CN102332238A - Method for generating target gamma curve of display based on visual discrimination requirement - Google Patents

Abstract

The invention discloses a method for generating a target gamma curve of a display based on a visual discrimination requirement. A just-noticeable difference (JND) is subjected to segment and distributed calculation according to a calculation formula and an inverse operation formula of an index relationship between brightness and the JND by combining the native gamma curve of the display on the basis of a display requirement, a JND index value is calculated, the target gamma curve is finally obtained, and all or part of gray scales of the generated target gamma curve can completely accord with equal-difference discrimination of human vision on the basis of the display requirement after the generated target gamma curve passes the verification of the display. The method is simple and effective, can be suitable for effectively generating the target gamma curves of various displays and is also suitable for other application of the curve, and data is simply and conveniently calculated and accurately and reliably corrected.

Description

Generation method based on the display target gamma curve of visual discrimination demand

Technical field

The present invention relates to a kind of generation method, belong to the display application field based on the target gamma curve in the display correction process of visual discrimination demand.

Background technology

Display requirement to display technique in different industries is used is also different; If the data that display is directly come in input without conversion show; Its display effect often can not meet the visual discrimination requirement that shows that application is required fully, and many effective detail of information can't be perceiveed by human eye; And the different application field is also different to the requirement of display effect, and therefore, the especially professional display of display need carry out gamma curve correcting according to different application, just can reach satisfied display effect.

On display; The GTG of different brackets or luminosity response trend that color range constituted from low to high; It is exactly gamma curve; Common GTG, the color range figure place that can show according to the display capabilities of display measured each exponent number certificate with color analysis instrument, these discrete datas coupled together just constitute gamma curve.Wherein, display effect gamma curve pairing, that can react the use needs is exactly the target gamma curve, and measuring without the resulting gamma curve of the display of overcorrect is this machine gamma curve of display.In the past in the target gamma curve fitting technique, GSDF function, polynomial equation, segmentation gamma curve of γ power function, DICOM etc. are arranged, its fit procedure is each has something to recommend him, but does not carry out match from the visual discrimination angle.Design a kind of computing method, this machine gamma curve can better be overlapped with the target gamma curve,, just become the problem that the present invention will solve to satisfy the actual needs of using according to visual discrimination.

Summary of the invention

The purpose of this invention is to provide a kind of effective generation method based on visual discrimination demand display target gamma curve; Utilize this method can this machine of display gamma curve effectively be proofreaied and correct to the target gamma curve; Thereby guarantee that display has the display effect that satisfies the visual discrimination demand; Guarantee display quality, satisfy actual use needs.

The present invention realizes through following steps:

A kind of generation method of the display target gamma curve based on the visual discrimination demand comprises, at first, measures this machine gamma curve of display, and wherein black burst brightness is designated as Lmin, and white field signal brightness is designated as Lmax; The exponent number of confirming gamma curve is I, and i is the rank number of gamma curve; Application according to display is carried out segmentation with the differential distribution of JND, and by the normalization requirement, the two ends JND that sets each section JND distribution is differential; With the differential substitution function of the two ends JND analytic expression J ' that sets (i)=a * i+b, calculate parameter a and b; Again with the parameter a that calculates and b substitution function analytic expression J ' (i)=a * i+b, the JND that calculates each rank is differential; Use black field brightness Lmin and white brightness Lmax, according to the inverse operation computing formula of brightness and JND index relative:

j(L)＝A+B·Log ₁₀(L)+C·(Log ₁₀(L)) ²+D·(Log ₁₀(L)) ³+E·(Log ₁₀(L)) ⁴+

F·(Log ₁₀(L)) ⁵+G·(Log ₁₀(L)) ⁶+H·(Log ₁₀(L)) ⁷+I·(Log ₁₀(L)) ⁸

Wherein: j is the JND index value, and L is brightness, coefficient A=71.498068, B=94.593053, C=41.912053, D=9.8247004, E=0.28175407, F=-1.1878455, G=-0.18014349, H=0.14710899, I=-0.017046845; Calculate the JND index value j (Lmin) of black field brightness Lmin and the JND index value j (Lmax) of white brightness Lmax respectively.

Then, calculate the enlargement factor m of the differential numerical value of normalization JND, the computing formula of m is:

m＝(j(Lmax)-j(Lmin))/∑J’(i)

Wherein ∑ J ' is the differential sum of normalization JND on each rank (i), and the scope of i is 0～I;

Calculate the differential J of JND (i) on each rank, computing formula is:

J(i)＝m×J’(i)

Then, calculate the JND index value on each rank, computing formula is:

j(Lk)＝∑J(i)+j(Lmin)

Wherein, Lk is the corresponding brightness in these rank, and j (Lmin) is the JND index value of brightness Lmin, and k is the GTG order, and ∑ J (i) is the differential sum of JND, and the span of i is 0～k.

At last, the computing computing formula according to brightness and JND index relative is:

${\log }_{10}L\left(j\right)=\frac{a+c\·\mathrm{Ln}\left(j\right)+e\·{\left(\mathrm{Ln}\left(j\right)\right)}^2+g\·{\left(\mathrm{Ln}\left(j\right)\right)}^3+m\·{\left(\mathrm{Ln}\left(j\right)\right)}^4}{1+b\·\mathrm{Ln}\left(j\right)+d\·{\left(\mathrm{Ln}\left(j\right)\right)}^2+f\·{\left(\mathrm{Ln}\left(j\right)\right)}^3+h\·{\left(\mathrm{Ln}\left(j\right)\right)}^4+k\·{\left(\mathrm{Ln}\left(j\right)\right)}^5}$

Wherein: L is brightness, and j is the JND index value, and Ln is a natural logarithm, coefficient a=-1.3011877; B=-2.5840191E-2, c=8.0242636E-2, d=-1.0320229E-1; E=1.3646699E-1, f=2.8745620E-2, g=-2.5468404E-2; H=-3.1978977E-3, k=1.2992634E-4, m=1.3635334E-3; Calculate the data of target gamma curve, and, verify through display according to this machine gamma curve data and target gamma curve data computation table of corrections.

Said application according to display is divided into 1～(I-1) section with the differential distribution of JND according to the application of display.

Said exponent number I is 256 or 1024.

The generation method of the display target gamma curve based on the visual discrimination demand of the present invention; According to DICOM the 14th partial linear JND (Just-Noticeable Difference; It is poor just to have distinguished) thought that distributes of index; For carrying out the mode that segmentation distributes, make the target gamma curve that generates in the trimming process can accurately satisfy the visual discrimination of display application JND index changes in distribution according to the visual discrimination demand.Its data computation process is simple, convenient, and calibration accuracy, effective is applicable to effective generation of various display target gamma curve, also is applicable to other application of this curve.

Description of drawings

Fig. 1 is the operational flowchart of target gamma curve generation method according to the invention;

Fig. 2 is the differential figure of JND that meets DICOM GSDF curve;

Fig. 3 is the DICOM GSDF curve map of corresponding diagram 2;

Fig. 4 is the differential figure of a kind of JND of serpentine curve;

Fig. 5 is the serpentine curve map of corresponding diagram 4.

Embodiment

1 couple of the present invention does further description below in conjunction with accompanying drawing:

The generation method of the display target gamma curve based on the visual discrimination demand of the present invention comprises:

Step 11 is measured this machine gamma curve of display, and wherein, black burst brightness is designated as Lmin, and white field signal brightness is designated as Lmax.

Step 12 is confirmed the exponent number I of gamma curve, and I is 256, and i is the rank number of gamma curve, i=0,1,2,3......255.Certainly, get differently according to display, I also can be 1024.

Step 13 is carried out segmentation according to the application of display with the differential distribution of JND.As: with 3 sections be example, dark space (0～10 rank), middle GTG district (11～128 rank), clear zone (129～255 rank).The hop count and the rank district that certainly, also can be divided into other according to actual conditions.

Step 14 is differential by normalization calculating with JND temporarily, and promptly JND is differential between 0～1.It is differential to set the two ends JND that each section JND distributes, and for example: dark space starting point JND is differential to be 0, terminal point is 1; Middle GTG district JND is differential all to be 1, clear zone starting point JND is differential to be 1, terminal point JND differential differential through the JND that sets 256 virtual rank be 0 to realize.With linear function analytic expression J ' (i)=a * i+b calculates the parameter in the analytic expression respectively, draws the dark space: a=1/10, b=0; Middle GTG district: a=0, b=1; Clear zone: a=-1/127, b=256/127; Respectively operation parameter a and b substitution function analytic expression J ' (i)=a * i+b in, the differential j ' of JND that calculates each rank is (i).

Certainly, the analytic expression in the above-mentioned steps 14 also can be set at other linear function analytic expression, at this, does not do any type of restriction.

Step 15 is used black field brightness Lmin and white brightness Lmax, according to the inverse operation computing formula of brightness and JND index relative:

j(L)＝A+B·Log ₁₀(L)+C·(Log ₁₀(L)) ²+D·(Log ₁₀(L)) ³+E·(Log ₁₀(L)) ⁴+

F·(Log ₁₀(L)) ⁵+G·(Log ₁₀(L)) ⁶+H·(Log ₁₀(L)) ⁷+I·(Log ₁₀(L)) ⁸

Calculate the JND index value j (Lmin) of black field brightness Lmin and the JND index value j (Lmax) of white brightness Lmax respectively.Wherein, j is the JND index value, and L is brightness, coefficient A=71.498068, B=94.593053, C=41.912053, D=9.8247004, E=0.28175407, F=-1.1878455, G=-0.18014349, H=0.14710899, I=-0.017046845.

Step 16 is used formula m=(j (Lmax)-j (Lmin))/∑ J ' (i), calculates the enlargement factor m of the differential normalization numerical value of JND; Then, use formula J (i)=m * J ' (i), calculate the differential J of JND (i) on each rank; Re-use formula j (Lk)=∑ J (i)+j (Lmin), calculate the JND index value on each rank.

Step 17 is according to the computing computing formula of brightness and JND index relative:

${\log }_{10}L\left(j\right)=\frac{a+c\·\mathrm{Ln}\left(j\right)+e\·{\left(\mathrm{Ln}\left(j\right)\right)}^2+g\·{\left(\mathrm{Ln}\left(j\right)\right)}^3+m\·{\left(\mathrm{Ln}\left(j\right)\right)}^4}{1+b\·\mathrm{Ln}\left(j\right)+d\·{\left(\mathrm{Ln}\left(j\right)\right)}^2+f\·{\left(\mathrm{Ln}\left(j\right)\right)}^3+h\·{\left(\mathrm{Ln}\left(j\right)\right)}^4+k\·{\left(\mathrm{Ln}\left(j\right)\right)}^5}$

Calculate the data of target gamma curve, each rank brightness data is followed successively by Lmin, L1, L2, L3......Lmax totally 1 data.Wherein, L is brightness, and j is the JND index value, and Ln is a natural logarithm; Coefficient a=-1.3011877, b=-2.5840191E-2, c=8.0242636E-2, d=-1.0320229E-1; E=1.3646699E-1, f=2.8745620E-2, g=-2.5468404E-2; H=-3.1978977E-3, k=1.2992634E-4, m=1.3635334E-3.

Step 18 is verified through display according to this machine gamma curve data and target gamma curve data computation table of corrections, is obtained required display effect.

Step 19 is passed judgment on display effect through measuring, as shows normally, the completion trimming process; If not too suitable, then suitably adjust parameter, repeat above-mentioned steps 13～18 and can proofread and correct again.

Embodiment one

As shown in Figures 2 and 3; Calculate with Lmin=0.2nits and Lmax=200nits; According to above-mentioned formula JND differential dividing equally; Can draw GSDF (the Grayscale Standard Display Function GTG standard explicit function) curve of DICOM (Digital Imaging and Communications in Medicine medical treatment digitized video with communicate by letter) the 14th part, this curve is a special case of the present invention.

Embodiment two

Like Fig. 4 and shown in Figure 5, calculate with Lmin=0.2nits and Lmax=200nits, JND is distributed differentially is divided into 3 sections, and the dark space is 0～10 rank, 11～128 rank, middle GTG position, the clear zone is 129～255 rank.The dark space differential starting point of normalized JND is 0, terminal point is 1; The JND of middle grey scale normalization is differential all to be 1; The normalized starting point JND in clear zone is differential to be 1, and the differential of virtual termination 256 rank is 0.According to above-mentioned formula, thereby calculated the serpentine curve.

Claims (3)

1. the generation method based on the display target gamma curve of visual discrimination demand is characterized in that, comprise,

A) this machine gamma curve of measurement display, wherein black burst brightness is designated as Lmin, and white field signal brightness is designated as Lmax;

B) exponent number of confirming gamma curve is I, and i is the rank number of gamma curve;

C) according to the application of display segmentation is carried out in the differential distribution of JND, and by the normalization requirement, the two ends JND that sets each section JND distribution is differential;

D) with the differential substitution function of the two ends JND analytic expression J ' that sets (i)=a * i+b, calculate parameter a and b;

E) with the parameter a that calculates and b substitution function analytic expression J ' (i)=a * i+b, the JND that calculates each rank is differential;

F) use black field brightness Lmin and white brightness Lmax, according to the inverse operation computing formula of brightness and JND index relative:

j(L)＝A+B·Log ₁₀(L)+C·(Log ₁₀(L)) ²+D·(Log ₁₀(L)) ³+E·(Log ₁₀(L)) ⁴+

F·(Log ₁₀(L)) ⁵+G·(Log ₁₀(L)) ⁶+H·(Log ₁₀(L)) ⁷+I·(Log ₁₀(L)) ⁸

Wherein: j is the JND index value, and L is brightness, coefficient A=71.498068, B=94.593053, C=41.912053, D=9.8247004, E=0.28175407, F=-1.1878455, G=-0.18014349, H=0.14710899, I=-0.017046845;

Calculate the JND index value j (Lmin) of black field brightness Lmin and the JND index value j (Lmax) of white brightness Lmax respectively;

G) the enlargement factor m of the differential numerical value of calculating normalization JND, the computing formula of m is:

m＝(j(Lmax)-j(Lmin))/∑J’(i)

Wherein ∑ J ' is the differential sum of normalization JND on each rank (i), and the scope of i is 0～I;

H) calculate the differential J of JND (i) on each rank, its computing formula is:

J(i)＝m×J’(i)

I) calculate the JND index value on each rank, its computing formula is:

j(Lk)＝∑J(i)+j(Lmin)

Wherein, Lk is the corresponding brightness in these rank, and j (Lmin) is the JND index value of brightness Lmin, and k is the GTG order, and ∑ J (i) is the differential sum of JND, and the span of i is 0～k;

J) the computing computing formula according to brightness and JND index relative is:

${\log }_{10}L\left(j\right)=\frac{a+c\·\mathrm{Ln}\left(j\right)+e\·{\left(\mathrm{Ln}\left(j\right)\right)}^2+g\·{\left(\mathrm{Ln}\left(j\right)\right)}^3+m\·{\left(\mathrm{Ln}\left(j\right)\right)}^4}{1+b\·\mathrm{Ln}\left(j\right)+d\·{\left(\mathrm{Ln}\left(j\right)\right)}^2+f\·{\left(\mathrm{Ln}\left(j\right)\right)}^3+h\·{\left(\mathrm{Ln}\left(j\right)\right)}^4+k\·{\left(\mathrm{Ln}\left(j\right)\right)}^5}$

Wherein: L is brightness, and j is the JND index value, and Ln is a natural logarithm, coefficient a=-1.3011877; B=-2.5840191E-2, c=8.0242636E-2, d=-1.0320229E-1; E=1.3646699E-1, f=2.8745620E-2, g=-2.5468404E-2; H=-3.1978977E-3, k=1.2992634E-4, m=1.3635334E-3;

Calculate the data of target gamma curve;

K) according to this machine gamma curve data and target gamma curve data computation table of corrections, verify through display.

2. the generation method of the display target gamma curve based on the visual discrimination demand according to claim 1 is characterized in that, among the said step C, the differential distribution of JND is divided into 1～(I-1) section according to the application of display.

3. the generation method of the display target gamma curve based on the visual discrimination demand according to claim 1 and 2 is characterized in that said exponent number I is 256 or 1024.

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