CN105245760B - A kind of antidote and its system of ccd image brightness - Google Patents
A kind of antidote and its system of ccd image brightness Download PDFInfo
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Abstract
The invention discloses the antidote and its system of a kind of ccd image brightness, wherein method includes：Left and right channel C CD image is obtained, and described image is divided into band；By strips mosaic stitch centered on select the image block of default size；Discrete cosine transform is made to described image block, and DCT high frequency coefficient is inhibited；Inverse discrete cosine transform IDCT is made to described image block.By the above-mentioned means, the present invention can be realized the influence for avoiding the brightness correction of the image of double channels acquisition to consistent state brightness from jumping to tissue physiological characteristic in DR image, the interference of diagnosis is reduced.
Description
Technical field
The present invention relates to digital medical images processing technology fields, more particularly, to a kind of correction side of ccd image brightness
Method and its system.
Background technique
DR system, i.e. direct digital radiograph system, be by electronic cassette, scanning monitor, system controller,
The composition such as image display monitor central monitoring system, is that x-ray photon is directly converted to digitized image by electronic cassette, is a kind of sensu lato straight
Connect Digital X-ray Radiotive.
Traditional CCD DR acquires image using full frame CCD, and resolution ratio is generally up to millions of pixels, since clock frequency has
Limit, huge data volume cause image acquisition process slow.With the continuous development of medical diagnosis, dynamic is proposed to DR and is adopted
The demand of collection requires acquisition multiframe in 1 second, this is that traditional CCD acquisition technique is not accomplished.Meet dynamic acquisition, it is necessary to mention
Hi-vision acquisition frame rate, big resolution ratio full frame CCD are difficult to accomplish this point by traditional technology.Healthy technological applications CCD bilateral
Road acquisition technique realizes the function of dynamic acquisition, reaches the acquisition frame rate of 8 frame per second.But since power supply, component etc. are hard
Have no idea to accomplish two channels completely the same in terms of part circuit, there are the differences in brightness for the image for causing two channels to acquire
It is different, and since CCD works in high-frequency, the feature of the response of light is changed, linearly becomes non-thread by original
Property, lead to not carry out multichannel brightness correction with traditional DR flat field correcting technology.So the invention proposes one kind to be directed to
The brightness correction method of CCD Channel Image acquisition.
Summary of the invention
The technical problem to be solved by the present invention is to：Propose a kind of brightness correction for the acquisition of CCD Channel Image
The brightness of image in left and right channel is remedied to consistent state by method, and it is uniform to be allowed to transition, to meet medical diagnosis requirement.
In order to solve the above-mentioned technical problem, the technical solution adopted by the present invention is：A kind of correction of ccd image brightness is provided
Method, including：
Left and right channel C CD image is obtained, and described image is divided into band；
By strips mosaic stitch centered on select the image block of default size；
Discrete cosine transform is made to described image block, and DCT high frequency coefficient is inhibited；
Inverse discrete cosine transform IDCT is made to described image block.
To solve the above problems, the present invention provides a kind of correction system of ccd image brightness, including：
Divide module, for obtaining left and right channel C CD image, and described image is divided into band；
Image block module, for by strips mosaic stitch centered on select the image block of default size；
DCT module for making discrete cosine transform to described image block, and inhibits DCT high frequency coefficient；
IDCT module, for making inverse discrete cosine transform IDCT to described image block.
The beneficial effects of the present invention are：Be different from the prior art, the present invention by the way that ccd image is divided into band, and
Acquisition image block is taken in item, discrete cosine transform and inverse discrete cosine transform IDCT successively are carried out to image block.Pass through
Aforesaid way, the present invention may be implemented the brightness correction of the image of double channels acquisition to consistent state avoiding brightness jump pair
The influence of tissue physiological characteristic in DR image, reduces the interference of diagnosis.
Detailed description of the invention
Fig. 1 is the flow diagram of embodiment of the present invention method one；
Fig. 2 is the flow diagram of embodiment of the present invention method two；
Fig. 3 is the structural block diagram of present system embodiment three；
Fig. 4 is the structural block diagram of present system example IV；
Fig. 5 is that specific embodiment of the invention band divides schematic diagram；
Fig. 6 is the image before specific embodiment of the invention processing；
Fig. 7 is the specific embodiment of the invention treated image.
Specific embodiment
To explain the technical content, the achieved purpose and the effect of the present invention in detail, below in conjunction with embodiment and cooperate attached
Figure is explained.
The design of most critical of the present invention is:The stitching portion of left and right channel image is converted and is corrected, and realizes brightness
Uniformity.
Fig. 1 is please referred to, the embodiment of the present invention one provides a kind of antidote of ccd image brightness, includes the following steps：
S1：Left and right channel C CD image is obtained, and described image is divided into band；
S2：By strips mosaic stitch centered on select the image block of default size；
S3：Discrete cosine transform is made to described image block, and DCT high frequency coefficient is inhibited；
S4：Inverse discrete cosine transform IDCT is made to described image block.
It is different from the prior art, the embodiment of the present invention one takes acquisition figure in item by the way that ccd image is divided into band
As block, discrete cosine transform and inverse discrete cosine transform IDCT successively are carried out to image block.By the above-mentioned means, this hair
It is bright to may be implemented to avoid brightness jump to human body group in DR image the brightness correction of the image of double channels acquisition to consistent state
The influence for knitting physiological characteristic reduces the interference of diagnosis.
As shown in Fig. 2, the embodiment of the present invention two further includes after step S1：
S11：Record the first luminance mean value of left and right channel C CD image.
Wherein, step S3 is specially：
S31：Discrete cosine transform is made to described image block, obtains the high frequency coefficient value of the first row；
S32：Obtain the rejection coefficient from 0.5 linear increment to 1；
S33：The high frequency coefficient value of the first row is multiplied with the rejection coefficient.
Wherein, after step S4, further include：
S5：Record the second luminance mean value of left and right channel C CD image；
S6：The compensation coefficient of left and right channel C CD image is obtained, and mean filter processing is carried out to two groups of compensation coefficients；
S7：The brightness of image mean value in band or so channel is multiplied with the compensation coefficient, obtains final image.
Wherein, step S6 is specially：
S61：By the second luminance mean value divided by the first luminance mean value, the correction of each band on left and right channel C CD image is obtained
Coefficient sets；
S62：Mean filter is carried out to the compensation coefficient group.
As shown in Fig. 5~7, for convenience of understanding, the above method is described in detail below by way of a specific embodiment.
Firstly, so-called DR system, i.e. direct digital radiograph system, are by electronic cassette, scanning monitor, are
The compositions such as system controller, image display monitor central monitoring system, are that x-ray photon is directly converted to digitized image by electronic cassette, are a kind of
Sensu lato direct digital mammography.
So-called discrete cosine transform (DCT for Discrete Cosine Transform) is related to Fourier transformation
A kind of transformation, it is similar to discrete Fourier transform (DFT for Discrete Fourier Transform), but only
Use real number.It is probably its twice discrete Fourier transform, this direct computation of DFT that discrete cosine transform, which is equivalent to a length,
Leaf transformation is that (because the Fourier transformation of a real even function is still a real even function) is carried out to a real even function,
The mobile half unit in the position that will be inputted or export is needed inside some deformations, and (DCT has 8 kinds of types, wherein 4 kinds are
Common).
Discrete cosine transform, especially its second of type are often used by signal processing and image procossing, for pair
Signal and image (including static image and moving image) carry out damaging data compression.This is because discrete cosine transform has very
Strong " energy concentration " characteristic:The energy of most of natural sign (including sound and image) all concentrates on discrete cosine transform
Low frequency part afterwards, and when signal have close to markoff process (Markov processes) statistical property when, from
Dissipate cosine transform decorrelation close to Karhunen-Loeve transformation (Karhunen-Loeve transformation -- it have optimal decorrelation)
Performance.
For example, in still image coding standard JPEG, in each standard of motion picture encoding standard MJPEG and MPEG
In all employ discrete cosine transform.Two-dimensional second of type discrete cosine transform is all employed in these standard systems, and
Entropy coding is carried out after result is quantified.At this moment the n corresponded in second of type discrete cosine transform is usually 8, is used in combination
The formula converts every row of each 8x8 block, and then each column is converted.What is obtained is the transformation coefficient square of a 8x8
Battle array.Wherein the element of (0,0) position is exactly DC component, and the other elements in matrix indicate the friendship of different frequency according to its position
Flow component.
After obtaining left and right channel C CD image, band is divided the image into, the height of the band in specific embodiments of the present invention
Degree is 32 pixels, and the band of red line segmentation as shown in Figure 5, each band is taken centered on splicing seams (i.e. picture centre line)
Image block, what this specific embodiment was chosen is the region of 32x32, and wherein left side 16x32, the right take 16x32, why take fixation
32x32 size is because the image information within the scope of 32x32 is approximately, to may be assumed that brightness is consistent in the range in this way
, could the right and left brightness be rectified uniformly based on the hypothesis, may include the information of more human body when greater than 32x32, it is false
If invalid, if acquirement is too small, interfered vulnerable to picture noise.
Then, discrete cosine dct transform is done to 32x32 fritter, since there are luminance differences, transition for the image in left and right channel
It is phenomena such as jump, specific as shown in Figure 6.So high frequency coefficient (i.e. the first row information) value of DCT is larger, it is this bright in order to weaken
Degree jump, needs to inhibit high frequency coefficient, and the present invention is by carrying out the first row DCT value multiplied by the rejection coefficient less than 1
Inhibit, frequency is higher, and rejection coefficient is smaller.Specifically, rejection coefficient of the invention is from 0.5 linear increment to 1, with these coefficients
With the first row DCT value dot product.In the specific embodiment of the invention, each image block is 32*32, therefore a total of 32 row,
Corresponding 32 DCT values, wherein the high frequency coefficient of the first row is maximum, therefore it needs to carry out dot product with rejection coefficient 0.5, and last
The high frequency coefficient of a line (i.e. the 32nd row) is minimum, it is therefore desirable to dot product is carried out with rejection coefficient 1, and the 2nd row is then to the 31st row
The rejection coefficient of corresponding linear relationship is selected to carry out dot product between 0.5 to 1.
And then carry out inverse discrete cosine transform IDCT.It should be understood that corresponding to discrete cosine transform；It is discrete remaining
String transformation is image to be switched to coefficient of frequency, and inverse discrete cosine transform is in order to which coefficient of frequency is switched to image, this is at image
The basic theory of reason.The brightness uniformity of entire 32x32 image block at this time, left side 16x32 and the right 16x32 brightness are without jump.
Then, the luminance mean value (i.e. the second luminance mean value) for the left side 16x32 that takes that treated is divided by the left side before processing
16x32 mean value (i.e. the second luminance mean value), obtains the compensation coefficient a1 on the band left side, similarly obtains the correction coefficient b1 on the right,
Two coefficients in the corresponding left and right of band each in this way make same processing to each band, obtain two compensation coefficient groups：{a1,
A2 ..., an-1, an }, { b1, b2 ..., bn-1, bn }, mean filter is carried out to every group of compensation coefficient, keeps coefficient smooth, this
The purpose of sample is to keep the brightness after the correction of neighbouring band excessively uniform；Finally, to each band left-right parts with
Corresponding multiplication, the right and left of such band, the luminance transition between band and band are all uniform.
The brightness correction of the image of double channels acquisition to consistent state can be avoided brightness jump in DR image by the present invention
The influence of tissue physiological characteristic reduces the interference of diagnosis.Specific effect is as shown in fig. 7, wherein Fig. 6 is without this
The image of technology correction, it is seen that there are apparent splicing seams and brightness jump in centre, and right half part is relatively darker, and Fig. 7 is by this
Same image of technology correction, effect are obviously improved, the right and left brightness uniformity, and transition is natural.
Wherein, as shown in figure 3, the embodiment of the present invention three also provides a kind of correction system 100 of ccd image brightness, including：
Divide module 110, for obtaining left and right channel C CD image, and described image is divided into band；
Image block module 120, for by strips mosaic stitch centered on select the image block of default size；
DCT module 130 for making discrete cosine transform to described image block, and inhibits DCT high frequency coefficient；
IDCT module 140, for making inverse discrete cosine transform IDCT to described image block.
Wherein, as shown in figure 4, the system 100 of the embodiment of the present invention four further includes：
First logging modle 150, for recording the first luminance mean value of left and right channel C CD image.
Wherein, the DCT module 130 includes：
DCT unit 131 obtains the high frequency coefficient value of the first row for making discrete cosine transform to described image block；
Rejection coefficient unit 132, for obtaining the rejection coefficient from 0.5 linear increment to 1；
Inhibit unit 133, for the high frequency coefficient value of the first row to be multiplied with the rejection coefficient.
Wherein, the system 100 of the embodiment of the present invention four further includes：
Second logging modle 150, for recording the second luminance mean value of left and right channel C CD image；
Compensation coefficient module 160, for obtaining the compensation coefficient of left and right channel C CD image, and to two groups of compensation coefficients into
The processing of row mean filter；
Rectification module 170 is obtained for the brightness of image mean value in band or so channel to be multiplied with the compensation coefficient
Obtain final image.
Wherein, the compensation coefficient module 160 includes：
Mean value is divided by unit 161, for the second luminance mean value divided by the first luminance mean value, to be obtained left and right channel C CD figure
As the compensation coefficient group of upper each band；
Filter unit 162, for carrying out mean filter to the compensation coefficient group.
The above description is only an embodiment of the present invention, is not intended to limit the scope of the invention, all to utilize this hair
Equivalents made by bright specification and accompanying drawing content are applied directly or indirectly in relevant technical field, similarly include
In scope of patent protection of the invention.
Claims (8)
1. a kind of antidote of ccd image brightness, which is characterized in that including：
Left and right channel C CD image is obtained, and described image is divided into band；
By strips mosaic stitch centered on select the image block of default size；
Discrete cosine transform is made to described image block, and DCT high frequency coefficient is inhibited；
Inverse discrete cosine transform IDCT is made to described image block；
After the step of making inverse discrete cosine transform IDCT to described image block, further include：
Record the second luminance mean value of left and right channel C CD image；
The compensation coefficient of left and right channel C CD image is obtained, and mean filter processing is carried out to two groups of compensation coefficients；
Second luminance mean value of band or so channel C CD image is multiplied with the compensation coefficient, obtains final image.
2. the antidote of ccd image brightness according to claim 1, which is characterized in that left and right channel C CD image is obtained,
And after the step of described image is divided into band, further include：
Record the first luminance mean value of left and right channel C CD image.
3. the antidote of ccd image brightness according to claim 1, which is characterized in that make to described image block discrete remaining
String converts DCT, and the step of inhibiting to DCT high frequency coefficient is specially：
Discrete cosine transform is made to described image block, obtains the high frequency coefficient value of the first row；
Obtain the rejection coefficient from 0.5 linear increment to 1；
The high frequency coefficient value of the first row is multiplied with the rejection coefficient.
4. the antidote of ccd image brightness according to claim 2, which is characterized in that obtain left and right channel C CD image
Compensation coefficient, and the step of carrying out mean filter processing to two groups of compensation coefficients is specially：
By the second luminance mean value divided by the first luminance mean value, the compensation coefficient group of each band on left and right channel C CD image is obtained；
Mean filter is carried out to the compensation coefficient group.
5. a kind of correction system of ccd image brightness, which is characterized in that including：
Divide module, for obtaining left and right channel C CD image, and described image is divided into band；
Image block module, for by strips mosaic stitch centered on select the image block of default size；
DCT module for making discrete cosine transform to described image block, and inhibits DCT high frequency coefficient；
IDCT module, for making inverse discrete cosine transform IDCT to described image block；
Second logging modle, for recording the second luminance mean value of left and right channel C CD image；
Compensation coefficient module carries out mean value filter for obtaining the compensation coefficient of left and right channel C CD image, and to two groups of compensation coefficients
Wave processing；
Rectification module is obtained for the second luminance mean value of band or so channel C CD image to be multiplied with the compensation coefficient
Obtain final image.
6. the correction system of ccd image brightness according to claim 5, which is characterized in that further include：
First logging modle, for recording the first luminance mean value of left and right channel C CD image.
7. the correction system of ccd image brightness according to claim 5, which is characterized in that the DCT module includes：
DCT unit obtains the high frequency coefficient value of the first row for making discrete cosine transform to described image block；
Rejection coefficient unit, for obtaining the rejection coefficient from 0.5 linear increment to 1；
Inhibit unit, for the high frequency coefficient value of the first row to be multiplied with the rejection coefficient.
8. the correction system of ccd image brightness according to claim 6, which is characterized in that the compensation coefficient module includes：
Mean value is divided by unit, for the second luminance mean value divided by the first luminance mean value, to be obtained each item on left and right channel C CD image
The compensation coefficient group of band；
Filter unit, for carrying out mean filter to the compensation coefficient group.
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| CN101976429B (en) * | 2010-10-27 | 2012-11-14 | 南京大学 | Cruise image based imaging method of water-surface aerial view |
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| US8144218B2 (en) * | 2006-11-09 | 2012-03-27 | Olympus Corporation | Image signal processing apparatus, image signal processing program, and image signal processing method |
| CN101840570A (en) * | 2010-04-16 | 2010-09-22 | 广东工业大学 | Fast image splicing method |
| CN101968883A (en) * | 2010-10-28 | 2011-02-09 | 西北工业大学 | Method for fusing multi-focus images based on wavelet transform and neighborhood characteristics |
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