnetic radiation in the direction of said work, which makes it possible to obtain at least one virtual image whose appearance and colors are close to those of said work and which gathers the information provided by the invisible rays mentioned above.
  • the method according to the invention consists in taking at least three photographs of said work from the same angle of view and corresponding respectively to radiation of different wavelengths, which belong to the visible and invisible spectra, and to them. combine them so as to obtain at least one virtual image based on fundamental colors, the colors of said or each virtual image being respectively associated with said radiations in the same order of wavelengths.
  • the method then consists in making the difference, for at least each fundamental color, of said virtual image and of a photograph taken by means of visible radiation and to combine between them the difference photographs respectively obtained, so as to obtain a virtual image of difference based on fundamental colors
  • the method consists in obtaining two virtual images based on fundamental colors, the first in a first range of wavelengths extending beyond the visible range and the second in a second range of lengths d wave including said first domain, so that the radiation used to obtain each of the two virtual images have in common a radiation located in the visible domain.
  • said method consists in obtaining a first virtual image based on fundamental colors, the colors of said first image being respectively associated with photographs in shades of gray taken in the visible domain and on both sides. other of the latter, to process said first virtual image based on fundamental colors so that it consists of shades of gray, and to combine the virtual image obtained with at least two additional photographs whose respective radiations overflow and other of the domain used for obtaining said first virtual image, so as to obtain said second virtual image which is based on fundamental colors and whose colors are respectively associated with said additional radiations in the same order of lengths wave.
  • the method then consists in making the difference, for at least each fundamental color, of said second virtual image and of said first virtual image and in combining together the difference photographs respectively obtained, so to obtain a virtual image of difference based on fundamental colors.
  • said radiations respectively associated with the fundamental colors red, green and blue consist of red radiation under ultraviolet fluorescence, of visible green radiation and of blue radiation under ultraviolet fluorescence
  • said radiation respectively associated with the fundamental colors red, green and blue consist of infrared radiation, of green radiation under ultraviolet fluorescence and of visible blue radiation
  • said radiation respectively associated with the fundamental colors red, green and blue are consisting of infrared radiation, green visible radiation and ultraviolet radiation
  • said radiations respectively associated with the fundamental colors red, green and blue consist of infrared radiation, green visible radiation and blue radiation under ultraviolet fluorescence
  • Fig 1 is a simplified diagram of the image processing method representative of a pictorial work according to the invention
  • Fig 2 is a simplified diagram illustrating the method of obtaining a virtual image obtained by the method of processing d images according to the invention
  • the image processing method according to the invention essentially consists in photographing the pictorial work 10 to be analyzed under different electromagnetic radiation 20, then in digitizing and processing the photographs obtained corresponding to said radiation 20 so as to obtain at least one virtual image 30, 30 ', 30 "whose appearance is close to that of the work 10 observed in () real light
  • the first step of photographing the work 10 is implemented by means of a camera 40 making it possible to take non-white pictures in several areas of the electromagnetic spectrum located outside the visible area, including for example the infrared and ultraviolet areas , as well as color views in the visible domain
  • the camera 40 is provided with interference filters 41, 42, 43, 44 and 45, respectively designed to retain infrared (IR), red (R) radiation, green (V), blue (B) and ultraviolet (UV)
  • the camera 40 may be in front of or behind the work 10, depending on whether one wishes to observe the reflected or transmitted part of the incident radiation 20 by said work 10
  • ten photographs of the work 10 were captured, the latter being lit by means of different electromagnetic radiation 20:
  • Photograph 1 infrared (wavelength 1100 nm)
  • Photograph 2 infrared (wavelength 960 nm)
  • Ultraviolet photography 9 for photography of green light emitted by fluorescence Ultraviolet photography 9 for photography of blue light emitted by fluorescence
  • each radiation 20 corresponds to a unique set of shades of gray on each black and white photograph obtained.
  • the second step of digitizing each photograph is implemented by a computer 60 equipped with an acquisition card for the photographs taken by the camera 40, which is connected to said computer 60
  • the third step for processing the photographs obtained is implemented by means of image processing software provided on said computer 60.
  • the processing step consists first of all of wedging the photographs in relation to each other, so that the virtual image or images 30, 30 ′, 30 " 97/38397 PC17FR97 / 00608
  • the processing step then consists of a phase of combining at least three photographs respectively taken under determined radiation, so as to obtain a virtual image 30 (IM.V in FIG. 2) in color, each elementary point of which is then constituted by the combination of the fundamental color signals red, green, blue (RGB), or else cyan, magenta, yellow (CMY)
  • RGB fundamental color signals
  • CML magenta, yellow
  • Example 1 The photographs used for obtaining said virtual image 30 based on red, green and blue are photographs 8, 5 and 10 respectively.
  • the image Virtual 30 obtained in particular makes it possible to highlight all of the repaintings of work 10.
  • Example 2 The photographs used to obtain said virtual image 30 based on red, green and blue are photographs 3, 9 and 6 respectively.
  • the virtual image 30 obtained in particular makes it possible to highlight the old repaintings of work 10.
  • EXAMPLE 3 The photographs used to obtain said virtual image 30 based on red, green and blue are photographs 3, 5 and 7 respectively.
  • the virtual image 30 obtained in particular makes it possible to analyze details of the image with precision. work 10, such as a signature
  • EXAMPLE 4 The photographs used to obtain said virtual image 30 based on red, green and blue are photographs 3, 5 and 10 respectively.
  • the virtual image 30 obtained in particular makes it possible to analyze details of the image with precision. work 10, such as a signature
  • the virtual image 30 obtained makes it possible to gather a great deal of information relating to the different stages making up the work. In the case of a painting, it is thus possible to quickly identify the repainted parts, the alterations suffered by the canvas, the gaps, etc.
  • each elementary point which it contains comprises the aforementioned fundamental colors, which are respectively associated with said rays 20 in the same order of wavelengths ( ⁇ ), said rays 20 belonging to a more extensive domain that the visible area
  • the processing step then consists in making the difference, for at least each fundamental color, of said virtual image 30 and of a photograph taken by means of visible radiation 20 and in combining together the difference photographs respectively obtained, so as to obtain a virtual difference image based on fundamental colors Said virtual difference image allows to visualize precisely the details of the virtual image 30 which are not contained in the visible image.
  • two virtual images 30 ′ are produced and
  • the first virtual image 30 encodes a first wavelength domain extending beyond the visible domain
  • the second virtual image 30 it encompasses a second length domain wave including said first domain, so that the radiation 20 used to obtain each of the two virtual images 30 ′ and 30 ′′ have in common a radiation 20 located in the visible domain.
  • the radiation 20 used can by example be chosen from those who are at the origin of the ten aforementioned photographs.
  • the rays 20 selected to give each virtual image 30 ′ or 30 ′′ are, for three of them, respectively associated with the colors red, green, blue (or magenta, yellow, cyan) according to the order decreasing wavelengths.
  • the organization of the visible light spectrum therefore serves as a reference.
  • the image used as the basis for the analysis is the one with the widest spectrum, that is to say the said second 30 "virtual image.
  • the difference is then made, for at least each fundamental color, of said second virtual image 30 "and of said first virtual image 30 'and the difference photographs respectively obtained between them are combined, so as to obtain a virtual image of difference based on fundamental colors
  • the latter makes it possible to view the details of said second virtual image 30 ′′ which are not contained in said first virtual image 30 ′.
  • the second virtual image 30 " is then compared to the first 30 ', in order to correct the differences by appropriate adjustments and corrections.
  • said first virtual image 30 ′ is obtained in the following manner.
  • a photograph taken in the visible range is combined which is treated so as to consist of shades of gray and at least two photographs taken on either side of said visible range on the electromagnetic spectrum, by example in the near infrared and near ultraviolet domains
  • the first virtual image 30 ′ is thus obtained, which is based on colors resulting from a combination of RGB signals.
  • said first virtual image 30 ′ is processed in color, so as to obtain a virtual image which is made up of shades of gray corresponding to combinations of said colors R, G, B.
  • this virtual black and white image is then combined with at least two additional photographs, also in black and white, so as to obtain said second virtual image 30 "based on RGB signals.
  • additional photographs are respectively taken under radiation satisfying the following condition.
  • the radiation used for said additional photographs will be respectively characterized by a wavelength greater than 850 nm and by a wavelength less than 340 nm
  • the radiation used for these additional photographs belongs respectively to the fields of far infrared and far ultraviolet.
  • first virtual image 30 ′ and the additional photographs taken under far infrared and ultraviolet radiation which have been selected to give the second virtual image 30 ′′ are, for three of them, respectively associated with the fundamental colors green, red and blue, i.e. keeping the same wavelength order for visible and invisible radiation
  • the difference is then made, for at least each fundamental color R, G, B, of this second virtual image 30 "and of said first virtual image 30 ', then the photographs of them are combined. difference respectively obtained so as to obtain a virtual image of difference based on fundamental colors.
  • the differences between the 30 'and 30' virtual images are also corrected by appropriate adjustments.
  • this second embodiment is not limited to obtaining two virtual images 30 ′ and 30 ′′ which are compared with one another or else to a photograph of the work 10 in visible light.
  • the method according to this second mode could also be implemented by means of more than two virtual images
  • the virtual image in RGB of rank n (n> 2) would be obtained by the combination of the virtual image in RGB of rank n - 1, treated so as to be formed only of shades of gray, and at least two additional photographs taken under radiation extending beyond the domain which is delimited by the photographs having served to obtain said virtual image of rank n- 1 (we could for example use X or Gamma rays instead of ultraviolet rays)
  • the virtual image of rank n- 1 would be associated with the fundamental green color for obtaining the virtual image of rank n
  • a first condition necessary for implementing the method according to the invention is that the work 10 is such that it can give rise to at least two shades of gray belonging to the same material, on each photograph taken in black and white.
  • a second condition is that the photographs obtained can be set to the same dimension and that they have all been taken from the same angle of view.
  • a third condition is of course that the material of the work 10 is sensitive to the different radiations used of the electromagnetic spectrum. It will be noted that the image processing method according to the invention is all the more advantageous the higher the number of distinct shades of gray. As an indication, there are up to a thousand for certain images studied in medicine.
  • the method according to the invention could consist in taking more than three photographs in the visible and invisible fields in each of the abovementioned embodiments, provided that the rays 20 under which said photographs are taken respectively are associated with the colors of the virtual image 30 , 30 ', 30 "in the same order of wavelengths.

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  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
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Abstract

A method for processing images representing a painting using the transmission of electromagnetic rays (20) in the direction of a painting (10) includes the steps of taking at least three photographs of said painting (10) from the same angle of view, corresponding to rays (20) of different wavelengths respectively, said wavelengths belonging to the visible and invisible spectra, and combining them so as to obtain one or more virtual images (30, 30', 30'') based on primary colours, the colours of each virtual image (30, 30', 30'') being associated respectively with said rays (20) in the same wavelength order. The invention is particularly useful for analysing the constituent parts of such paintings.

Description

Procédé de traitement d'images représentatives d'une oeuvre picturale. Process for processing images representative of a pictorial work.
La présente invention concerne un procédé de traitement d'images représentatives d'une oeuvre picturale. L'invention s'applique notamment à l'analyse des parties constitutives de telles oeuvres.The present invention relates to a method for processing images representative of a pictorial work. The invention is particularly applicable to the analysis of the constituent parts of such works.
Il est connu d'utiliser à des fins d'analyse, pour divers rayonnements, les différences des caractéristiques de transmission et de réflexion de la matière constituant une oeuvre picturale. Les renseignements ainsi fournis sont différents quand on passe d'un rayonnement à un autre.It is known to use for analysis purposes, for various radiations, the differences in the transmission and reflection characteristics of the material constituting a pictorial work. The information thus provided is different when going from one radiation to another.
Par exemple, l'éclairage d'un tableau sous rayonnement infrarouge révèle parfois des zones plus noires que d'autres. De telles zones correspondent souvent à des lacunes sur la toile, qui indiquent par leur géométrie l'histoire des dégradations du tableau.For example, lighting a painting under infrared radiation sometimes reveals areas that are darker than others. Such areas often correspond to gaps on the canvas, which indicate by their geometry the history of the degradations of the painting.
L'analyse de la fluorescence de Wood émise par un tableau éclairé au moyen d'un rayonnement ultraviolet révèle parfois des taches sombres disséminées sur la surface de la toile, ou bien un aspect laiteux de ladite surface. Ces taches peuvent matérialiser des réintégrations récentes. Quant à l'aspect laiteux, il est en général dû à une altération naturelle du vernis recouvrant la peinture.Analysis of the fluorescence of Wood emitted by a table lit by means of ultraviolet radiation sometimes reveals dark spots scattered on the surface of the canvas, or a milky appearance of said surface. These spots can materialize recent reintegrations. As for the milky appearance, it is generally due to a natural alteration of the varnish covering the paint.
On observe que certaines lacunes, évidentes sous rayonnement infrarouge, demeurent invisibles ou sont peu visibles sous rayonnement ultraviolet. De la même manière, certaines altérations ou repeints de la toile ne sont révélés que sous un rayonnement correspondant à un domaine spectral particulier.It is observed that certain gaps, evident under infrared radiation, remain invisible or are hardly visible under ultraviolet radiation. Of the same In this way, certain alterations or repaintings of the canvas are only revealed under radiation corresponding to a particular spectral domain.
On a cherché à rendre compte de la relation existant entre les informations contenues dans deux photographies d'un tableau, lesquelles correspondent respectivement à des expositions de celui-ci à deux rayonnements, l'un visible et l'autre invisible. On peut par exemple citer le document IEEE extrait de la revue scientifique "Transactions On Acoustics, Speech, and Signal Processing", vol 38, N° 4, 1 avril 1990, pages 695-704 (par Heitz F et al.), dont le titre est "Event Détection in Multisource Imaging: Application to Fine Arts Painting Analysis." Ce document mentionne notamment l'utilisation de deux photographies, l'une prise dans le domaine visible et l'autre sous rayons X, pour l'obtention par combinaison d'une image virtuelle prévue pour témoigner des différences structurelles qui apparaissent suite à l'examen séparé desdites deux images réelles. La combinaison précitée des deux images réelles est mise en oeuvre par un algorithme suivi d'un traitement informatique.We sought to account for the relationship between the information contained in two photographs of a painting, which correspond respectively to exposures of the latter to two radiations, one visible and the other invisible. One can for example quote the document IEEE extracted from the scientific review "Transactions On Acoustics, Speech, and Signal Processing", vol 38, N ° 4, April 1, 1990, pages 695-704 (by Heitz F et al.), Of which the title is "Event Detection in Multisource Imaging: Application to Fine Arts Painting Analysis." This document mentions in particular the use of two photographs, one taken in the visible field and the other under X-rays, to obtain by combination of a virtual image intended to testify to the structural differences which appear following the separate examination of said two real images. The aforementioned combination of the two real images is implemented by an algorithm followed by computer processing.
Un inconvénient majeur de ce procédé de traitement d'images est que ladite image virtuelle ne présente pas un aspect et des couleurs qui sont vraiment proches de ceux du tableau original. Il en résulte que les renseignements que cette image virtuelle est censée fournir ne sont pas facilement accessibles. Le but de la présente invention est de proposer un procédé de traitement d'images représentatives d'une oeuvre picturale par émission de rayonnements électromagnétiques en direction de ladite oeuvre, qui permette d'obtenir au moins une image virtuelle dont l'aspect et les couleurs soient proches de ceux de ladite oeuvre et qui rassemble les renseignements fournis par les rayonnements invisibles précités. A cet effet, le procédé selon l'invention consiste à prendre au moins trois photographies de ladite oeuvre sous le même angle de vue et correspondant respectivement à des rayonnements de longueurs d'ondes différentes, lesquelles appartiennent aux spectres visible et invisible, et à les combiner entre elles de manière à obtenir au moins une image virtuelle à base de couleurs fondamentales, les couleurs de ladite ou chaque image virtuelle étant respectivement associées auxdits rayonnements dans le même ordre de longueurs d'onde.A major drawback of this image processing method is that said virtual image does not have an appearance and colors which are really close to those of the original painting. As a result, the information that this virtual image is supposed to provide is not readily available. The object of the present invention is to propose a method of processing images representative of a pictorial work by emission of electromagnetic radiation in the direction of said work, which makes it possible to obtain at least one virtual image whose appearance and colors are close to those of said work and which gathers the information provided by the invisible rays mentioned above. To this end, the method according to the invention consists in taking at least three photographs of said work from the same angle of view and corresponding respectively to radiation of different wavelengths, which belong to the visible and invisible spectra, and to them. combine them so as to obtain at least one virtual image based on fundamental colors, the colors of said or each virtual image being respectively associated with said radiations in the same order of wavelengths.
Selon une autre caractéristique de l'invention, le procédé consiste ensuite à réaliser la différence, pour au moins chaque couleur fondamentale, de ladite image virtuelle et d'une photographie prise au moyen d'un rayonnement visible et à combiner entre elles les photographies de différence respectivement obtenues, de manière à obtenir une image virtuelle de différence à base de couleurs fondamentalesAccording to another characteristic of the invention, the method then consists in making the difference, for at least each fundamental color, of said virtual image and of a photograph taken by means of visible radiation and to combine between them the difference photographs respectively obtained, so as to obtain a virtual image of difference based on fundamental colors
Selon un second mode de réalisation de l'invention, le procédé consiste à obtenir deux images virtuelles à base de couleurs fondamentales, la première dans un premier domaine de longueurs d'onde débordant du domaine visible et la seconde dans un second domaine de longueurs d'onde incluant ledit premier domaine, de telle sorte que les rayonnements ayant servi pour l'obtention de chacune des deux images virtuelles aient en commun un rayonnement situé dans le domaine visible.According to a second embodiment of the invention, the method consists in obtaining two virtual images based on fundamental colors, the first in a first range of wavelengths extending beyond the visible range and the second in a second range of lengths d wave including said first domain, so that the radiation used to obtain each of the two virtual images have in common a radiation located in the visible domain.
Selon une variante de réalisation dudit second mode, ledit procédé consiste à obtenir une première image virtuelle à base de couleurs fondamentales, les couleurs de ladite première image étant respectivement associées à des photographies en nuances de gris prises dans le domaine visible et de part et d'autre de ce dernier, à traiter ladite première image virtuelle à base de couleurs fondamentales de manière qu'elle soit constituée de nuances de gris, et à combiner l'image virtuelle obtenue à au moins deux photographies supplémentaires dont les rayonnements respectifs débordent de part et d'autre du domaine utilisé pour l'obtention de ladite première image virtuelle, de sorte à obtenir ladite seconde image virtuelle qui soit à base de couleurs fondamentales et dont les couleurs soient respectivement associées auxdits rayonnements supplémentaires dans le même ordre de longueurs d'onde. Selon une autre caractéristique de l'invention, le procédé consiste ensuite à réaliser la différence, pour au moins chaque couleur fondamentale, de ladite seconde image virtuelle et de ladite première image virtuelle et à combiner entre elles les photographies de différence respectivement obtenues, de manière à obtenir une image virtuelle de différence à base de couleurs fondamentales. Selon une autre caractéristique de l'invention, lesdits rayonnements respectivement associés aux couleurs fondamentales rouge, vert et bleu sont constitués d'un rayonnement rouge sous fluorescence ultraviolet, d'un rayonnement visible vert et d'un rayonnement bleu sous fluorescence ultravioletAccording to an alternative embodiment of said second mode, said method consists in obtaining a first virtual image based on fundamental colors, the colors of said first image being respectively associated with photographs in shades of gray taken in the visible domain and on both sides. other of the latter, to process said first virtual image based on fundamental colors so that it consists of shades of gray, and to combine the virtual image obtained with at least two additional photographs whose respective radiations overflow and other of the domain used for obtaining said first virtual image, so as to obtain said second virtual image which is based on fundamental colors and whose colors are respectively associated with said additional radiations in the same order of lengths wave. According to another characteristic of the invention, the method then consists in making the difference, for at least each fundamental color, of said second virtual image and of said first virtual image and in combining together the difference photographs respectively obtained, so to obtain a virtual image of difference based on fundamental colors. According to another characteristic of the invention, said radiations respectively associated with the fundamental colors red, green and blue consist of red radiation under ultraviolet fluorescence, of visible green radiation and of blue radiation under ultraviolet fluorescence
Selon une autre caractéristique de l'invention, lesdits rayonnements respectivement associés aux couleurs fondamentales rouge, vert et bleu sont constitués d'un rayonnement infrarouge, d'un rayonnement vert sous fluorescence ultraviolet et d'un rayonnement visible bleuAccording to another characteristic of the invention, said radiation respectively associated with the fundamental colors red, green and blue consist of infrared radiation, of green radiation under ultraviolet fluorescence and of visible blue radiation
Selon une autre caractéristique de l'invention, lesdits rayonnements respectivement associés aux couleurs fondamentales rouge, vert et bleu sont constitues d'un rayonnement infrarouge, d'un rayonnement visible vert et d'un rayonnement ultravioletAccording to another characteristic of the invention, said radiation respectively associated with the fundamental colors red, green and blue are consisting of infrared radiation, green visible radiation and ultraviolet radiation
Selon une autre caractéristique de l'invention, lesdits rayonnements respectivement associes aux couleurs fondamentales rouge, vert et bleu sont 5 constitues d'un rayonnement infrarouge, d'un rayonnement visible vert et d'un rayonnement bleu sous fluorescence ultravioletAccording to another characteristic of the invention, said radiations respectively associated with the fundamental colors red, green and blue consist of infrared radiation, green visible radiation and blue radiation under ultraviolet fluorescence
Les caractéristiques de l'invention mentionnées ci-dessus, ainsi que d'autres, apparaîtront plus clairement a la lecture de la description suivante d'un exemple de réalisation, ladite description étant faite en relation avec les dessins joints, parmi K) lesquels la Fig 1 est un schéma simplifie du procède de traitement d'images représentatives d'une oeuvre picturale selon l'invention, et la Fig 2 est un schéma simplifié illustrant la méthode d'obtention d'une image virtuelle obtenue par le procède de traitement d'images selon l'invention 15 Le procédé de traitement d'images selon l'invention consiste essentiellement a photographier l'oeuvre picturale 10 a analyseï sous différents rayonnements électromagnétiques 20, puis a numériser et traiter les photographies obtenues correspondant auxdits rayonnements 20 de manière a obtenir au moins une image virtuelle 30, 30', 30" dont l'aspect soit proche de celui de l'oeuvre 10 observée a la () lumière réelleThe characteristics of the invention mentioned above, as well as others, will appear more clearly on reading the following description of an exemplary embodiment, said description being made in relation to the accompanying drawings, among K) which the Fig 1 is a simplified diagram of the image processing method representative of a pictorial work according to the invention, and Fig 2 is a simplified diagram illustrating the method of obtaining a virtual image obtained by the method of processing d images according to the invention The image processing method according to the invention essentially consists in photographing the pictorial work 10 to be analyzed under different electromagnetic radiation 20, then in digitizing and processing the photographs obtained corresponding to said radiation 20 so as to obtain at least one virtual image 30, 30 ', 30 "whose appearance is close to that of the work 10 observed in () real light
La première étape de photographie de l'oeuvre 10 est mise en oeuvre au moyen d'une caméra 40 permettant de prendre des vues en non et blanc dans plusieurs domaines du spectre électromagnétique situes hors du domaine visible, dont par exemple les domaines infrarouge et ultraviolet, ainsi que des vues en couleur dans le ^ domaine visible A cet effet, la caméra 40 est pourvue de filtres interferentiels 41 , 42, 43, 44 et 45, respectivement prévus pour retenir les rayonnements infrarouge (IR), rouge (R), vert (V), bleu (B) et ultraviolet (UV)The first step of photographing the work 10 is implemented by means of a camera 40 making it possible to take non-white pictures in several areas of the electromagnetic spectrum located outside the visible area, including for example the infrared and ultraviolet areas , as well as color views in the visible domain For this purpose, the camera 40 is provided with interference filters 41, 42, 43, 44 and 45, respectively designed to retain infrared (IR), red (R) radiation, green (V), blue (B) and ultraviolet (UV)
Apres avoir émis un rayonnement électromagnétique 20 en direction de l'oeuvre 10 via une source d'éclairage 50 appropriée on observe ladite oeuvie 10 au 10 moyen de la caméra 40After having emitted an electromagnetic radiation 20 in the direction of the work 10 via an appropriate light source 50, we observe the said work 10 by means of the camera 40
Lors de chaque prise de vue de l'oeuvre 10 a analyser on notera que la caméra 40 peut se trouver devant ou derrière l'oeuvre 10, suivant que l'on souhaite observer la partie réfléchie ou transmise du rayonnement incident 20 par ladite oeuvre 10 Selon un exemple de réalisation, on a saisi dix photographies de l'oeuvre 10, celle-ci étant éclairée au moyen de différents rayonnements électromagnétiques 20:During each shooting of the work 10 to be analyzed, it will be noted that the camera 40 may be in front of or behind the work 10, depending on whether one wishes to observe the reflected or transmitted part of the incident radiation 20 by said work 10 According to an exemplary embodiment, ten photographs of the work 10 were captured, the latter being lit by means of different electromagnetic radiation 20:
Photographie 1 infrarouge (longueur d'onde de 1 100 nm) Photographie 2 infrarouge (longueur d'onde de 960 nm)Photograph 1 infrared (wavelength 1100 nm) Photograph 2 infrared (wavelength 960 nm)
Photographie 3 infrarouge (longueur d'onde de 850 nm)Infrared photography 3 (850 nm wavelength)
Photographie 4 visible rougePhotograph 4 visible red
Photographie 5 visible vertPhotograph 5 visible green
Photographie 6 visible bleu Photographie 7 ultraviolet (longueur d'onde de 340 nm)Photograph 6 visible blue Photograph 7 ultraviolet (wavelength 340 nm)
Photographie 8 ultraviolet pour prise en photographie de la lumière rouge émise par fluorescencePhotograph 8 ultraviolet for taking photography of the red light emitted by fluorescence
Photographie 9 ultraviolet pour prise en photographie de la lumière verte émise par fluorescence Photographie 10 ultraviolet pour prise en photographie de la lumière bleue émise par fluorescenceUltraviolet photography 9 for photography of green light emitted by fluorescence Ultraviolet photography 9 for photography of blue light emitted by fluorescence
L'examen des photographies sélectionnées amène les observations suivantesExamination of the selected photographs leads to the following observations
On vérifie en premier lieu qu'à chaque rayonnement 20 correspond un ensemble unique de nuances de gris sur chaque photographie en noir et blanc obtenue.It is first verified that each radiation 20 corresponds to a unique set of shades of gray on each black and white photograph obtained.
Les différences de nuances de gris observées entre diverses parties de l'oeuvre 10 sur l'une de ces photographies révèlent les différences structurelles existant entre lesdites parties de l'oeuvre 10 Par exemple, on peut conclure sur la base d'une photographie réalisée sous rayonnement 20 ultraviolet que deux taches d'un tableau 10 possédant une même couleur apparente sont constituées, pour l'une, de la seule couche originelle et, pour l'autre, de deux couches peintes à deux époques différentesThe differences in shades of gray observed between various parts of the work 10 in one of these photographs reveal the structural differences existing between the said parts of the work 10 For example, we can conclude on the basis of a photograph taken under ultraviolet radiation 20 that two spots of a table 10 having the same apparent color consist, for one, of the only original layer and, for the other, of two layers painted at two different times
La seconde étape de numérisation de chaque photographie est mise en oeuvre par un ordinateur 60 équipé d'une carte d'acquisition des photographies prises par la caméra 40, laquelle est connectée audit oïdinateur 60 La troisième étape de traitement des photographies obtenues est mise en oeuvre au moyen d'un logiciel de traitement d'images dont est pourvu ledit ordinateur 60.The second step of digitizing each photograph is implemented by a computer 60 equipped with an acquisition card for the photographs taken by the camera 40, which is connected to said computer 60 The third step for processing the photographs obtained is implemented by means of image processing software provided on said computer 60.
L'étape de traitement consiste tout d'abord à caler les photographies les unes par rapport aux autres, ceci pour que la ou les images virtuelles 30, 30', 30" 97/38397 PC17FR97/00608The processing step consists first of all of wedging the photographs in relation to each other, so that the virtual image or images 30, 30 ′, 30 " 97/38397 PC17FR97 / 00608
ultérieurement obtenues soient les plus nettes possibles. Un tel calage peut par exemple être réalisé en se basant sur les craquelures de l'oeuvre 10. Ledit calage peut être suivi d'un filtrage pour améliorer encore la qualité des images, sans toutefois modifier les nuances de gris contenues dans chaque photographie. Selon un premier mode de mise en oeuvre du procédé selon l'invention, illustré à la Fig 2, l'étape de traitement consiste ensuite en une phase de combinaison d'au moins trois photographies respectivement prises sous des rayonnements 20 déterminés, de manière à obtenir une image virtuelle 30 (IM.V à la Fig 2) en couleur dont chaque point élémentaire est alors constitué par la combinaison des signaux de couleurs fondamentaux rouge, vert, bleu (RVB), ou bien cyan, magenta, jaune (CMJ) Nous nous intéresserons uniquement à la combinaison RVB dans la suite de la descriptionsubsequently obtained are as clear as possible. Such calibration can for example be carried out based on the cracks in the work 10. Said calibration can be followed by filtering to further improve the quality of the images, without however modifying the shades of gray contained in each photograph. According to a first mode of implementation of the method according to the invention, illustrated in FIG. 2, the processing step then consists of a phase of combining at least three photographs respectively taken under determined radiation, so as to obtain a virtual image 30 (IM.V in FIG. 2) in color, each elementary point of which is then constituted by the combination of the fundamental color signals red, green, blue (RGB), or else cyan, magenta, yellow (CMY) We will only focus on the RGB combination in the following description
On va passer en revue plusieurs exemples de réalisation relatifs au mode précité Exemple 1 Les photographies utilisées pour l'obtention de ladite image virtuelle 30 à base de rouge, de vert et de bleu sont respectivement les photographies 8, 5 et 10. L'image virtuelle 30 obtenue permet notamment de mettre en évidence l'ensemble des repeints de l'oeuvre 10.We will review several exemplary embodiments relating to the aforementioned mode. Example 1 The photographs used for obtaining said virtual image 30 based on red, green and blue are photographs 8, 5 and 10 respectively. The image Virtual 30 obtained in particular makes it possible to highlight all of the repaintings of work 10.
Exemple 2: Les photographies utilisées pour l'obtention de ladite image virtuelle 30 à base de rouge, de vert et de bleu sont respectivement les photographies 3, 9 et 6 L'image virtuelle 30 obtenue permet notamment de mettre en évidence les repeints anciens de l'oeuvre 10.Example 2: The photographs used to obtain said virtual image 30 based on red, green and blue are photographs 3, 9 and 6 respectively. The virtual image 30 obtained in particular makes it possible to highlight the old repaintings of work 10.
Exemple 3 Les photographies utilisées pour l'obtention de ladite image virtuelle 30 à base de rouge, de vert et de bleu sont respectivement les photographies 3, 5 et 7 L'image virtuelle 30 obtenue permet notamment d'analyser avec précision des détails de l'oeuvre 10, tels qu'une signatureEXAMPLE 3 The photographs used to obtain said virtual image 30 based on red, green and blue are photographs 3, 5 and 7 respectively. The virtual image 30 obtained in particular makes it possible to analyze details of the image with precision. work 10, such as a signature
Exemple 4 Les photographies utilisées pour l'obtention de ladite image virtuelle 30 à base de rouge, de vert et de bleu sont respectivement les photographies 3, 5 et 10 L'image virtuelle 30 obtenue permet notamment d'analyser avec précision des détails de l'oeuvre 10, tels qu'une signatureEXAMPLE 4 The photographs used to obtain said virtual image 30 based on red, green and blue are photographs 3, 5 and 10 respectively. The virtual image 30 obtained in particular makes it possible to analyze details of the image with precision. work 10, such as a signature
On vérifie que les couleurs de l'image virtuelle 30 sont voisines de celles de l'oeuvre 10 observée à la lumière réelle (image réelle IM R à la Fig. 2), du fait de la proximité existant dans l'échelle des longueurs d'onde entre, d'une part, les rayonnements 20 ultraviolet et bleu et, d'autre part, les rayonnements 20 infrarouge et rougeIt is verified that the colors of the virtual image 30 are similar to those of the work 10 observed in real light (real image IM R in Fig. 2), due to the proximity existing in the length scale d wave between, on the one hand, ultraviolet and blue radiation and, secondly, infrared and red radiation
L'image virtuelle 30 obtenue permet de réunir de nombreux renseignements relatifs aux différentes étapes constitutives de l'oeuvre. Dans le cas d'un tableau, il est ainsi possible de repérer rapidement les parties repeintes, les altérations subies par la toile, les lacunes, etc.The virtual image 30 obtained makes it possible to gather a great deal of information relating to the different stages making up the work. In the case of a painting, it is thus possible to quickly identify the repainted parts, the alterations suffered by the canvas, the gaps, etc.
De plus, il est parfois utile de disposer d'une palette de couleurs plus nuancées sur l'image virtuelle 30 A titre indicatif, le rouge est susceptible de mettre en évidence la préparation d'un tableau, l'orangé fait souvent apparaître des repeints anciens alors que le vert peut révéler des vernis anciens. Ainsi, si l'on souhaite voir apparaître une couleur telle que l'orangé dans l'image virtuelle 30, on émettra un quatrième rayonnement infrarouge de longueur d'onde voisine de 900 nmIn addition, it is sometimes useful to have a more nuanced palette of colors on the virtual image. 30 As an indication, red is likely to highlight the preparation of a painting, the orange often makes repaint appear. old while green can reveal old varnishes. Thus, if one wishes to see a color such as orange appear in the virtual image 30, a fourth infrared radiation of wavelength close to 900 nm will be emitted.
Par synthèse additive des sources colorées que constituent les pastilles de luminophores, toutes les couleurs appartenant au spectre visible peuvent être reconstituées sur l'image virtuelle 30 Ainsi, sur la base d'une source rouge et d'une source bleue, on obtiendra la couleur magenta Avec des sources rouge et verte, on obtiendra la couleur jaune, et avec des sources verte et bleue, on obtiendra la couleur cyan Par conséquent, cette méthode permet de disposer d'informations sur l'oeuvre 10 qu'il était difficile de mettre en évidence sur les différentes photographies en noir et blanc, puisque de nouvelles couleurs apparaissent sur l'image virtuelle 30By additive synthesis of the colored sources that constitute the phosphor pellets, all the colors belonging to the visible spectrum can be reconstituted on the virtual image 30 Thus, on the basis of a red source and a blue source, the color will be obtained magenta With red and green sources, we will obtain the color yellow, and with green and blue sources, we will obtain the color cyan Consequently, this method makes it possible to have information on work 10 which was difficult to put highlighted in the various black and white photographs, since new colors appear on the virtual image 30
Il est à noter qu'une large gamme de rayonnements 20 peut être utilisée dans le procédé selon l'invention, une couleur étant associée à chaque rayonnement 20 lors de la phase de combinaison des photographies respectivement prises sous des rayonnements 20 distincts L'image virtuelle 30 résultante de cette combinaison est telle que chaque point élémentaire qu'elle contient comprend les couleurs fondamentales précitées, lesquelles sont respectivement associées auxdits rayonnements 20 dans le même ordre de longueurs d'onde (λ), lesdits rayonnements 20 appartenant à un domaine plus étendu que le domaine visibleIt should be noted that a wide range of radiation 20 can be used in the method according to the invention, a color being associated with each radiation 20 during the phase of combining the photographs respectively taken under distinct radiation 20 The virtual image 30 resulting from this combination is such that each elementary point which it contains comprises the aforementioned fundamental colors, which are respectively associated with said rays 20 in the same order of wavelengths (λ), said rays 20 belonging to a more extensive domain that the visible area
L'étape de traitement consiste ensuite à réaliser la différence, pour au moins chaque couleur fondamentale, de ladite image virtuelle 30 et d'une photographie prise au moyen d'un rayonnement 20 visible et à combiner entre elles les photographies de différence respectivement obtenues, de manière à obtenir une image virtuelle de différence à base de couleurs fondamentales Ladite image virtuelle de différence permet de visualiser précisément les détails de l'image virtuelle 30 qui ne sont pas contenus dans l'image visible.The processing step then consists in making the difference, for at least each fundamental color, of said virtual image 30 and of a photograph taken by means of visible radiation 20 and in combining together the difference photographs respectively obtained, so as to obtain a virtual difference image based on fundamental colors Said virtual difference image allows to visualize precisely the details of the virtual image 30 which are not contained in the visible image.
On procède à une comparaison de l'image virtuelle 30 avec la photographie de l'oeuvre 10 réalisée en lumière visible, suivie de divers réglages et d'une correction apportée à ladite image virtuelle 30 pour faire en sorte qu'elle se rapproche encore davantage de l'image réelle. On procède par exemple à une correction gamma et à des réglages des intensités maxima RVB.A comparison is made of the virtual image 30 with the photograph of the work 10 carried out in visible light, followed by various adjustments and a correction made to said virtual image 30 in order to make it come even closer. from the actual image. For example, gamma correction and adjustments to the maximum RGB intensities are carried out.
Selon un second mode de réalisation, on réalise deux images virtuelles 30' etAccording to a second embodiment, two virtual images 30 ′ are produced and
30" à base de couleurs fondamentales conformément au protocole décrit ci-dessus. La première image virtuelle 30' englobe un premier domaine de longueurs d'onde débordant du domaine visible Quant à la seconde image virtuelle 30", elle englobe un second domaine de longueurs d'onde incluant ledit premier domaine, de telle sorte que les rayonnements 20 ayant servi pour l'obtention de chacune des deux images virtuelles 30' et 30" aient en commun un rayonnement 20 situé dans le domaine visible. Les rayonnements 20 utilisés peuvent par exemple être choisis parmi ceux qui sont à l'origine des dix photographies précitées.30 "based on fundamental colors in accordance with the protocol described above. The first virtual image 30 'encompasses a first wavelength domain extending beyond the visible domain As for the second virtual image 30", it encompasses a second length domain wave including said first domain, so that the radiation 20 used to obtain each of the two virtual images 30 ′ and 30 ″ have in common a radiation 20 located in the visible domain. The radiation 20 used can by example be chosen from those who are at the origin of the ten aforementioned photographs.
Dans ce mode de réalisation, les rayonnements 20 sélectionnés pour donner chaque image virtuelle 30' ou 30" sont, pour trois d'entre eux, respectivement associés aux couleurs rouge, vert, bleu (ou magenta, jaune, cyan) suivant l'ordre décroissant de leurs longueurs d'onde. L'organisation du spectre de la lumière visible sert donc de référence. L'image servant de base à l'analyse est celle dont le spectre est le plus étendu, c'est-à-dire ladite seconde image virtuelle 30".In this embodiment, the rays 20 selected to give each virtual image 30 ′ or 30 ″ are, for three of them, respectively associated with the colors red, green, blue (or magenta, yellow, cyan) according to the order decreasing wavelengths. The organization of the visible light spectrum therefore serves as a reference. The image used as the basis for the analysis is the one with the widest spectrum, that is to say the said second 30 "virtual image.
De même que précédemment, on réalise ensuite la différence, pour au moins chaque couleur fondamentale, de ladite seconde image virtuelle 30" et de ladite première image virtuelle 30' et on combine entre elles les photographies de différence respectivement obtenues, de manière à obtenir une image virtuelle de différence à base de couleurs fondamentales Cette dernière permet de visualiser les détails de ladite seconde image virtuelle 30" qui ne sont pas contenus dans ladite première image virtuelle 30'. De la même manière que pour le premier mode de réalisation, on compare ensuite la seconde image virtuelle 30" à la première 30', afin d'en corriger les différences par des réglages et corrections appropriés.As previously, the difference is then made, for at least each fundamental color, of said second virtual image 30 "and of said first virtual image 30 'and the difference photographs respectively obtained between them are combined, so as to obtain a virtual image of difference based on fundamental colors The latter makes it possible to view the details of said second virtual image 30 ″ which are not contained in said first virtual image 30 ′. In the same way as for the first embodiment, the second virtual image 30 "is then compared to the first 30 ', in order to correct the differences by appropriate adjustments and corrections.
Selon une variante de réalisation dudit second mode, ladite première image virtuelle 30' est obtenue de la manière suivante. En accord avec le protocole mentionné dans ledit premier mode, l'on combine une photographie prise dans le domaine visible qui est traitée de manière à être constituée de nuances de gris et au moins deux photographies prises de part et d'autre dudit domaine visible sur le spectre électromagnétique, par exemple dans les domaines infrarouge proche et ultraviolet proche On obtient ainsi la première image virtuelle 30', laquelle est à base de couleurs résultant d'une combinaison de signaux RVB.According to an alternative embodiment of said second mode, said first virtual image 30 ′ is obtained in the following manner. In accordance with the protocol mentioned in said first mode, a photograph taken in the visible range is combined which is treated so as to consist of shades of gray and at least two photographs taken on either side of said visible range on the electromagnetic spectrum, by example in the near infrared and near ultraviolet domains The first virtual image 30 ′ is thus obtained, which is based on colors resulting from a combination of RGB signals.
Quant à la seconde image virtuelle 30", elle est obtenue de la manière suivanteAs for the second 30 "virtual image, it is obtained in the following manner
On traite tout d'abord ladite première image virtuelle 30' en couleur, de telle manière à obtenir une image virtuelle qui soit constituée des nuances de gris correspondant à des combinaisons desdites couleurs R, V, B.First of all, said first virtual image 30 ′ is processed in color, so as to obtain a virtual image which is made up of shades of gray corresponding to combinations of said colors R, G, B.
Conformément au protocole dudit premier mode, on combine ensuite cette image virtuelle en noir et blanc à au moins deux photographies supplémentaires, également en noir et blanc, de manière à obtenir ladite seconde image virtuelle 30" à base de signaux RVB. Ces photographies supplémentaires sont respectivement prises sous des rayonnements satisfaisant à la condition suivante.According to the protocol of said first mode, this virtual black and white image is then combined with at least two additional photographs, also in black and white, so as to obtain said second virtual image 30 "based on RGB signals. These additional photographs are respectively taken under radiation satisfying the following condition.
Ces derniers rayonnements sont situés de part et d'autre des rayonnements extrêmes qui ont servi à l'obtention de ladite première image virtuelle 30', sur le spectre électromagnétique. Ainsi, dans l'exemple 3 précité, les rayonnements utilisés pour lesdites photographies supplémentaires seront respectivement caractérisés par une longueur d'onde supérieure à 850 nm et par une longueur d'onde inférieure à 340 nmThese latter radiations are located on either side of the extreme radiations which were used to obtain said first virtual image 30 ′, on the electromagnetic spectrum. Thus, in example 3 above, the radiation used for said additional photographs will be respectively characterized by a wavelength greater than 850 nm and by a wavelength less than 340 nm
Avantageusement, les rayonnements utilisés pour ces photographies supplémentaires appartiennent respectivement aux domaines de l'infrarouge lointain et de l'ultraviolet lointain.Advantageously, the radiation used for these additional photographs belongs respectively to the fields of far infrared and far ultraviolet.
On notera que la première image virtuelle 30' et les photographies supplémentaires prises sous rayonnements infrarouge et ultraviolet lointains qui ont été sélectionnées pour donner la seconde image virtuelle 30" sont, pour trois d'entre elles, respectivement associées aux couleurs fondamentales vert, rouge et bleu, c'est- à-dire en conservant le même ordre des longueurs d'onde pour les rayonnements visible et invisibleIt will be noted that the first virtual image 30 ′ and the additional photographs taken under far infrared and ultraviolet radiation which have been selected to give the second virtual image 30 ″ are, for three of them, respectively associated with the fundamental colors green, red and blue, i.e. keeping the same wavelength order for visible and invisible radiation
De même que précédemment, on réalise ensuite la différence, pour au moins chaque couleur fondamentale R, V, B, de cette seconde image virtuelle 30" et de ladite première image virtuelle 30', puis on combine entre elles les photographies de différence respectivement obtenues de manière a obtenir une image virtuelle de différence à base de couleurs fondamentales On corrige également les différences existant entre les images virtuelles 30' et 30" par des réglages appropriesAs before, the difference is then made, for at least each fundamental color R, G, B, of this second virtual image 30 "and of said first virtual image 30 ', then the photographs of them are combined. difference respectively obtained so as to obtain a virtual image of difference based on fundamental colors. The differences between the 30 'and 30' virtual images are also corrected by appropriate adjustments.
On notera qu'il serait également possible de procéder a la différenciation et à la comparaison de ladite seconde image virtuelle 30" et de la photographie de l'oeuvre 10 en lumière visible, de manière a obtenir une image virtuelle de différence à base de couleurs fondamentalesIt will be noted that it would also be possible to differentiate and compare said second virtual image 30 "and the photograph of work 10 in visible light, so as to obtain a virtual image of difference based on colors. fundamental
On comprendra que ce second mode de réalisation ne se limite pas a l'obtention de deux images virtuelles 30' et 30" que l'on compare entre elles ou bien a une photographie de l'oeuvre 10 en lumière visible Le procède selon ce second mode pourrait également être mis en oeuvre par l'intermédiaire de plus de deux images virtuelles Dans ce cas, l'image virtuelle en RVB de rang n (n > 2) serait obtenue par la combinaison de l'image virtuelle en RVB de rang n- 1 , traitée de manière à être formée uniquement de nuances de gris, et d'au moins deux photographies supplémentaires prises sous des rayonnements débordant du domaine qui est délimite par les photographies ayant servi à l'obtention de ladite image virtuelle de rang n- 1 (on pourrait par exemple utiliser des rayonnements X ou Gamma a la place des rayonnements ultraviolets) Dans ce cas, l'image virtuelle de rang n- 1 serait associée à la couleur fondamentale verte pour l'obtention de l'image virtuelle de rang n De même que précédemment, on pourrait réahseï la différence, pour au moins chaque couleur fondamentale, de l'image virtuelle de rang n et de l'une au choix des images virtuelles de rang inférieur a n, ou bien de la photographie de l'oeuvre 10 en lumière visibleIt will be understood that this second embodiment is not limited to obtaining two virtual images 30 ′ and 30 ″ which are compared with one another or else to a photograph of the work 10 in visible light. The method according to this second mode could also be implemented by means of more than two virtual images In this case, the virtual image in RGB of rank n (n> 2) would be obtained by the combination of the virtual image in RGB of rank n - 1, treated so as to be formed only of shades of gray, and at least two additional photographs taken under radiation extending beyond the domain which is delimited by the photographs having served to obtain said virtual image of rank n- 1 (we could for example use X or Gamma rays instead of ultraviolet rays) In this case, the virtual image of rank n- 1 would be associated with the fundamental green color for obtaining the virtual image of rank n Similarly that previously, we could re-analyze the difference, for at least each fundamental color, of the virtual image of rank n and of one of the choice of virtual images of rank lower an, or else of the photograph of the work 10 in visible light
La méthode illustrée dans le second mode de réalisation qui vient d'être décrit permet notamment de différencier les lacunes véritables des parties constitutives de l'oeuvre 10 En effet, dans le cas d'un tableau, il peut arriver que l'image virtuelle 30 obtenue conformément au premier mode de réalisation mette en évidence des zones claires, que l'on pourrait assimiler a tort a des lacunes D'où l'idée de modifier les couleurs de la photographie de référence pour la comparaison en quittant au moins partiellement le domaine visible, pour éviter une telle confusionThe method illustrated in the second embodiment which has just been described makes it possible in particular to differentiate the real shortcomings of the constituent parts of the work 10 Indeed, in the case of a painting, it may happen that the virtual image 30 obtained in accordance with the first embodiment highlights clear areas, which one could mistakenly assimilate to gaps Hence the idea of modifying the colors of the reference photograph for comparison by leaving at least partially the field visible, to avoid such confusion
Dans le cas d'un tableau cette méthode permel également d'observer précisément les degrés d'altération de la couche picturale, de la préparation et de la toile I l 97/38397 PCT/FR97/00608In the case of a painting, this method also allows to observe precisely the degrees of alteration of the pictorial layer, the preparation and the canvas. I l 97/38397 PCT / FR97 / 00608
Une première condition nécessaire à la mise en oeuvre du procédé selon l'invention est que l'oeuvre 10 soit telle qu'elle puisse donner lieu à au moins deux nuances de gris appartenant à la même matière, sur chaque photographie prise en noir et blanc Une seconde condition est que les photographies obtenues puissent être mises à la même dimension et qu'elles aient toutes été prises selon le même angle de vue.A first condition necessary for implementing the method according to the invention is that the work 10 is such that it can give rise to at least two shades of gray belonging to the same material, on each photograph taken in black and white. A second condition is that the photographs obtained can be set to the same dimension and that they have all been taken from the same angle of view.
Une troisième condition est bien entendu que la matière de l'oeuvre 10 soit sensible aux différents rayonnements utilisés du spectre électromagnétique. On notera que le procédé de traitement d'images selon l'invention a d'autant plus d'intérêt que le nombre de nuances distinctes de gris est élevé. A titre indicatif, on en dénombre jusqu'à mille pour certaines images étudiées en médecine.A third condition is of course that the material of the work 10 is sensitive to the different radiations used of the electromagnetic spectrum. It will be noted that the image processing method according to the invention is all the more advantageous the higher the number of distinct shades of gray. As an indication, there are up to a thousand for certain images studied in medicine.
Le procédé selon l'invention pourrait consister à prendre plus de trois photographies dans les domaines visible et invisible dans chacun des modes de réalisation précités, pourvu que les rayonnements 20 sous lesquels sont respectivement prises lesdites photographies soient associées aux couleurs de l'image virtuelle 30, 30', 30" dans le même ordre de longueurs d'onde. The method according to the invention could consist in taking more than three photographs in the visible and invisible fields in each of the abovementioned embodiments, provided that the rays 20 under which said photographs are taken respectively are associated with the colors of the virtual image 30 , 30 ', 30 "in the same order of wavelengths.

Claims

REVENDICATIONS
1 ) Procédé de traitement d'images représentatives d'une oeuvre picturale (10) par émission de rayonnements électromagnétiques (20) en direction de ladite oeuvre ( 10), caractérisé en ce qu'il consiste à prendre au moins trois photographies de ladite oeuvre ( 10) sous le même angle de vue et correspondant respectivement à des rayonnements (20) de longueurs d'onde différentes, lesquelles appartiennent aux spectres visible et invisible, et à les combiner entre elles de manière à obtenir au moins une image virtuelle (30, 30', 30") à base de couleurs fondamentales, les couleurs de ladite ou chaque image virtuelle (30, 30', 30") étant respectivement associées auxdits rayonnements (20) dans le même ordre de longueurs d'onde 2) Procédé de traitement d'images selon la revendication 1 , caractérisé en ce qu'il consiste ensuite à réaliser la différence, pour au moins chaque couleur fondamentale, de ladite image virtuelle (30) et d'une photographie prise au moyen d'un rayonnement (20) visible et à combiner entre elles les photographies de différence respectivement obtenues, de manière à obtenir une image virtuelle de différence à base de couleurs fondamentales.1) Process for processing images representative of a pictorial work (10) by emission of electromagnetic radiation (20) in the direction of said work (10), characterized in that it consists in taking at least three photographs of said work (10) from the same viewing angle and corresponding respectively to radiation (20) of different wavelengths, which belong to the visible and invisible spectra, and to combine them so as to obtain at least one virtual image (30 , 30 ', 30 ") based on fundamental colors, the colors of said or each virtual image (30, 30', 30") being respectively associated with said radiations (20) in the same order of wavelengths 2) Method image processing device according to claim 1, characterized in that it then consists in making the difference, for at least each fundamental color, of said virtual image (30) and of a photograph taken by means of a ra visible (20) and to combine the difference photographs obtained respectively, so as to obtain a virtual difference image based on fundamental colors.
3) Procédé de traitement d'images selon la revendication 1 , caractérisé en ce qu'il consiste à obtenir deux images virtuelles (30' et 30") à base de couleurs fondamentales, la première (30') dans un premier domaine de longueurs d'onde débordant du domaine visible et la seconde (30") dans un second domaine de longueurs d'onde incluant ledit premier domaine, de telle sorte que les rayonnements (20) ayant servi pour l'obtention de chacune des deux images virtuelles (30', 30") aient en commun un rayonnement (20) situé dans le domaine visible.3) Image processing method according to claim 1, characterized in that it consists in obtaining two virtual images (30 'and 30 ") based on fundamental colors, the first (30') in a first range of lengths wave extending beyond the visible range and the second (30 ") in a second range of wavelengths including said first range, so that the radiation (20) used to obtain each of the two virtual images ( 30 ', 30 ") have in common a radiation (20) located in the visible range.
4) Procédé de traitement d'image selon la revendication 1 , caractérisé en ce qu'il consiste à obtenir une première image virtuelle (30') à base de couleurs fondamentales, les couleurs de ladite première image (30') étant respectivement associées a des photographies en nuances de gris prises dans le domaine visible et de part et d'autre de ce dernier, à traiter ladite première image virtuelle (30') à base de couleurs fondamentales de manière qu'elle soit constituée de nuances de gris, et à combiner l'image virtuelle obtenue à au moins deux photographies supplémentaires dont les rayonnements (20) respectifs débordent de part et d'autre du domaine utilisé pour l'obtention de ladite première image virtuelle (30'), de sorte à obtenir ladite seconde image virtuelle (30") qui soit à base de couleurs fondamentales et dont les couleurs soient respectivement associées auxdits rayonnements supplémentaires (20) dans le même ordre de longueurs d'onde.4) Image processing method according to claim 1, characterized in that it consists in obtaining a first virtual image (30 ') based on fundamental colors, the colors of said first image (30') being respectively associated with photographs in shades of gray taken in the visible area and on either side of the latter, to process said first virtual image (30 ′) based on fundamental colors so that it is made up of shades of gray, and combining the virtual image obtained with at least two additional photographs, the respective rays (20) of which extend beyond either side of the area used to obtain said first virtual image (30 '), so as to obtain said second virtual image (30 ") which is based on fundamental colors and whose colors are respectively associated with said additional radiation (20) in the same order of wavelengths.
5) Procédé de traitement d'images selon la revendication 3 ou 4, caractérisé en ce qu'il consiste ensuite à réaliser la différence, pour au moins chaque couleur fondamentale, de ladite seconde image virtuelle (30") et de ladite première image virtuelle (30') et à combiner entre elles les photographies de différence respectivement obtenues, de manière à obtenir une image virtuelle de différence à base de couleurs fondamentales5) image processing method according to claim 3 or 4, characterized in that it then consists in making the difference, for at least each fundamental color, of said second virtual image (30 ") and said first virtual image (30 ') and to combine the difference photographs obtained respectively, so as to obtain a virtual difference image based on fundamental colors
6) Procédé de traitement d'images selon l'une des revendications précédentes, caractérisé en ce que lesdits rayonnements (20) respectivement associés aux couleurs fondamentales rouge, vert et bleu sont constitués d'un rayonnement rouge sous fluorescence ultraviolet, d'un rayonnement visible vert et d'un rayonnement bleu sous fluorescence ultraviolet6) image processing method according to one of the preceding claims, characterized in that said radiation (20) respectively associated with the fundamental colors red, green and blue consist of red radiation under ultraviolet fluorescence, of radiation visible green and blue radiation under ultraviolet fluorescence
7) Procédé de traitement d'images selon l'une des revendications 1 à 5, caractérisé en ce que lesdits rayonnements (20) respectivement associés aux couleurs fondamentales rouge, vert et bleu sont constitués d'un rayonnement infrarouge, d'un rayonnement vert sous fluorescence ultraviolet et d'un rayonnement visible bleu7) image processing method according to one of claims 1 to 5, characterized in that said radiation (20) respectively associated with the basic colors red, green and blue consist of infrared radiation, green radiation under ultraviolet fluorescence and blue visible radiation
8) Procédé de traitement d'images selon l'une des revendications 1 à 5, caractérisé en ce que lesdits rayonnements (20) respectivement associés aux couleurs fondamentales rouge, vert et bleu sont constitués d'un rayonnement infrarouge, d'un rayonnement visible vert et d'un rayonnement ultraviolet8) image processing method according to one of claims 1 to 5, characterized in that said radiation (20) respectively associated with the basic colors red, green and blue consist of infrared radiation, visible radiation green and ultraviolet
9) Procédé de traitement d'images selon l'une des revendications 1 à 5, caractérisé en ce que lesdits rayonnements (20) respectivement associés aux couleurs fondamentales rouge, vert et bleu sont constitués d'un rayonnement infrarouge, d'un rayonnement visible vert et d'un rayonnement bleu sous fluorescence ultraviolet 9) image processing method according to one of claims 1 to 5, characterized in that said radiation (20) respectively associated with the basic colors red, green and blue consist of infrared radiation, visible radiation green and blue radiation under ultraviolet fluorescence
PCT/FR1997/000608 1996-04-05 1997-04-04 Method for processing images representing a painting WO1997038397A1 (en)

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FR9604545A FR2747213B1 (en) 1996-04-05 1996-04-05 PROCESS FOR PROCESSING IMAGES REPRESENTATIVE OF A PICTURAL WORK
FR96/04545 1996-04-05

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US7042567B2 (en) * 2000-12-08 2006-05-09 Foundation Of Research And Technology Imaging method and apparatus for the non-destructive analysis of paintings and monuments
ITMI20021361A1 (en) * 2002-06-20 2003-12-22 Milano Politecnico ANALYSIS OF ARTWORKS BY USING THE FLUORESCENCE SPECTROSCOPY FOR IMAGES
FR3031182B1 (en) * 2014-12-24 2017-01-06 Univ Bordeaux Montaigne LED SPECTROFLUORIMETER FOR THE ANALYSIS OF AN OBJECT

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4170987A (en) * 1977-11-28 1979-10-16 California Institute Of Technology Medical diagnosis system and method with multispectral imaging
WO1992001920A1 (en) * 1990-07-20 1992-02-06 Joseph Piron Method and device for exploring art works and, particularly, leonardo de vinci paintings

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4170987A (en) * 1977-11-28 1979-10-16 California Institute Of Technology Medical diagnosis system and method with multispectral imaging
WO1992001920A1 (en) * 1990-07-20 1992-02-06 Joseph Piron Method and device for exploring art works and, particularly, leonardo de vinci paintings

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
FREIFELD K: "ART ANALYSIS: PROBING BENEATH THE IMAGE", IEEE SPECTRUM, 1 June 1986 (1986-06-01), pages 66 - 71, XP000606067 *
HEITZ F ET AL: "EVENT DETECTION IN MULTISOURCE IMAGING: APPLICATION TO FINE ARTS PAINTING ANALYSIS", IEEE TRANSACTIONS ON ACOUSTICS,SPEECH AND SIGNAL PROCESSING, vol. 38, no. 4, 1 April 1990 (1990-04-01), pages 695 - 704, XP000128139 *
WAXMAN A M ET AL: "COLOR NIGHT VISION: FUSION OF INTENSIFIED VISIBLE AND THERMAL IR IMAGERY", PROCEEDINGS OF THE SPIE, vol. 2463, 1 January 1995 (1995-01-01), pages 58 - 68, XP000565343 *

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