CN104166956A - Method for embedding and extracting vector graph copyright characters - Google Patents
Method for embedding and extracting vector graph copyright characters Download PDFInfo
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- CN104166956A CN104166956A CN201410258892.5A CN201410258892A CN104166956A CN 104166956 A CN104166956 A CN 104166956A CN 201410258892 A CN201410258892 A CN 201410258892A CN 104166956 A CN104166956 A CN 104166956A
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Abstract
The invention relates to a method for embedding and extracting vector graph copyright characters. A copyright character embedding method at present is difficult to resist geometrical attacks of translation, rotation, scaling and combination thereof, and is more difficult to resist interference attacks aimed at primitive addition, modification, deletion and combination thereof. The method for embedding and extracting the vector graph copyright characters perform complex proportioning on a vector graph according to a handle value, copyright characters are embedded in the complex proportion, resistance of the copyright characters to geometrical attacks is guaranteed, a plurality of groups of copyright characters are embedded in the vector graph, so that the method in the invention has robustness for interference attacks.
Description
Technical field
The present invention relates to the encrypted copyright resist technology of vector graphics, relate in particular to a kind of embedding and extracting method of vector graphics copyright character.The inventive method can be embedded in sightless mode the copyright character that represents copyright information in vector graphics file, and can extract in a particular manner copyright character, to prove the owner of figure copyright.
Background technology
Vector graphics refers to that the geometric graphic element based on mathematical expression represents computer graphical such as point, line, curve, polygon etc. in utilization.Be different from bitmap, because vector graphics is described with mathematical feature, after its convergent-divergent, there will not be the mosaic feature of bit map type.Vector graphics is because its distortionless zoom feature and accuracy are widely used in the fields such as building, machinery, weaving, electric, building, artistic creation.Its needs that extensively use just, vector graphics is as crystallization of wisdom, creator's painstaking effort, the embodiment of everyone assets especially, the protection problem of its copyright receives much concern always.
The mode of password or digital certificate, due to its not convenient property having, is difficult to extensive popularization.In recent years, be subject to multimedia file to embed the impact of invisible copyright information technology, take the mode that embeds invisible copyright character to protect the technology of vector graphics just very more and more to receive people's concern.On the one hand, the copyright character of embedding is invisible, and the recipient of file or diffusion person are difficult for discovering; On the other hand; the definitive document that the owner sends to recipient is also unnecessary does extra encryption, and reading figure does not need through decryption step, the disguise of bringing due to this copyright protection technology and the convenience of reading; make the owner and recipient all acceptant, more and more welcome.
But the present situation of copyright character embedded technology allows of no optimist, can " be smeared " very easily, be difficult to play the effect of evidence copyright.Existing vector graphics copyright copyright character embedded technology, according to the difference of copyright character embedding grammar working field, can be divided into transform domain method and Space domain.
In transform domain, mainly realize by the technology such as wavelet transformation, Fourier transform, this conversion can be resisted the geometric operation such as overall convergent-divergent, translation and rotation, but the attack that can not resist increase, delete and revise.For example, documents 1[health is lush etc. the blind watermarking algorithm based on fractional fourier transform in two-dimensional engineering graphic. and computer utility .2009 (6)] a kind of watermarking algorithm based on fractional fourier transform proposed, the method is extracted the relative coordinate vector of vector graphics middle conductor, structuring one-dimensional complex signal, obtain the conversion coefficient of complex signal by fractional fourier transform, amplitude adjustment to conversion coefficient is carried out embed watermark, but cannot resist the interference attack such as interpolation, deletion, amendment.
In spatial domain, the attributes such as main apex coordinate, radius and angle by means of pel embed copyright character, according to the pel relying on, mainly be divided into two classes: the first kind, extract the straight line (general containing more straight line in engineering drawing) in engineering drawing, the apex coordinate of amendment straight line or straight line is transformed to multi-section-line and realizes the embedding of copyright character, but the method can not be resisted the attack of convergent-divergent, more cannot resist the attacks such as increase, deletion or amendment; Equations of The Second Kind, extract all summits of entity in engineering drawing, embed copyright character fragment by means of the amendment of summit spacing ratio, but cannot resist the attack that increases and delete pel entity, or carry out polar coordinate transform and obtain amplitude and phase place opposing Rotation and Zoom and attack, but can not resist the combination attacks of multiple geometric transformation.For example, documents 2 [Wang Yashun etc. the digital watermarking proportional algorithm based on two-dimensional engineering graphic. University Of Nanchang's journal (industry science version) .2003 (4)] a kind of algorithm that carrys out embed watermark by the ratio of each entity summit spacing in amendment engineering drawing proposed, but in the time increasing or delete pel entity, but watermark sequence accurately cannot be extracted, copyright owner can not be proved.
As above-mentioned, current vector graphics copyright character embedded technology is difficult to the geometric attack of opposing to the translation for whole figure, rotation, convergent-divergent, and being more difficult to opposing increases or delete the interference attack of pel.Tracing it to its cause, is mainly that these characteristics comprise because the inherent characteristic of vector graphics determines:
(1) the shared byte number of vector graphics file is few;
(2) the metastable transform domain of neither one can be for embedding copyright character;
(3) be easy to carry out geometric operation and cause losing copyright character fragment;
Therefore, embed copyright character more much more difficult than embed copyright character in the file such as such as bitmap, video, audio frequency, grid in vector graphics, especially characteristic (3) has been aggravated difficulty that the opposing of copyright character attacks.
In view of this, the present invention proposes a kind of embedding and extracting method of vector graphics copyright copyright character, to make up the deficiencies in the prior art.
Summary of the invention
First object of the present invention is: a kind of embedding grammar of vector graphics copyright character is provided, and the method can be resisted geometric attack, and interference attack is had to robustness.
Second object of the present invention is: a kind of extracting method of vector graphics copyright character is provided, and the method can extract copyright character from suffer the vector graphics file of interference attack.
In order to reach above-mentioned purpose, technical scheme of the present invention is as follows:
Embedding and the extracting method of vector graphics copyright character, comprise embedding step and extraction step, embeds step and comprise:
Step 1.1, structure copyright character string, the character object that represents copyright information is divided into continuous fragment, be called " character fragment ", the number of character fragment is the length of character string, wish embeds the pel number comprising in vector graphics is the length of this vector graphics, the length that is shorter in length than vector graphics of character fragment;
Step 1.2, the pel comprising for vector graphics builds complex vector operator;
Step 1.3, according to the right complex vector operator of the more adjacent order pel of the generation order of pel (handle value), obtains pel to plural ratio, and this step comparative result is called " front plural ratio ";
Step 1.4, by the part in the front plural ratio of character fragment replacement step 1.3, obtains the new plural ratio that embeds character fragment, is called " middle plural ratio ";
Step 1.5, the middle plural ratio amendment pel pair obtaining according to step 1.4, after amendment, the right plural ratio of this pel is called " rear plural ratio ", and amendment result should make rear plural ratio equal middle plural ratio.
Step 1.6, to step 1.5, is embedded into character fragment the pel centering traversing according to generation order (handle value) traversal step 1.1 of pel one by one;
Extraction step comprises the following steps:
Step 2.1, the pel comprising for vector graphics builds complex vector operator;
Step 2.2, according to the complex vector operator of the more adjacent order pel of the generation order of pel (handle value), obtains pel to plural ratio, is called " extracting plural ratio ", reading character fragment from extract plural ratio;
Step 2.3, to generating order (handle value) traversal step 2.1 to step 2.2, obtains the sample of character fragment composition according to pel;
Step 2.4, analyzing samples, determines correct character fragment and error character fragment;
Step 2.5, is reduced into character by correct character fragment.
For embedding step, preferably, the length of vector graphics and the length ratio of character string are more than or equal to 2.
For embedding step, preferably, front plural ratio and middle plural ratio and rear plural ratio are stored as double-precision floating points.
For embedding step, preferably, copyright character or character fragment did the encryption process before embedding.
For embedding step, preferably, the privileged site before copyright character replacement in plural ratio.
For embed step, preferably, amendment pel to time, only revise pel centering order pel formerly.
For embed step, preferably, amendment pel to time, only revise the posterior pel of pel centering order.
For extraction step, preferably, the traversal direction of extraction is contrary with the traversal direction of embedding.
For extraction step, preferably, the frequency that in analyzing samples, each character fragment occurs, with threshold filtering error character fragment, retains correct characters fragment.
For extraction step, preferably, sample and correct character fragment are compared, using character fragment consistent comparative result as correct characters fragment.
The present invention is embedded into character fragment in the right plural ratio of pel, instead of be directly embedded in the data structure of pel, by the right plural ratio of amendment pel, make amended pel equal rear plural ratio to plural ratio, realize the embedding of copyright character fragment.Because pel is the ratio between vector operator to plural ratio, do not change with the geometric transformation of convergent-divergent, translation, rotation or its combination; Guarantee that the present invention has the beneficial effect that can resist geometric attack.
The present invention utilizes generation order (handle value) foundation of step as a comparison of pel, is the basis with the interference attack of opposing amendment, interpolation, deletion and so on.In the process of creation vector graphics, the handle value that Authoring program distributes according to the time sequencing of pel creation has uniqueness and non-alterability, the traversal reference that utilizes the generation order of handle value to add and extract as character fragment, can ensure the directivity traveling through.Occur when interference attack, destruction be the right succession of pel in the certain limit of noise spot present position, do not affect the right order of other pel, make the present invention possess the beneficial effect of certain opposing interference attack.
As mentioned above, adopt after technical scheme of the present invention, the character fragment that is added to vector graphics can be resisted geometric attack completely; Interference attack is had to robustness.The present invention is further elaborated in the mode of embodiment below in conjunction with accompanying drawing.
Brief description of the drawings
Fig. 1 is that vector figure data is deposited and organized structure schematic diagram;
Fig. 2 is that line segment type pel builds complex vector operator schematic diagram;
Fig. 3 is that multistage line style pel builds complex vector operator schematic diagram;
Fig. 4 is that SPL type pel builds complex vector operator schematic diagram;
Fig. 5 is that circular arc type pel builds complex vector operator schematic diagram;
Fig. 6 is that character fragment is embedded into the schematic diagram in double-precision floating point data structure;
Fig. 7 is amendment SPL pel schematic diagram;
Fig. 8 is amendment arc pel schematic diagram;
Fig. 9 is that embodiment mono-intends with contrast schematic diagram before and after vector graphics amendment;
Figure 10 is that embodiment bis-intends with contrast schematic diagram before and after vector graphics amendment.
Embodiment
Because the length of byte may be different with hardware condition because of the job platform of computing machine, its length can adjust according to concrete situation, below relate to for example data length statement can not be used for limiting the present invention's spirit.
As aforementioned, vector graphics refers to that the geometric graphic element based on mathematical expression represents computer graphical such as point, line, curve, polygon etc. in utilization.Its concrete data organizational structure is different because of different plotter programs, but does not depart from the organizational factors shown in Fig. 1.The institutional framework of Fig. 1 signal is that common store structure taking dwg form is as prototype, select the example of this prototype as elaboration below, can not be with dwg format restriction the present invention's spirit, the embodiment of other vector graphics format outside dwg form, can realize with reference to the present embodiment.
Embodiment mono-
One, embed
Step 1.1
In the present embodiment, the vector graphics that wish embeds copyright character comprises
individual pel, its length is
.Represent copyright owner with character string " #xmhd ".In order to prevent that character string from illegally being identified, character string " #xmhd " is done the encryption process, preferred existing cryptographic algorithm, using character string " #xmhd " as input, obtains encrypted characters string.In the present embodiment, the length of encrypted characters string is constant, i.e. 5 bytes.Character string after encrypting is divided into
individual continuous numerical digit fragment, i.e. character fragment
, acquisition comprises
character string
, character fragment
figure place be its length
.Consider character fragment for safety
also can do further encryption, in the present embodiment, omit.The length of compute vectors figure
with character string length
ratio, and round downwards
；
In the present embodiment,
,
represent can effectively embed in the present embodiment
group character string.
Step 1.2
Know and know, the essence of vector graphics is mathematical function image, no matter be line segment, multi-section-line, SPL, circular arc etc. pel, all to draw by necessary parameter the functional picture forming, so from the angle of function, primitive types can be regarded as type function, and the geometric properties of pel can be regarded as function parameter.
As shown in Figure 1, handle value is given according to the time sequencing of primitive generating by plotter program, arrange in chronological order, there is uniqueness, primitive attribute mark the type (being type function) of the contained pel of this segment data, include but not limited to line segment, multi-section-line, SPL, circular arc, polygon, ellipse, cloud line etc.
In Fig. 1, primitive information part has been recorded the geometric properties (function parameter) of corresponding pel (type function), for different primitive types, primitive information part has been recorded the intrinsic call parameter of the type function, for example starting point, terminal, intermediate point, node, the center of circle, start angle, termination point, radius, knot vector etc.
In Fig. 1, out of Memory part has been recorded the information of the line style, live width, color, figure layer of corresponding pel etc. non-phasor function geometric properties.
According to spirit of the present invention, tackle each pel and build complex vector operator.Now set forth the structure example of vector operator with the pel shown in Fig. 2 to Fig. 5.
As shown in Figure 2, for line segment ab, the coordinate of getting its starting point a and terminal b builds and characterizes vector
it is as follows,
,
be that a point points to the vector that b is ordered, for the ease of interpreting blueprints, Fig. 2 specially will
shift out.
As shown in Figure 3, for multi-section-line cdefgh, ignore intermediate point and only get its starting point c and terminal h coordinate structure sign vector
it is as follows,
,
to point to from c point the vector that h is ordered.
As shown in Figure 4, ignore intermediate point for SPL ijklmno and only get starting point i and terminal o structure sign vector
it is as follows,
,
to point to from i point the vector that o is ordered.
As shown in Figure 5, for circular arc pqr, ignore the center of circle and only get initial angle
, end angle
, radius R build characterize vector
it is as follows,
，
be from p point in the center of circle points to, and phasing degree is
vector.
For circle, can be regarded as initial angle and be
, end angle is
special circular arc, it characterizes structure of vector with reference to circular arc.
As mentioned above, characterizing vector can use two general formulas below to express
，
，
Formula
be applicable to only get coordinate points and build the situation that characterizes vector, formula
be applicable to extract angle and radius and build the situation that characterizes vector, as for the situation of utilizing other geometric properties (function parameter) to build to characterize vector at this without enumerating, those of ordinary skill in the art can amplify and obtain from above-mentioned publicity.
Above-mentioned formula
and formula
can close and be written as
，
By formula
can make its plural form
，
Formula
be complex vector operator.So, have
,
Formula
the euler form of complex vector operator, wherein,
Mould is long
，
Phasing degree
。
At this, the pel of a pair of adjacent order is referred to as " pel to ".
Step 1.3
Spirit according to the present invention, should be according to the right complex vector operator of the more adjacent order pel of the generation order of pel (handle value), can be according to the order comparison from small to large of handle value, and also can be according to handle value order from big to small.That its mode relatively can be taked to do is poor, do the computings such as business, and the present embodiment is done business mode taking complex vector operator explains as example.The complex vector operator of adjacent order is obtained as business
,
Be that the long ratio of mould is
,
Phase differential is
，
with
be referred to as front plural ratio
so, to getting
or get
participate in follow-up computing and depend on intention; For example, can be in front plural ratio
special result choose, work as
time, choose
as the front plural ratio of adding character fragment
, when
time, choose
as the front plural ratio of adding character fragment
; Also such as, can be in front plural ratio
size choose, work as
time, choose
as the front plural ratio of adding character fragment
, vice versa.The present embodiment will be according to front plural ratio
size choose
or
participate in follow-up computing.
Due to the limitation of computer resource, operation result can only represent with limited figure place, determine the limited of its precision.In order to improve the precision of calculating as far as possible, should select the data type storage calculated factor of high precision.Conventional double-precision floating points is a kind of high-precision data type, as shown in Figure 6, the double-precision floating points of IEEE-754 standard definition, its high 63 is-symbol position S, 62～52 is exponent bits E, low 0～51 Wei Shi mantissa position
.According to the present invention's spirit, in the present embodiment, front plural ratio, middle plural ratio and rear plural ratio and extract plural ratio and all will save as double-precision floating point data.
Step 1.4
According to the present invention's spirit, by character fragment
be embedded into front plural ratio
after can obtain new plural ratio, be referred to as middle plural ratio
.Concrete embedded mode has multiple, comprises that the first object of reference decides character fragment
be embedded into
position in the position M of mantissa, as choose primitive types as reference, different primitive types is embedded into different positions; Comprise that the second can adopt the mode of fixed position by character fragment
be embedded into
mantissa position
in.The present embodiment will adopt mode in second to carry out illustrated example.As shown in Figure 6,
mantissa position
in choose
position is arrived
between position
position is interval embeds interval as character fragment
, character fragment embeds interval
position choose with not excessively destroy
precision be advisable with, to embed character fragment
after vector graphics distortion within reason cause interpreting blueprints error for considering, do not change as far as possible
initial value, ensure mark pel size numerical value constant be bottom line.
Step 1.5
According to the present invention's spirit, should basis
amendment pel pair, makes amended pel to the rear plural ratio of plural ratio
equal middle plural ratio
; The present invention simultaneously points out preferably only to revise pel centering order pel formerly, and the present embodiment adopts amendment pel centering order figure element plan formerly.
As shown in Figure 7, certain pel, to being made up of pel 20 and pel 30, from handle value, supposes that pel 20 is order pels formerly, existing by certain character fragment
embed in pel 20.As previously mentioned, calculate the ratio of the complex vector operator of pel 30 and pel 20
,
with
.Suppose
, get
for front plural ratio
, use character fragment
replace
character in the position M of mantissa embeds interval
,
.Then, keep pel 20 each points constant, only revise terminal
for
point, will characterize vector
be revised as
, make
with
meet
，
Complete character fragment
embedding.
As shown in Figure 8, certain pel, to being made up of pel 40 and pel 50, from handle value, supposes that pel 40 is order pels formerly, existing by certain character fragment
embed in pel 40.As previously mentioned, calculate the ratio of the complex vector operator of pel 50 and pel 40
,
with
.Suppose
, get
for front plural ratio
, use character fragment
replace
character in the position M of mantissa embeds interval
,
.Then, keep center of circle p, radius R, initial angle constant, only amendment
point is
point, will characterize vector
be revised as
, make
with
meet
，
Complete character fragment
embedding.
Step 1.6
According to the spirit of invention, embed the elaboration of character fragment according to earlier figures 7 and Fig. 8, as long as travel through all pels pair by the order of handle value, by character chip sequence
institute comprise each fragment (
) be embedded into one by one in corresponding pel, embed first last character fragment
after, then from first character fragment
start, the handle position, place of continuing continues to embed, and so circulation, until all
individual pel has all embedded character fragment
till, complete embedding step.
All described in the present embodiment
individual pel is to be general reference, be difficult to by figure expressions of give an example, for show embed before and after the variation of pel, now plan with 12 pels of Fig. 9 count into
, and the change of exaggeration embedding front and back is shown it with image.
In Fig. 9,
the vector graphics of character fragment to be added,
the vector graphics that has added character fragment, vector graphics
all pels all embedded character fragment
, obtain the vector graphics that comprises character fragment
.The pel of label 01～12 mark is respectively: line segment 01, SPL 02, line segment 03, line segment 04, circular arc 05, circle 06, line segment 07, line segment 08, line segment 09, line segment 10, multi-section-line 11, multi-section-line 12.Label 01～12 is combined into vector graphics
, represent with heavy line; The upper target pel of band " W " is combined into vector graphics
, represent with thick dashed line.
Two, extract
Step 2.1 is to step 2.3
According to the present invention's spirit, extract character fragment and should be each pel structure complex vector operator.What the present embodiment adopted in the time adding character is only to revise order pel formerly, instantly (is operating) pel centering order pel formerly
be to the posterior pel of order, to pel centering order pel formerly instantly in back pel
embed character fragment
time change back
in
value, if cause in the time extracting according to identical traversal order traversal when embedding, what calculate is
, instead of
.So the present embodiment extracts the traversal order of character fragment should contrary with the traversal order that embeds character (starting point of extracting be the terminal embedding), and inverse goes out
.
Taking Fig. 9 as example, embedding be last pel of traversing to being pel 11-pel 12, due to multi-section-line 12 posterior pel of pel centering order in finally traversing in the time embedding, its value is not affected by embedding operation, extracting traversal ought be from pel 12 and pel
start, first calculate
, obtain
can embed from its character interval
in read last character fragment
.
Extraction traverse second pel to time, Ying Xianyou
.First, erase
in character embed interval
, obtain the new plural ratio of erase character fragment
be referred to as " inverse plural number ratio "; Secondly, amendment multi-section-line
, its function parameter being modified (the present embodiment is terminal) is identical with embedding Modification growth function parameter, and after amendment, inverse goes out multi-section-line
, and make multi-section-line
meet
，
Inverse finishes.
Due to
be
middle erase character embeds interval
and obtain,
, its corollary is multi-section-line
do not overlap with multi-section-line 11,
.Its error
be referred to as " natural distortion ", natural distortion unavoidably but controlled.Character fragment
length
less, smear rear natural distortion
just less, character embeds interval
the position lower (the closer to lowest order) being positioned, smears rear just less on the impact of initial value; So, control character fragment
the degree of refinement of cutting apart and character embed interval
position, can control nature distortion
size.
Calculate
after, by pel
regard pel 11 as, calculate
.Due to
very little,
，
Even
，
It is interval that but the character that does not mean that them embeds
unequal.Embed interval for concrete character
position and the degree of refinement cut apart of character fragment,
in a scope of allowing time,
character embed interval
be believable, read and complete the character fragment right to this pel
extraction.
Traverse the 3rd pel to after starting from extraction, traverse second operation that pel is right with reference to extracting.Suppose instantly to traverse
individual pel and
the pel pair of individual pel composition, a upper extraction pel is to by the
pel and
pel composition calculates in upper one extracts operation
, for instantly extracting operation, only need to be coated with and erase
character fragment embed interval
, obtain inverse plural number ratio instantly
.Revise pel instantly
, obtain amended pel
, and make pel
and pel
meet
，
Again by pel
regard pel as
, calculate
,
From
middle reading character fragment
.
As previously mentioned, extract traverse each pel to time all can be subject to a upper pel pair
impact, along with extract traversal carrying out, each pel to produce
conduct downwards in capital, makes
constantly amplify.When
while being amplified to a certain degree, so far will have influence on later
character embed interval
confidence level, will
character embed interval
when insincere for the first time, residing traversal is defined as " traversal of breaking one's promise (V) ", traversing all traversal numbers of (comprising end points) before the traversal of breaking one's promise and is referred to as " credible traversal number (NV) " by extracting for the first time.
The present embodiment vector graphics general reference
individual pel, total completes
inferior embedding, embeds at least
individual complete character string
(
round downwards and obtain), in order to ensure
character embed interval
always credible, character string
length
and must meet between credible traversal number (NV)
，
Often complete once
individual extraction, what the next one extracted is complete character sequence
most end trailing character fragment
.Due to
in one group embeds, in end, extract
shi Wuxu inverse can directly extract, and extracting mode is referring to aforementioned last character fragment
extraction.Extract character fragment
until to character fragment
, all must adopt inverse to extract, its extracting mode is referring to aforementioned.
The present embodiment vector graphics general reference
individual pel, the
the most end trailing character fragment of group
to last character fragment of whole embedding step
between pel number between
between individual, be difficult to determine from extracting traversal starting point, extract and just extract several times the
the most end trailing character fragment of group
so, should do
inferior complete extraction traversal; Travel through each time than last time traversal, from traversal starting point to supposition the
group most end trailing character fragment
between equal difference once extract; To ensure
in individual complete extraction traversal, must there is a traversal to the
the most end trailing character fragment of group
definite be correct, this traversal is referred to as " extract just travel through ".In theory, extract just all over obtaining the correct characters fragment that number is maximum;
within the specific limits, other extract the correct characters fragment number that obtains of traversal be not necessarily less than extraction just traveling through the correct characters fragment number arriving.
the sum of the character fragment that inferior traversal obtains forms sample.
Step 2.4
Analyzing samples by each character fragment and correct character string comparison, can match in character string, is correct character fragment, is retained; What can not match will not retain.The character fragment frequency that statistics remains into, is zero if there is the frequency of character fragment, illustrates that the interference attack suffering is overweight, extracts unsuccessfully, if the frequency of all character fragments is all non-vanishing, can correctly restore copyright character.
Step 2.5
By good each character fragment string, by decryption processing, restore copyright character " #xmhd ".
Embodiment bis-
One, embed
The present embodiment is than embodiment mono-, and step 1.1～step 1.4 is identical; From step 1.5, different, embodiment mono-is amendment pel centering order pel formerly, and the present embodiment is amendment pel centering, the posterior pel of order, and difference thus, the extraction step of the present embodiment and have difference.When the present embodiment embeds traversal, also according to character string
embed one by one, embedded one group of characters
rear continuation embeds traversal point and continues to embed new one group of character string
, with embodiment mono-, after the present embodiment has embedded, in whole vector graphics, comprise
individual complete character string
.
This enforcement plan is with 12 pels of Figure 10 to exaggerate it, and signal pel is in the change that embeds front and back.What the present embodiment was revised is the posterior pel of pel centering order, and than Fig. 9 of embodiment mono-, the present embodiment has lacked
, many
;
Two, extract
Because the present embodiment has been selected the posterior pel of amendment pel centering order, compared with embodiment mono-, the present embodiment completes after embedding, directly calculate the right plural ratio of pel and can extract character fragment, extract without inverse, the order identical with embedding traversal order (the starting point of extracting traversal is the starting point that embeds traversal) of extracting traversal, and unnecessary doing
inferior traversal.
Obtain after the sample of this enforcement, generally only need to add up the frequency that each character fragment occurs, fall wrong character fragment by threshold filtering, retain correct character fragment group string.If know clearly encryption while embedding, after deciphering, restore copyright character " #xmhd ", directly obtain copyright character " #xmhd " if do not do the encryption process;
Embodiment tri-
The present embodiment does not lie in to exemplify and embeds and extract, and how the present embodiment can resist geometric attack if mainly being set forth the present invention, why interference attack is had to robustness;
One, the opposing of geometric attack
Geometric attack refers to whole vector graphics is done to convergent-divergent of overall importance, rotation, translation or combinations thereof operation, destroys with intention after revising pel function parameter the character fragment being embedded in function parameter; After convergent-divergent of overall importance, rotation, translation or its combination operation, although pel function parameter changes, figure entirety is constant, does not impact, therefore the method is first choice of assailant to reading;
The present invention builds complex vector operator, calculate pel to plural ratio, and character fragment is embedded in rear plural ratio, as long as the mould of the sign vector of each pel is long and phasing degree is constant, the character fragment in plural ratio is constant thereafter.The operation of convergent-divergent, rotation, translation or its combination, all belongs to linear transformation, the right plural constant rate of same pel before and after conversion, i.e. and rear plural constant rate before and after conversion, what character fragment was not converted affects, and can resist geometric attack completely;
Previous embodiment one and embodiment bis-, as setting forth exemplifying of the present invention, can resist geometric attack completely;
Two, the robustness of interference attack
Interference attack refers to adding, delete or amendment pel, and combination operation; To destroy the mode of pel, the calculating based on pel is cut off, extract confusion and cause, disturb and extract result.Implement interference attack person, also can consider the destruction disturbing former figure, for example, add pel, should be taken into account whether the pel being added to can affect reading, cause the value of figure to be difficult to embody if impact is read, the meaning of its attack is also all gone.Equally, amendment or deletion pel also should be considered attack result and whether can cause the conversion of figure and depart from original design idea, if cause the loss of original design idea, not only lose the meaning of attack, more may change the disastrous effect causing by Design Imported.As can be seen here; even if the excessive character fragment that causes of interference attack intensity cannot extract, also often cause figure to be worth without depositing because of attack itself, when figure is worth without depositing or even introduce after purposes risk; for the owner of figure, its copyright protection also loses meaning.Thus, significant interference attack is only the meaning of robustness of the present invention, and those interference attack unintentionally, even if the present invention does not possess robustness to its attack, also do not mean that the protection of copyright will under fire affect.
Suppose embodiment mono-to implement to add to attack.Because being later than embodiment mono-pel, the pel being added to generates, after its handle value comes embodiment mono-pel.Embodiment mono-does in the time extracting
inferior complete extraction traversal, has added how many pels no matter add to attack,
in inferior complete extraction traversal, extract and just travel through and certainly exist, as for extracting just traveling through be
which in inferior complete extraction traversal, relevant with the pel number adding.According to the method for sample analysis of embodiment mono-, must correctly restore copyright character " #xmhd ", add to attack originally and keep out completely.
Suppose that mono-implementation modification is attacked to embodiment.Owing to having at least
organize complete characters, each complete character string is being extracted
time do not rely on prev word symbol sequence
inverse, and there is independence between group.Amendment is attacked posterior pel in that group that only can cause revising pel loca and is lost inverse basis, manufactures wrong character fragment, and the pel outside the group of amendment pel place is unaffected.
as long as there is one group attacked by amendment in group,
in inferior traversal, must once just extract and travel through, according to the method for sample analysis of embodiment mono-, must correctly restore copyright character " #xmhd ".If it is wide that practical range is attacked in amendment, in other words
large not, can not resist amendment and attack, therefore embodiment mono-can resist amendment attack under certain condition, amendment is attacked and had robustness.
Suppose embodiment mono-to implement to delete to attack.Same deletion attack, deletion is attacked posterior pel in that group that only can cause deleting pel loca and is lost inverse basis, manufactures wrong character fragment, and the pel outside the group of deletion pel place is unaffected.
as long as there is one group not suffered to delete attack in group,
in inferior traversal, must once just extract and travel through, according to the method for sample analysis of embodiment mono-, must correctly restore copyright character " #xmhd ".Attack practical range if delete wide, in other words
large not, can not resist to delete and attack, therefore embodiment mono-can resist deletion attack, there is robustness to deleting to attack under certain condition.
Suppose embodiment bis-to implement to add to attack.Because embodiment bis-does not need can directly to calculate pel through inverse in leaching process, plural ratio is obtained to character fragment, after the pel of attacking again will be arranged in by handle, add due to interpolation
individual pel only produces
the character fragment of individual mistake.According to the method for sample analysis of embodiment bis-, as long as threshold value is greater than
, to add and attack filtrations that will be done of the error character fragment that produces, interpolation attack can be resisted completely, must correctly restore copyright character " #xmhd ".In the time that interpolation is attacked too acutely, the pel number being added to even exceeds the length of former vector graphics
, use the method for sample analysis of embodiment bis-to lose efficacy; Now, use the matching process in embodiment mono-sample analysis instead, can also correctly restore copyright character " #xmhd ", add to attack and resisted completely.
Suppose that bis-implementation modifications are attacked to embodiment.Because embodiment bis-does not need can directly to calculate pel through inverse in leaching process, plural ratio is obtained to character fragment, amendment is attacked and only can be caused modifying point place pel to occurring wrong character fragment, as for unaffected outside modifying point.Attacking due to amendment is to reduce the make the mistake increase of character number of chips of correct characters number of chips, in the time that amendment is attacked too acutely, the frequency of correct character fragment may not reach the reserve of threshold value, and the copyright character " #xmhd " that causes reducing is failed.Suppose that amendment attack has changed embodiment bis-each group character strings
first pel pair, will cause losing the basis of extracting computing; But,
as long as there is one group attacked by amendment in group, according to the method for sample analysis of embodiment mono-, must match correct character fragment, successfully reduce copyright character " #xmhd ".Embodiment bis-can only resist amendment under certain condition and attack, and amendment is attacked and had robustness.
Suppose embodiment bis-to implement to delete to attack.Delete to attack only can cause and delete some place pel to occurring wrong character fragment, unaffected as for deleting outside point.Owing to deleting, to attack be to reduce the make the mistake increase of character number of chips of correct characters number of chips, in the time that deletion is attacked too acutely, the frequency of correct character fragment may not reach the reserve of threshold value, and the copyright character " #xmhd " that causes reducing is failed.Suppose to delete to attack and changed embodiment bis-each group character strings
first pel pair, will cause losing the basis of extracting computing; But,
as long as there is one group not suffered to delete and attack in group, according to the method for sample analysis of embodiment mono-, must match correct character fragment, successfully reduce copyright character " #xmhd ".Embodiment bis-can only resist under certain condition to delete and attack, and has robustness to deleting to attack.
Suppose the combination attacks of adding, revising, delete implementing, as previously mentioned, embodiment mono-and embodiment bis-have robustness to independent interference attack, for combination attacks, as long as
in group, there is one group not attacked, when sample analysis, must match complete character string, to the intrinsic robustness of combination attacks.
By the elaboration of above-described embodiment, the present invention is clear, and open fully full and accurate, those of ordinary skill in the art implement the present invention and obtain producing effect again of the present invention.Any those of ordinary skill in the art, the apparent amendment that the present invention is made all should be regarded the category that does not depart from the present invention as, and protection scope of the present invention is as the criterion with claims.
Claims (10)
1. the embedding of vector graphics copyright character and extracting method, is characterized in that comprising embedding step and extraction step, embeds step and comprises:
Step 1.1, structure copyright character string, the character object that represents copyright information is divided into continuous fragment, be called " character fragment ", the number of character fragment is the length of character string, wish embeds the pel number comprising in vector graphics is the length of this vector graphics, the length that is shorter in length than vector graphics of character fragment;
Step 1.2, the pel comprising for vector graphics builds complex vector operator;
Step 1.3, according to the right complex vector operator of the more adjacent order pel of the generation order of pel (handle value), obtains pel to plural ratio, and this step comparative result is called " front plural ratio ";
Step 1.4, by the part in the front plural ratio of character fragment replacement step 1.3, obtains the new plural ratio that embeds character fragment, is called " middle plural ratio ";
Step 1.5, the middle plural ratio amendment pel pair obtaining according to step 1.4, after amendment, the right plural ratio of this pel is called " rear plural ratio ", and amendment result should make rear plural ratio equal middle plural ratio;
Step 1.6, to step 1.5, is embedded into character fragment the pel centering traversing according to generation order (handle value) traversal step 1.1 of pel one by one;
Extraction step comprises the following steps:
Step 2.1, the pel comprising for vector graphics builds complex vector operator;
Step 2.2, according to the complex vector operator of the more adjacent order pel of the generation order of pel (handle value), obtains pel to plural ratio, is called " extracting plural ratio ", reading character fragment from extract plural ratio;
Step 2.3, to generating order (handle value) traversal step 2.1 to step 2.2, obtains the sample of character fragment composition according to pel;
Step 2.4, analyzing samples, determines correct character fragment and error character fragment;
Step 2.5, is reduced into character by correct character fragment.
2. the method for claim 1, is characterized in that embedding in step copyright character or character fragment and did the encryption process before embedding.
3. the method for claim 1, is characterized in that embedding the privileged site in the front plural ratio of copyright character replacement in step.
4. the method for claim 1, it is characterized in that embedding in step, revise pel to time, only revise pel centering order pel formerly.
5. the method for claim 1, it is characterized in that embedding in step, revise pel to time, only revise the posterior pel of pel centering order.
6. the method for claim 1 to 5 any one, is characterized in that embedding the length of vector graphics and the length ratio of character string in step and is more than or equal to 2.
7. the method for claim 6, is characterized in that embedding in step front plural ratio and middle plural ratio and rear plural ratio and is stored as double-precision floating points.
8. the method for claim 1, is characterized in that the traversal direction of the traversal direction extracted in extraction step and embedding is contrary.
9. the method for claim 1 or 8, is characterized in that the frequency that in extraction step, in analyzing samples, each character fragment occurs, with threshold filtering error character fragment, retains correct characters fragment.
10. the method for claim 1 or 8, is characterized in that in extraction step sample and correct character fragment to compare, using character fragment consistent comparative result as correct characters fragment.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111274557A (en) * | 2020-01-19 | 2020-06-12 | 广州数智网络科技有限公司 | Robust reversible watermarking algorithm for copyright protection of 2D vector graphics |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20050105760A1 (en) * | 2001-12-14 | 2005-05-19 | Eggers Joachim J. | Data embedding and extraction |
| CN103366335A (en) * | 2013-07-17 | 2013-10-23 | 兰州交通大学 | Vector point spatial data full-blind watermarking method based on grid dividing |
-
2014
- 2014-06-12 CN CN201410258892.5A patent/CN104166956B/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20050105760A1 (en) * | 2001-12-14 | 2005-05-19 | Eggers Joachim J. | Data embedding and extraction |
| CN103366335A (en) * | 2013-07-17 | 2013-10-23 | 兰州交通大学 | Vector point spatial data full-blind watermarking method based on grid dividing |
Non-Patent Citations (2)
| Title |
|---|
| 康菁菁等: "二维工程图中基于分数傅里叶变换的盲水印算法", 《计算机应用》 * |
| 汪亚顺等: "基于二维工程图的数字水印比例算法", 《南昌大学学报（工科版）》 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111274557A (en) * | 2020-01-19 | 2020-06-12 | 广州数智网络科技有限公司 | Robust reversible watermarking algorithm for copyright protection of 2D vector graphics |
| CN111274557B (en) * | 2020-01-19 | 2020-10-16 | 广州数智网络科技有限公司 | Robust reversible watermarking method for copyright protection of 2D vector diagram |
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