CN103024328A - Method for improving screenshot quality of digital video recorder - Google Patents

Abstract

The invention discloses a method for improving image screenshot quality of a digital video recorder without adding hardware cost. The method is better applied to monitoring service and applies a weight-based luminance and gray level block linear expansion image enhancement algorithm into a DVR (digital video recorder) screenshot processing method. Before a screenshot file is generated, the weight-based luminance and gray level block linear expansion image enhancement algorithm is used for image enhancement operation for original image data so as to improve image quality, and then the image data subjected to image enhancement operation are stored to an image file. The DVR screenshot processing method includes: acquiring the original image data; making statistics on image luminance and gray level extreme values; judging by inputting image luminance and gray level threshold values; inputting image luminance and gray level blocks; inputting image block luminance and gray level statistics; outputting image luminance and gray level blocks; performing weight-based luminance and gray level block linear expansion; and storing processed image data.

Description

A kind of method that improves digital video recorder grabgraf quality

Technical field

The invention belongs to the technical field of video monitoring, be specifically related to a kind of method that improves digital video recorder grabgraf quality.

Background technology

DVR (Digital Video Recorder), it is digital video recorder, it is the computer system that a cover can compress to the voice data video data stores processor, have voice messaging and image information are recorded for a long time, recorded a video, the functions such as retrieval video and audio recording information, grabgraf, telemonitoring and control ancillary equipment.

DSP (Digital Signal Processor), namely digital signal processor is a core devices among the DVR.This device is responsible for finishing the catching of audio-video signal in the DVR equipment, the compressed encoding of audio-video signal, the functions such as decoding of audio-video signal.

The grabgraf functional module is the necessary functions module of DVR equipment, the function of grabgraf module is realized by DSP, the specific implementation process is, DSP receives image grabbing command, DSP is according to the image of image grabbing command crawl expection, DSP sends the image data that grabs to the DVR master controller, and the DVR master controller saves as the picture that computer can be identified with the pictorial information of receiving.

The general operation method of grabgraf module is among the DVR: the DVR master controller sends image grabbing command, DSP receives the original video data of catching the yuv format of current time after the image grabbing command that master controller sends, and conversion is stored as the bmp form or processes through compression algorithm and is stored as the jpg form DSP through color space with yuv format.

When partially bright, partially dark, the vaporific situation such as fuzzy appearred in the content in the video scene that needs grabgraf, the effect of grabgraf was just not ideal, and the user is difficult to get access to the valuable information in the video, does not reach the grabgraf effect of expection.

Summary of the invention

Technology of the present invention is dealt with problems and is: overcome the deficiencies in the prior art, provide a kind of can be in the situation that do not increase hardware cost and improve the grabgraf quality of image, be applied to the method for the raising digital video recorder grabgraf quality of monitor service better.

Technical solution of the present invention is: the method for this raising digital video recorder grabgraf quality, a kind of brightness/gray scale subregion linear expansion algorithm for image enhancement based on weight is applied in the digital video recorder DVR grabgraf processing method, before generating the grabgraf file, by a kind of brightness/gray scale subregion linear expansion algorithm for image enhancement based on weight raw image data is carried out the image enhance operation to improve picture quality, again the view data behind the image enhance operation is stored as image file afterwards;

Wherein digital video recorder DVR grabgraf processing method may further comprise the steps:

(1) obtains raw image data;

(2) brightness/gray scale statistics of extremes;

(3) the input image lightness gray threshold is judged;

(4) input image lightness gray scale subregion;

(5) input picture subregion brightness/gray scale statistics;

(6) output image brightness/gray scale subregion;

(7) based on the brightness/gray scale subregion linear expansion of weight;

(8) view data after the stores processor.

This method is applied on the DVR equipment, can solve the undesirable problem of grabgraf effect when occurring partially bright, partially dark, the vaporific situation such as fuzzy in the video scene that needs grabgraf, in the situation that do not increase hardware cost, can obtain better picture quality effect, improve the grabgraf quality of image.

Description of drawings

Fig. 1 is the general processing method sketch of grabgraf in the DVR equipment;

Fig. 2 is the processing method sketch of grabgraf after DVR equipment application the inventive method;

Fig. 3 is the detail flowchart of the processing method of grabgraf after DVR equipment application the inventive method.

Embodiment

The method of this raising digital video recorder grabgraf quality, a kind of brightness/gray scale subregion linear expansion algorithm for image enhancement based on weight is applied in the digital video recorder DVR grabgraf processing method, before generating the grabgraf file, by a kind of brightness/gray scale subregion linear expansion algorithm for image enhancement based on weight raw image data is carried out the image enhance operation to improve picture quality, again the view data behind the image enhance operation is stored as image file afterwards;

Wherein digital video recorder DVR grabgraf processing method may further comprise the steps:

(1) obtains raw image data;

(2) brightness/gray scale statistics of extremes;

(3) the input image lightness gray threshold is judged;

(4) input image lightness gray scale subregion;

(5) input picture subregion brightness/gray scale statistics;

(6) output image brightness/gray scale subregion;

(7) based on the brightness/gray scale subregion linear expansion of weight;

(8) view data after the stores processor.

This method is applied on the DVR equipment, can solve the undesirable problem of grabgraf effect when occurring partially bright, partially dark, the vaporific situation such as fuzzy in the video scene that needs grabgraf, in the situation that do not increase hardware cost, can obtain better picture quality effect, improve the grabgraf quality of image.

Preferably, in the step (1): raw image data adopts yuv format.

Preferably, in the step (2): the distribution of the brightness/gray scale of all pixels of original image is added up, draw minimum value and the maximum of original image brightness/gray scale, namely travel through the brightness/gray scale of original image and relatively big or small, obtain brightness/gray scale minimum value nYPixelMin and the brightness/gray scale maximum nYPixelMax of original image.

Preferably, in the step (3): according to brightness/gray scale minimum value nYPixelMin and brightness/gray scale maximum nYPixelMax, and default original image needs brightness/gray scale minimum threshold nYUserMin to be processed and brightness/gray scale max-thresholds nYUserMax, definite needs carry out the brightness/gray scale interval (nYSrcMin, nYSrcMax) of regional linear expansion.

Preferably, in the step (4): will be in the interval (nYSrcMin of the brightness/gray scale that to carry out linear expansion, nYSrcMax) gray value in is divided into the identical nBlock of length interval, and the value of nBlock is set by the user, the starting point nYSrcGray of each original image brightness/gray scale subregion _{I, 0}Expression, the terminal point nYSrcGray of each original image brightness/gray scale subregion _I.1Expression.

Preferably, in the step (5): in the brightness/gray scale subregion section that determines, the number of pixels that respectively brightness/gray scale is distributed in each section adds up, and corresponding each brightness/gray scale subregion obtains respectively being distributed in the number of pixels nYSrcBlockPixel in this brightness/gray scale subregion _iWith all nYSrcBlockPixel _iAddition obtains being distributed in the pixel count sum nYSrcBlockPixelTotal in all brightness/gray scale subregions.

Preferably, in the step (6): the gray value that will be in the target image brightness/gray scale interval (nYDstMin, nYDstMax) is divided into the different nBlock of length interval, each length of an interval degree YDstBlockLength _iBy weights W _iWith the acquisition of multiplying each other of output image brightness/gray scale total length, weights W _iBy the number of pixels nYSrcBlockPixel in each subregion in the input picture _iObtain the starting point nYDstGray of each target image brightness/gray scale subregion divided by the sum of all pixels nYSrcBlockPixelTotal that is distributed in all brightness/gray scale subregions of input picture _{I, 0}Represent the terminal point nYDstGray of each target image brightness/gray scale subregion _I.1Represent.

Preferably, in the step (7): between input image lightness gray scale subregion and output image brightness subregion, set up mapping relations, that is, at first calculate the mapping ratio α of each brightness/gray scale subregion according to formula (1) _i

${\mathrm{\α}}_i=\frac{{\mathrm{nYDstGray}}_{i,1}-n{\mathrm{YDstGray}}_{i,0}}{{\mathrm{nYSrcGray}}_{i,1}-{\mathrm{nYSrcGray}}_{i,0}}---\left(1\right)$

Then, for needing brightness/gray scale value to be processed to shine upon output in the original image, for not needing brightness/gray scale value to be processed directly to export in the original image.

Preferably, in the step (8): conversion is stored as the bmp form or is stored as the jpg form through overcompression the view data of the yuv format after will processing through color space.

Describe with regard to a preferred embodiment of the present invention now.

The general process flow of grabgraf as shown in Figure 1 in the DVR equipment.General processing method comprises that raw image data obtains with view data and stores.After getting access to the raw image data of monitoring scene by the DSP module in the DVR equipment, data storages is according to the setting of system, the raw image data of the yuv format that gets access to is stored as the target image that is stored as the jpg form after the target image of bmp form or the compressed algorithm process after color space is changed.

Fig. 2 is the process flow sketch of grabgraf after DVR equipment application the inventive method.The present invention is applied to the figure image intensifying in the grabgraf of DVR equipment, can Effective Raise the picture quality of grabgraf picture, can effectively solve when occurring partially bright, partially dark, the vaporific undesirable problem of grabgraf effect when the situation such as bluring in the video scene that needs grabgraf.

Fig. 3 is the processing method detail flowchart that DVR equipment is used grabgraf after the inventive method, referring to Fig. 3, the application's embodiment is introduced, and may further comprise the steps:

⑴ arrive the raw image data of yuv format by the image data acquisition of DSP.

⑵ add up the distribution of the brightness/gray scale of whole original image, draws minimum value and the maximum of image brightness gray scale, and concrete grammar is:

The brightness/gray scale original maximum nYPixelMax of the pixel of image is set to 0 respectively, and the original intensity minimum gray value nYPixelMin of image pixel is set to 255.Afterwards entire image is traveled through, obtain the brightness/gray scale value nYVal of each pixel.If the brightness/gray scale value nYVal of pixel is greater than nYPixelMax, the brightness/gray scale value nYVal assignment that then will put is to nYPixelMax, if the brightness/gray scale value nYVal of pixel is less than or equal to nYPixelMax, then the value of nYPixelMax remains unchanged; If the brightness/gray scale value nYVal assignment that the brightness/gray scale value nYVal of pixel less than nYPixelMin, then will put is to nYPixelMin, if the brightness/gray scale value of pixel is greater than or equal to nYPixelMin, then the value of nYPixelMin remains unchanged.

After having traveled through this width of cloth image, can obtain brightness/gray scale minimum value nYPixelMin and the brightness/gray scale maximum nYPixelMax of entire image.

⑶ determine to carry out the original image brightness/gray scale interval of brightness/gray scale linear expansion.After calculating original image brightness/gray scale extreme value (brightness/gray scale minimum value nYPixelMin and brightness/gray scale maximum nYPixelMax), the original image of setting in conjunction with the user needs brightness/gray scale threshold value extreme value to be processed (brightness/gray scale minimum threshold nYUserMin and brightness/gray scale max-thresholds nYUserMax), definite needs carry out the brightness/gray scale interval (nYSrcMin, nYSrcMax) of regional linear expansion.In a kind of preferred scheme, it is (15,240) that the original image that the user sets needs brightness/gray scale threshold value extreme value to be processed interval.Concrete grammar is:

$\mathrm{nYSrcMin}=\left\{\begin{array}{cc}\mathrm{nYPixelMin}& (\mathrm{nYPixelMin}>\mathrm{nYUserMin})\\ \mathrm{nYUserMin}& (\mathrm{nYPixelMin}<\mathrm{nYUserMIn})\end{array}\right.$

$\mathrm{nYSrcMax}=\left\{\begin{array}{cc}\mathrm{nYPixelMax}& (\mathrm{nYPixelMax}<\mathrm{nYUserMax})\\ \mathrm{nYUserMax}& (\mathrm{nYpixelMax}>\mathrm{nYUserMax})\end{array}\right.$

⑷ be divided into nBlock interval to the interior gray value of brightness/gray scale interval (nYSrcMin, nYSrcMax) that needs carry out linear expansion, and the value of nBlock is set by the user, and in a kind of preferred scheme, the value of nBlock is 8.Concrete grammar is:

Calculate the input picture partition length:

YSrcBlockLength=(nYSrcMax-nYSrcMin)/nBlock

The starting point nYSrcGray of first brightness/gray scale subregion _1,0With terminal point nYSrcGray _1.1Be shown below:

$\left\{\begin{array}{c}{\mathrm{nYSrcGray}}_{\mathrm{1,0}}=\mathrm{nYSrcMin}\\ {\mathrm{nYSrcGray}}_{\mathrm{1,1}}=\mathrm{nYSrcMin}+\mathrm{YSrcBlockLength}\end{array}\right.$

The starting point nYSrcGray of i brightness/gray scale subregion _{I, 0}With terminal point nYSrcGray _I.1Be shown below:

$\left\{\begin{array}{cc}{\mathrm{nYSrcGray}}_{i,0}={\mathrm{nYSrcGray}}_{i-\mathrm{1,1}}& (1<i<\mathrm{nBlock})\\ {\mathrm{nYSrcGray}}_{\mathrm{1,1}}={\mathrm{nYSrcGray}}_{i,0}+\mathrm{YSrcBlockLength}& (1<i<\mathrm{nBlock})\end{array}\right.$

The place nYSrcGray of nBlock brightness/gray scale subregion _{NBlock, 0}With terminal point nYSrcGray _NBlock.1Be shown below:

$\left\{\begin{array}{c}{\mathrm{nYSrcGray}}_{\mathrm{nBlock},0}={\mathrm{nYSrcGray}}_{\mathrm{nBlock}-1,1}\\ {\mathrm{nYSrcGray}}_{\mathrm{nBlock},1}=\mathrm{nYSrcMax}\end{array}\right.$

⑸ add up to the number of pixels in each brightness/gray scale section respectively, obtains respectively being distributed in the number of pixels nYSrcBlockPixel in each brightness/gray scale subregion _i, with all nYSrcBlockPixel _iAddition obtains being distributed in the pixel count sum nYSrcBlockPixelTotal in all brightness/gray scale subregions, and concrete grammar is:

$\mathrm{nYSrcBlockPixelTotal}=\underset{i=1}{\overset{\mathrm{nBlock}}{\mathrm{\&Sigma;}}}{\mathrm{nYSrcBlockPixel}}_i$

⑹ be divided into the different nBlock of length interval to the gray value that is in the target image brightness/gray scale interval (nYDstMin, nYDstMax).In a kind of preferred scheme, the value of nBlock is 8, is (0,220) between the object brightness gray area.The length YDstBlockLength of each subregion _iBy weights W _iWith the acquisition of multiplying each other of output image brightness/gray scale total length.Concrete grammar is:

YDstBlockLength _i=W _i×(nYDstMax-nYDstMin)

Weights W _iBy the number of pixels nYSrcBlockPixel in each subregion in the input picture _iObtain divided by the sum of all pixels nYSrcBlockPixelTotal that is distributed in all brightness/gray scale subregions of input picture, circular is shown below:

$W_i=\frac{\mathrm{nYSrcBlock}{\mathrm{Pixel}}_i}{\mathrm{nYSrcBlockPixelTotal}}$

The starting point nYDstGray of first brightness/gray scale subregion _1,0With terminal point nYDstGray _1.1Be shown below:

$\left\{\begin{array}{c}{\mathrm{nYDstGray}}_{\mathrm{1,0}}=\mathrm{nYDstMin}\\ {\mathrm{nYDstGray}}_{\mathrm{1,1}}=\mathrm{nYSrcMin}+{\mathrm{YDStBlockLength}}_1\end{array}\right.$

The starting point nYDstGray of i brightness/gray scale subregion _{I, 0}With terminal point nYDstGray _I.1Be shown below:

$\left\{\begin{array}{cc}{\mathrm{nYDstGray}}_{i,0}={\mathrm{nYDstGray}}_{i-\mathrm{1,1}}& (1<i<\mathrm{nBlock})\\ {\mathrm{nYDstGray}}_{\mathrm{1,1}}={\mathrm{nYDstGray}}_{i,0}+{\mathrm{YDstBlockLength}}_i& (1<i<\mathrm{nBlock})\end{array}\right.$

The place nYDstGrat of nBlock brightness/gray scale subregion _{NBlock, 0}With terminal point nYDstGray _NBlock.1Be shown below:

$\left\{\begin{array}{c}{\mathrm{nYDstGray}}_{\mathrm{nBlock},0}={\mathrm{nYDstGray}}_{\mathrm{nBlock}-1,1}\\ {\mathrm{nYDstGray}}_{\mathrm{nBlock},1}=\mathrm{nYDstMax}\end{array}\right.$

⑺ set up mapping relations between input image lightness gray scale subregion and output image brightness subregion.Calculate first the mapping ratio α of each brightness/gray scale subregion _i:

${\mathrm{\&alpha;}}_i=\frac{{\mathrm{nYDstGray}}_{i,1}-{\mathrm{nYDstGray}}_{i,0}}{{\mathrm{nYSrcGray}}_{i,1}-{\mathrm{nYSrcGray}}_{i,0}}$

Be in the brightness/gray scale value nYSrc of the pixel in (nYSrcMin, nYSrcMax) zone for brightness/gray scale value in the original image _k, at first judge nYSrc _kBe in which subregion of input image lightness gray scale subregion, suppose through after judging gray value nYSrc _kBe in i the brightness/gray scale subregion, then be handled as follows:

nYDst _k=nYDstGray _i,0+α _i×(nYSrc _k-nYDstGray _i,0)

Be in the brightness/gray scale value nYSrc of (nYSrcMin, nYSrcMax) extra-regional pixel for brightness/gray scale value in the original image _m, then do not process, directly export.

nYDst _m=nYSrc _m

⑻ the view data that incite somebody to action yuv format after treatment is stored as the bmp form or is stored as the jpg form through overcompression through color space conversion.

The above; it only is preferred embodiment of the present invention; be not that the present invention is done any pro forma restriction, any simple modification, equivalent variations and modification that every foundation technical spirit of the present invention is done above embodiment all still belong to the protection range of technical solution of the present invention.

Claims (9)

1. method that improves digital video recorder grabgraf quality, it is characterized in that, a kind of brightness/gray scale subregion linear expansion algorithm for image enhancement based on weight is applied in the digital video recorder DVR grabgraf processing method, before generating the grabgraf file, by a kind of brightness/gray scale subregion linear expansion algorithm for image enhancement based on weight raw image data is carried out the image enhance operation to improve picture quality, again the view data behind the image enhance operation is stored as image file afterwards;

Wherein digital video recorder DVR grabgraf processing method may further comprise the steps:

(1) obtains raw image data;

(2) brightness/gray scale statistics of extremes;

(3) the input image lightness gray threshold is judged;

(4) input image lightness gray scale subregion;

(5) input picture subregion brightness/gray scale statistics;

(6) output image brightness/gray scale subregion;

(7) based on the brightness/gray scale subregion linear expansion of weight;

(8) view data after the stores processor.

2. the method for raising digital video recorder grabgraf quality according to claim 1 is characterized in that, in the step (1): raw image data adopts yuv format.

3. the method for raising digital video recorder grabgraf quality according to claim 2, it is characterized in that, in the step (2): the distribution of the brightness/gray scale of all pixels of original image is added up, draw minimum value and the maximum of original image brightness/gray scale, namely travel through the brightness/gray scale of original image and relatively big or small, obtain brightness/gray scale minimum value nYPixelMin and the brightness/gray scale maximum nYPixelMax of original image.

4. the method for raising digital video recorder grabgraf quality according to claim 3, it is characterized in that, in the step (3): according to brightness/gray scale minimum value nYPixelMin and brightness/gray scale maximum nYPixelMax, and default original image needs brightness/gray scale minimum threshold nYUserMin to be processed and brightness/gray scale max-thresholds nYUserMax, definite needs carry out the brightness/gray scale interval (nYSrcMin, nYSrcMax) of regional linear expansion.

5. the method for raising digital video recorder grabgraf quality according to claim 4, it is characterized in that, in the step (4): will be in the interval (nYSrcMin of the brightness/gray scale that to carry out linear expansion, nYSrcMax) gray value in is divided into the identical nBlock of length interval, the value of nBlock is set by the user, the starting point nYSrcGray of each original image brightness/gray scale subregion _{I, 0}Expression, the terminal point nYSrcGray of each original image brightness/gray scale subregion _I.1Expression.

6. the method for raising digital video recorder grabgraf quality according to claim 5, it is characterized in that, in the step (5): in the brightness/gray scale subregion section that determines, the number of pixels that respectively brightness/gray scale is distributed in each section adds up, corresponding each brightness/gray scale subregion obtains respectively being distributed in the number of pixels nYSrcBlockPixel in this brightness/gray scale subregion _iWith all nYSrcBlockPixel _iAddition obtains being distributed in the pixel count sum nYSrcBlockPixelTotal in all brightness/gray scale subregions.

7. the method for raising digital video recorder grabgraf quality according to claim 6, it is characterized in that, in the step (6): will be in the interval (nYDstMin of target image brightness/gray scale, nYDstMax) gray value in is divided into the different nBlock of length interval, each length of an interval degree YDstBlockLength _iBy weights W _iWith the acquisition of multiplying each other of output image brightness/gray scale total length, weights W _iBy the number of pixels nYSrcBlockPixel in each subregion in the input picture _iObtain the starting point nYDstGray of each target image brightness/gray scale subregion divided by the sum of all pixels nYSrcBlockPixelTotal that is distributed in all brightness/gray scale subregions of input picture _{I, 0}Represent the terminal point nYDstGray of each target image brightness/gray scale subregion _I.1Represent.

8. the method for raising digital video recorder grabgraf quality according to claim 7, it is characterized in that, in the step (7): between input image lightness gray scale subregion and output image brightness subregion, set up mapping relations, that is, at first calculate the mapping ratio α of each brightness/gray scale subregion according to formula (1) _i

${\mathrm{\&alpha;}}_i=\frac{{\mathrm{nYDstGray}}_{i,1}-{\mathrm{nYDstGray}}_{i,0}}{{\mathrm{nYSrcGray}}_{i,1}-{\mathrm{nYSrcGray}}_{i,0}}---\left(1\right)$

Then, for needing brightness/gray scale value to be processed to shine upon output in the original image, for not needing brightness/gray scale value to be processed directly to export in the original image.

9. the method for raising digital video recorder grabgraf quality according to claim 8, it is characterized in that, in the step (8): conversion is stored as the bmp form or is stored as the jpg form through overcompression the view data of the yuv format after will processing through color space.

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