CN102629323A - Color image binarization and hiding and recovery method of binarization color image - Google Patents

Abstract

A binarization method of a color image comprises the following steps: (1) selecting a source image, acquiring chromatic values of red, green and blue three components of each pixel point of the source image and calculating a brightness value of the source image; (2) calculating an average brightness of the source image; (3) using a Zadeh-X transformation method to carry out binarization transformation on the red, green and blue three components of the source image so as to generate the transformed color image, and calculating the average brightness of the transformed color image; (4) comparing the average brightness of the source image with the average brightness of the transformed color image and determining a result image of the binarization transformation. The method of the invention has the following advantages that: binarization processing can be performed based on the color image so as to obtain the actual binarization color image; and compared to the source image, the binarization color image has little change in brightness.

Description

Hiding and restoration methods of the binaryzation of coloured image and binaryzation coloured image

Technical field

The invention belongs to technical field of image processing, is to make coloured image under the constant situation of brightness, carry out the method for binary conversion treatment to coloured image.

Background technology

Binary image is meant the image that two gray values are only arranged.Image binaryzation is meant the gray abundant image is transformed into the process of having only two gray values.Because binary image is simple; Data volume is little; Can highlight the profile of interested target, therefore in Digital Image Processing, occupy important status, be widely used in every field; As: optical character recognition technology OCR (optical character recognition), the processing again of document etc.

And the world is riot of color, so most of image that people obtain all is colored.The coloured image binaryzation has two kinds of thinkings always: first kind is with carrying out binary conversion treatment behind the coloured image gray processing again, and second kind is directly to carry out based on coloured image.Because the color image information amount is big, how the coloured image of binaryzation defines the also unified saying of neither one, so the second way does not obtain good effect.The technology of main flow remains the employing first method at present; But carrying out the image that binary conversion treatment obtains behind the gray processing again is black white image; It is not traditional coloured image; And gray processing diminishes, and the quality of image has also determined next step to carry out the effect of binary conversion treatment behind the gray processing.Up till now, do not have the technological means of second kind of thinking, promptly can't realize direct binary conversion treatment based on coloured image.Because binary image often contains crucial information, need in information transmission, hide and recover to handle, also be the focus of association area researchist research therefore for hiding of binaryzation coloured image.

Summary of the invention

One of the object of the invention is to propose a kind of direct coloured image binarization method based on coloured image, and the binary image that adopts this method to obtain remains coloured image, and the brightness of image is constant after the conversion.

The binaryzation coloured image that relates among the present invention is meant that three color components of red, green, blue all have the coloured image of two identical chromatic values.Fig. 7 is the width of cloth binaryzation coloured image a), Fig. 7 b) be Fig. 7 colourity spectrum a).

For reaching the object of the invention, the present invention proposes a kind of binarization method of coloured image, and its key is to comprise the following steps:

(1) step 1, selecting coloured image is source images Si, obtain three kinds of components of red, green, blue of each pixel of source images chromatic value R (x, y), G (x, y), B (x, y), and the brightness value Gray of calculation sources image (x, y);

In the practical application, brightness value is equal to gray-scale value.

(2) step 2, the mean flow rate AGSi of calculation sources image, said mean flow rate AGSi can be obtained by following formula:

$\mathrm{AGSi}=\frac{1}{M\×N}\underset{y=0}{\overset{N-1}{\mathrm{\Σ}}}\underset{x=0}{\overset{M-1}{\mathrm{\Σ}}}\mathrm{Gray}(x,y)$

In the following formula, (x is that (x, brightness value y), M, N are respectively the pixel count of source images in X, Y direction to the source image pixels point y) to Gray;

(3) step 3 utilizes the Zadeh-X transform method that three components of red, green, blue of source images are carried out the binaryzation conversion, the coloured image Di after the generating transformation and calculate this conversion after the mean flow rate AGDi of coloured image Di;

Said Zadeh-X transform method is following:

$T(k,x,y)=k\frac{O(x,y)-\mathrm{Theta}}{\mathrm{Delta}}$

Constraint condition is: $T(k,x,y)=\left\{\begin{array}{cc}k,& T(k,x,y)>k\\ 0,& T(k,x,y)<0\end{array}\right.$

In the following formula, O (x, y) chromatic value of three kinds of components of red, green, blue of expression source images; T (k, x, y) chromatic value of three kinds of components of red, green, blue of coloured image Di after the expression conversion; Delta=1, k are 1～255 integer, and Theta is 0～255 integer;

The value of different k can obtain the wide colored binary image of different colourity bands of a spectrum, and when getting k=255, the coloured image Di after the conversion of generation has maximum bandwidth, can obtain the bianry image of best quality like this.

At k is under the situation of definite value, and in the value of 0～255 scope interscan Theta, Theta whenever gets a value, the mean flow rate AGDi of coloured image Di after the corresponding conversion;

(4) step 4, definite result images of protecting the conversion of brightness binaryzation, its concrete grammar is following:

The mean flow rate AGDi of coloured image Di after each conversion and the mean flow rate AGSi of source images are compared; The mean flow rate AGDi of coloured image Di after the immediate conversion of mean flow rate AGSi of search and source images; And the corresponding Theta value of definite this AGDi; Coloured image Di after the pairing conversion of this Theta is for protecting the result images of brightness binaryzation conversion, i.e. binaryzation coloured image.

Adopt technical scheme of the present invention to handle the image that obtains and remain coloured image, three color components of the red, green, blue of this coloured image all have two identical chromatic values.Compare with source images, the coloured image brightness after the binaryzation remains unchanged basically, and the visual effect of therefore giving the people is very near source images.

Carry out the binaryzation conversion behind the coloured image gray processing again, the color level that makes image is from 2 ²⁴Dropped to 2, and guarantor's brightness binaryzation conversion of coloured image, the color level that makes image is from 2 ²⁴Dropped to 2 ³, having kept and also improved contrast colored the time, key message is able to preserve, and has increased a kind of new picture format: 2 ³The position bitmap format.

When scanning Theta; Can adopt the method for exhaustion; Scan each Theta value; Obtain coloured image Di after 256 conversion, corresponding 256 mean flow rate AGDi wherein promptly are regarded as satisfying the binaryzation coloured image of guarantor's luminance transformation with the minimum corresponding binaryzation coloured image of AGDi of source images mean flow rate AGSi difference.

In order to accelerate the sweep velocity of Theta; In said step 3 and step 4, can be by following sequential scanning Theta: 127 to be starting point, from the off by increase at every turn 1 or 1 the mode of subtracting change; Every variation once; Obtain the mean flow rate AGDi of coloured image Di after the corresponding said conversion, the mean flow rate AGSi of this AGDi and source images is compared definite Theta direction of scanning near source images mean flow rate AGSi.

Concrete operations are:

The threshold value A GT of the suitable luminance difference of image after a given source images and the conversion makes the difference P of mean flow rate AGSi of mean flow rate AGDi and source images of coloured image after the conversion satisfy:

P＝|AGDi-AGSi|≤AGT

To a scanning direction time, P is greater than AGT, and P increases along with the variation of Theta, then abandons the scanning of this direction.

Two of the object of the invention provides a kind ofly to be hidden and restoration methods what the binaryzation coloured image carried out, can hide and recovers the binaryzation coloured image that generates.

For realizing above-mentioned purpose, the binaryzation coloured image that the present invention is directed to above-mentioned generation proposes a kind of hiding and restoration methods, and its key is to carry out according to the following steps:

Step 1, selecting the binaryzation coloured image is source images, obtains the chromatic value R (x of three kinds of components of red, green, blue of each pixel of source images; Y), G (x, y), B (x, y); And the maximum of confirming three kinds of component chromatic values of red, green, blue of said source images is b, and reckling is a;

Step 2, utilize the Zadeh-X transform method respectively to the chromatic value R of three kinds of components of red, green, blue of each pixel of source images (x, y), G (x; Y), B (x; Y) carry out conversion, realization is hidden source images, obtains to hide the unresolvable coloured image of back human vision;

Said Zadeh-X transform method is following:

$T(k,x,y)=k\frac{O(x,y)-\mathrm{Theta}}{\mathrm{Delta}}$

Constraint condition is:

$T(k,x,y)=\left\{\begin{array}{cc}k,& T(k,x,y)>k\\ 0,& T(k,x,y)<0\end{array}\right.$

In the following formula, O (x, y) chromatic value of three kinds of components of red, green, blue of expression source images; (y) chromatic value of three kinds of components of red, green, blue of back binaryzation coloured image is hidden in expression to T for k, x; Delat, k, Theta are the transformation parameter of round numbers, Delta=1,0＜k≤10, a≤Theta＜b;

In the said Zadeh-X conversion, the transformation parameter of each pixel is identical;

Step 3 is utilized said Zadeh-X transfer pair to hide the back coloured image and is recovered, the image after obtaining to recover, and the image after this recovers is identical with source images;

When carrying out said Zadeh-X conversion, transformation parameter value respectively is: Delta=1, and k=255, Theta=hides the left side dividing value of back image.

Remarkable result of the present invention is: provide a kind of based on the coloured image binarization method of coloured image and the method that the binary image that generates is hidden and recovered; Utilize the brightness of the binaryzation coloured image that this binarization method generates approaching with the source images ten minutes; And be coloured image truly, on the basis of Zadeh-X conversion, also realized hiding and excavation to this binaryzation coloured image.

Description of drawings

Fig. 1 is the source images among the embodiment 1, comprises two width of cloth source images (a) and (b), and wherein the mean flow rate of (a) is 110.0884, and mean flow rate (b) is 49.0451;

Fig. 2 carries out the result images after the binary conversion treatment to Fig. 1, and wherein (a) is the result images of Fig. 1 (a), and mean flow rate is 110.7047; (b) be the result images of Fig. 1 (b), mean flow rate is 49.5710;

Fig. 3 is the process flow diagram of embodiment 1;

Fig. 4 (a) is the image after Fig. 2 (a) is hidden;

Fig. 4 (b) is the image after Fig. 2 (b) is hidden;

Fig. 5 (a) is the image after Fig. 4 (a) is recovered;

Fig. 5 (b) is the image after Fig. 4 (b) is recovered;

Fig. 6 is the process flow diagram of embodiment 2;

Fig. 7 is the colourity spectrum of binaryzation coloured image and this binary image, wherein, a) is a width of cloth binaryzation coloured image, b) is the colourity spectrum of three color components of red, green, blue a) from top to bottom successively.

Embodiment

Below in conjunction with accompanying drawing and specific embodiment the present invention is done further explain.

Embodiment 1: a kind of binarization method of coloured image, comprise the following steps, as shown in Figure 3:

(1) step 1, selecting two width of cloth coloured images shown in Figure 1 is source images Si, obtain three kinds of components of red, green, blue of each pixel of source images chromatic value R (x, y), G (x, y), B (x, y), and the brightness value Gray of calculation sources image (x, y);

(2) step 2, the mean flow rate AGSi of calculation sources image, said mean flow rate AGSi can be obtained by following formula:

$\mathrm{AGSi}=\frac{1}{M\&times;N}\underset{y=0}{\overset{N-1}{\mathrm{\&Sigma;}}}\underset{x=0}{\overset{M-1}{\mathrm{\&Sigma;}}}\mathrm{Gray}(x,y)$

In the following formula, (x is that (x, brightness value y), M, N are respectively the pixel count of source images in X, Y direction to the source image pixels point y) to Gray;

(3) step 3 utilizes the Zadeh-X transform method that three components of red, green, blue of source images are carried out the binaryzation conversion, the coloured image Di after the generating transformation and calculate this conversion after the mean flow rate AGDi of coloured image Di;

Said Zadeh-X transform method is following:

$T(k,x,y)=k\frac{O(x,y)-\mathrm{Theta}}{\mathrm{Delta}}$

Constraint condition is:

$T(k,x,y)=\left\{\begin{array}{cc}k,& T(k,x,y)>\mathrm{<figure-callout\; id="0"\; label="k"\; filenames="HSA00000671485900051.png"\; state="\{\{state\}\}">k</figure-callout>}\\ 0,& T(k,x,y)<0\end{array}\right.$

In the following formula, O (x, y) chromatic value of three kinds of components of red, green, blue of expression source images; T (k, x, y) chromatic value of three kinds of components of red, green, blue of coloured image Di after the expression conversion; Delta=1, k are 1～255 integer, and Theta is 0～255 integer;

The value of different k can obtain the wide colored binary image of different colourity bands of a spectrum, and when getting k=255, the coloured image Di after the conversion of generation has maximum bandwidth, and the visual quality of the binary image of gained is best.K=255 in the present embodiment.

At k is under the situation of definite value, and in the value of 0～255 scope interscan Theta, Theta whenever gets a value, the mean flow rate AGDi of coloured image Di after the corresponding conversion;

(4) step 4, definite result images of protecting the conversion of brightness binaryzation, its concrete grammar is following:

The mean flow rate AGDi of coloured image Di after each conversion and the mean flow rate AGSi of source images are compared; The mean flow rate AGDi of coloured image Di after the immediate conversion of mean flow rate AGSi of search and source images; And the corresponding Theta value of definite this AGDi; Coloured image Di after the pairing conversion of this Theta is for protecting the result images of brightness binaryzation conversion, i.e. binaryzation coloured image.

In order to accelerate the sweep velocity of Theta; In said step 3 and step 4, can be by following sequential scanning Theta: 127 to be starting point, from the off by increase at every turn 1 or 1 the mode of subtracting change; Every variation once; Obtain the mean flow rate AGDi of coloured image Di after the corresponding said conversion, the mean flow rate AGSi of this AGDi and source images is compared definite Theta direction of scanning near source images mean flow rate AGSi.

Concrete operations are:

The threshold value A GT of the suitable luminance difference of image after a given source images and the conversion makes the difference P of mean flow rate AGSi of mean flow rate AGDi and source images of coloured image after the conversion satisfy:

P＝|AGDi-AGSi|≤AGT

To a scanning direction time, P is greater than AGT, and P increases along with the variation of Theta, then abandons the scanning of this direction.

Result images after two width of cloth source images process binaryzation conversion of Fig. 1 is seen Fig. 2, and their corresponding Theta values are respectively 121,92.Compare with source images, all in 1 brightness level range, the visual effect of therefore giving the people is very near source images in the variation of the coloured image brightness after the binaryzation.

Embodiment 2: hiding and restoration methods of a kind of binaryzation coloured image, and as shown in Figure 6, carry out according to the following steps:

Step 1; Select Fig. 2 (a) and (b) shown in the binaryzation coloured image be source images, obtain three kinds of components of red, green, blue of each pixel of source images chromatic value R (x, y), G (x; Y), B (x; Y), and confirm that the maximum of three kinds of component chromatic values of red, green, blue of said source images is b, reckling is a; The a=0 of Fig. 2 (a) and Fig. 2 (b), b=255.

Step 2, utilize the Zadeh-X transform method respectively to the chromatic value R of three kinds of components of red, green, blue of each pixel of source images (x, y), G (x; Y), B (x; Y) carry out conversion, realization is hidden source images, obtains to hide the invisible coloured image of back human vision; Image after hiding is shown in Fig. 4 (a) and Fig. 4 (b).

Said Zadeh-X transform method is following:

$T(k,x,y)=k\frac{O(x,y)-\mathrm{Theta}}{\mathrm{Delta}}$

Constraint condition is:

$T(k,x,y)=\left\{\begin{array}{cc}k,& T(k,x,y)>\mathrm{<figure-callout\; id="0"\; label="k"\; filenames="HSA00000671485900051.png"\; state="\{\{state\}\}">k</figure-callout>}\\ 0,& T(k,x,y)<0\end{array}\right.$

In the following formula, O (x, y) chromatic value of three kinds of components of red, green, blue of expression source images; (y) chromatic value of three kinds of components of red, green, blue of back binaryzation coloured image is hidden in expression to T for k, x; Delat, k, Theta are the transformation parameter of round numbers, Delta=1,0＜k≤10, a≤Theta＜b;

In the present embodiment, the transformation parameter k=1 of Fig. 4 (a) and Fig. 4 (b), Theta=0.

In the said Zadeh-X conversion, the transformation parameter of each pixel is identical;

Step 3 is utilized said Zadeh-X transfer pair to hide the back coloured image and is recovered, the image after obtaining to recover, and shown in Fig. 5 (a) and Fig. 5 (b), the image after this recovers is identical with source images;

When carrying out said Zadeh-X conversion, transformation parameter value respectively is: Delta=1, and k=255, Theta=hides the left side dividing value of back image, i.e. Theta=0.

Claims (3)

1. the binarization method of a coloured image is characterized in that comprising the following steps:

(1) step 1, selecting coloured image is source images Si, obtain three kinds of components of red, green, blue of each pixel of source images chromatic value R (x, y), G (x, y), B (x, y), and the brightness value Gray of calculation sources image (x, y);

(2) step 2, the mean flow rate AGSi of calculation sources image, said mean flow rate AGSi can be obtained by following formula:

$\mathrm{AGSi}=\frac{1}{M\&times;N}\underset{y=0}{\overset{N-1}{\mathrm{\&Sigma;}}}\underset{x=0}{\overset{M-1}{\mathrm{\&Sigma;}}}\mathrm{Gray}(x,y)$

In the following formula, (x is that (x, brightness value y), M, N are respectively the pixel count of source images in X, Y direction to the source image pixels point y) to Gray;

(3) step 3 utilizes the Zadeh-X transform method that three components of red, green, blue of source images are carried out the binaryzation conversion, the coloured image Di after the generating transformation and calculate this conversion after the mean flow rate AGDi of coloured image Di;

Said Zadeh-X transform method is following:

$T(k,x,y)=k\frac{O(x,y)-\mathrm{Theta}}{\mathrm{Delta}}$

Constraint condition is:

$T(k,x,y)=\left\{\begin{array}{cc}k,& T(k,x,y)>k\\ 0,& T(k,x,y)<0\end{array}\right.$

In the following formula, O (x, y) chromatic value of three kinds of components of red, green, blue of expression source images; T (k, x, y) chromatic value of three kinds of components of red, green, blue of coloured image Di after the expression conversion; Delta=1, k are 1～255 integer, and Theta is 0～255 integer;

At k is under the situation of definite value, and in the value of 0～255 scope interscan Theta, Theta whenever gets a value, the mean flow rate AGDi of coloured image Di after the corresponding conversion;

(4) step 4, definite result images of protecting the conversion of brightness binaryzation, its concrete grammar is following:

The mean flow rate AGDi of coloured image Di after each conversion and the mean flow rate AGSi of source images are compared; The mean flow rate AGDi of coloured image Di after the immediate conversion of mean flow rate AGSi of search and source images; And the corresponding Theta value of definite this AGDi; Coloured image Di after the pairing conversion of this Theta is for protecting the result images of brightness binaryzation conversion, i.e. binaryzation coloured image.

2. the binarization method of a kind of coloured image according to claim 1; It is characterized in that: in said step 3 and step 4, can be by following sequential scanning Theta: 127 to be starting point, from the off by increase at every turn 1 or 1 the mode of subtracting change; Every variation once; Obtain the mean flow rate AGDi of coloured image Di after the corresponding said conversion, the mean flow rate AGSi of this AGDi and source images is compared definite Theta direction of scanning near source images mean flow rate AGSi;

Concrete operations are:

The threshold value A GT of the suitable luminance difference of image after a given source images and the conversion makes the difference P of mean flow rate AGSi of mean flow rate AGDi and source images of coloured image after the conversion satisfy:

P＝|AGDi-AGSi|≤AGT

To a scanning direction time, P is greater than AGT, and P increases along with the variation of Theta, then abandons the scanning of this direction.

3. one kind to the hiding and restoration methods of the described binaryzation coloured image of claim 1, it is characterized in that carrying out according to the following steps:

Step 1, selecting the binaryzation coloured image is source images, obtains the chromatic value R (x of three kinds of components of red, green, blue of each pixel of source images; Y), G (x, y), B (x, y); And the maximum of confirming three kinds of component chromatic values of red, green, blue of said source images is b, and reckling is a;

Step 2, utilize the Zadeh-X transform method respectively to the chromatic value R of three kinds of components of red, green, blue of each pixel of source images (x, y), G (x; Y), B (x; Y) carry out conversion, realization is hidden source images, obtains to hide the unresolvable coloured image of back human vision;

Said Zadeh-X transform method is following:

$T(k,x,y)=k\frac{O(x,y)-\mathrm{Theta}}{\mathrm{Delta}}$

Constraint condition is: $T(k,x,y)=\left\{\begin{array}{cc}k,& T(k,x,y)>k\\ 0,& T(k,x,y)<0\end{array}\right.$

In the following formula, O (x, y) chromatic value of three kinds of components of red, green, blue of expression source images; (y) chromatic value of three kinds of components of red, green, blue of back binaryzation coloured image is hidden in expression to T for k, x; Delat, k, Theta are the transformation parameter of round numbers, Delta=1,0＜k≤10, a≤Theta＜b;

In the said Zadeh-X conversion, the transformation parameter of each pixel is identical;

Step 3 is utilized said Zadeh-X transfer pair to hide the back coloured image and is recovered, the image after obtaining to recover, and the image after this recovers is identical with source images;

When carrying out said Zadeh-X conversion, transformation parameter value respectively is: Delta=1, and k=255, Theta=hides the left side dividing value of back image.

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