Strengthen PDP synthetic image method for quality with moving window
One, technical field
The present invention relates to the shown image of a kind of article on plasma display screen (PDP) and carry out the method that quality strengthens, particularly a kind of method of carrying out the enhancing of Real-time and Dynamic quality with the shown image of small size sliding window article on plasma display screen (PDP).
Two, background technology
The display quality that improves and improve the PDP image is one of the important goal of PDP product development and core technology.At present, developing multiple more effective algorithm aspect the improvement still picture display quality.Aspect the realtime graphic processing, mainly contain mean filter method and sharpening Enhancement Method.But there is following shortcoming in above-mentioned technology:
1) though effective to the method for still picture processing, but because computing method complexity, calculated amount are big, processing speed is slow, and certain limitation is arranged, and its treatment technology and being not suitable for directly applies to such as PDP and shows in the display technique of such dynamic real-time image.
2) common average noise reduction process and its effect mutual restriction of sharpening Enhancement Method all handled at image problem in a certain respect, if reach certain effect, implements more complicated, also needs to increase very big hardware cost.
3) when we when utilizing a kind of index of some Digital Image Processing algorithms to improve images, tend to cause other some distortions or loss.And the expression effect that always will improve the various aspects of image that we pursue just will be considered the synthetic image quality as much as possible.More satisfactory image processing algorithm should also will keep the original overall relativity of image when improving picture contrast, unlikelyly distortion or loss occur; Improve the details sense of image simultaneously, and the clutter that suppresses it, at the same time, also its dynamic false contour effect must be reduced to minimum.
Three, summary of the invention
The objective of the invention is to overcome the shortcoming of above-mentioned prior art, proposed a kind of with moving window enhancing PDP synthetic image method for quality, can be under the situation that keeps the image overall dynamic range, strengthen various scene details expressive abilities, reduce the dynamic false contours effect, improve the subjective viewing quality of image.
Basic foundation of the present invention is:
1), the histogram transformation in the little moving window is only relevant with the related local pixel content of this window, and can not be subjected to the influence of the Luminance Distribution situation of general image, thereby do not change the rule of the intensity profile of general image;
2), the brightness value of the pixel of processed window center position is adjusted by the statistics of the pixel intensity in the moving window, this adjustment is to carry out according to the rule that the trend that increases Luminance Distribution probability in the window strengthens its local contrast, thereby given prominence to detail contrast, emphasized the profile and the details of image.
3), because be to combine overall treatments such as enhancings, noise abatement, picture material is not caused the undue influence of being partial to certain aspect.
4), be processing to the processing of picture signal to monochrome information, thereby do not change the proportionate relationship between R, G, three kinds of primary colour signals of B.
Technical scheme of the present invention is:
Strengthen PDP synthetic image method for quality with moving window, at first the image that will show PDP calculates by pixel order, utilize then with processed pixel is the small size window of a slip at center, in window, processed pixel is carried out nonlinear histogram homogenizing, carry out noise reduction, details enhancing again and reduce false contouring.
The said image that will show PDP by the step that pixel order carries out statistical computation is: at first count the brightness value of all pixels in the window, then calculate their mean value, minimum value and maximal value.
The said step that processed pixel is carried out nonlinear histogram homogenizing is: brightness value, mean value, minimum value and the maximal value of all pixels in the window that is counted, calculate the new brightness value of processed pixel according to the conventional method of histogram homogenizing.
Said noise reduction step is by a two-dimensional digital low-pass filter that adapts to this processing window noise to be reduced processing.
It is by a two-dimensional digital Hi-pass filter that adapts to this processing window noise to be reduced processing that said details strengthens step.
More than said noise reduction and details strengthen step and when reality realizes, be merged in the window processor.When specific implementation, reach the coupling of noise reduction and details enhancing by comprehensive selection to low pass and Hi-pass filter parameter.
Said reduction false contouring is handled the additional effect that is actually window treatments of the present invention, and its meaning is: because the false contouring phenomenon is a kind of special effects that the PDP display produces owing to an employing principle, it produces when brightness value is in particular values.Through after the sliding window bi-level treatment that the present invention discussed, original brightness value is revised, upset producing the distribution of the special brightness value of false contouring to a great extent randomly, thereby alleviated the false contouring effect.
At in the past to the complex process method of the image data processing system of PDP, the present invention proposes the effectively comprehensive dynamic real-time sliding window treatment technology method that just can realize with simple circuit, can directly utilize the PDP frame data to store out device or multirow storer, only original FPGA program be carried out less modification or only increase less hardware equipment and obtain the effect of improving of picture quality.
Method of the present invention also can be used for the dynamic data of other display systems or view data is handled in real time, also can be used for still picture is carried out the various application places of comprehensive image quality improving.
1), can improve the synthetic image quality compare with method in the past, the present invention has following characteristics:; 2), the dynamic image that is applicable to PDP is handled; 3), realize that simply cost is low; 4), can use or be used in combination with other digital image processing method cascade.
Four, description of drawings
Fig. 1 is a theory diagram of the present invention.
Fig. 2 is the algorithm composition frame chart of the moving window processor (8) among Fig. 1.
Fig. 3 is the embodiment of the pixel distribution in a moving window.
Fig. 4 is the result who the image of Fig. 3 is handled with method of the present invention.
Fig. 5 carries out the effect that Flame Image Process is carried out analog computation with MATLAB software to this method, and wherein Fig. 5 (a) is an original image; Fig. 5 (b) is the image that sliding window is handled; Fig. 5 (c) be original image directly put figure; Fig. 5 (d) be sliding window handle directly put figure.
Fig. 6 is a kind of specific implementation method of moving window processor.
Description of drawings is as follows:
Referring to Fig. 1, the entire process system is inserted in the suitable link of picture signal.At first digital signal R (1), G (2), the B (3) with input converts brightness signal Y (5), red color difference signal PR (6) and blue difference signal PB (7) to by luminance transformation (4).Brightness signal Y (5) is admitted to moving window processor (8), enhancing after treatment brightness signal Y ' (9) send into brightness inverse transformation (14).Colour difference signal PR (6), PB (7) pass through delayed time system (10,11) respectively, colour difference signal PR ' (12) and PB ' (13) after the time-delay also are admitted to brightness inverse-transform matrix (14), after the processing through brightness inverse-transform matrix (14), digital signal R ' (15), G ' (16), B ' (17) digital signal after final output is handled.
Referring to Fig. 2, this is the formation block diagram of the moving window processor (8) among Fig. 1.The entire process device is made up of two-stage window treatments system.Wherein window pixel brightness value statistics sequencing unit (18), center pixel brightness value computing unit (19) and histogram constraint condition unit (21) have constituted first order window treatments, and promptly window histogram homogenizing is handled.Noise reduction/enhancing 2 dimension filtering integration algorithm unit (20) and noise reduction/enhancing constraint condition unit (22) have constituted second level window treatments, i.e. the noise reduction enhancement process.
At first brightness signal Y (5) is admitted to window pixel brightness value statistics sequencing unit (18), in this unit, the brightness value of each pixel in the window is added up the line ordering of going forward side by side; And calculate their maximal value, minimum value, mean value.Then the brightness data of window pixel and the data that calculate are all passed to center pixel brightness value computing unit (19).Simultaneously calculation constraint condition is also passed to center pixel brightness value computing unit (19) by histogram constraint condition unit (21).Center pixel brightness value computing unit (19) is finished the histogrammic calculating in the window, thereby calculates the brightness value after the processing of center pixel.So just having finished the histogram homogenizing handles.
Handled window data (23) by the first order after the processing of histogram homogenizing and be sent to noise reduction/enhancing two-dimensional filtering integration algorithm unit (20).Simultaneously calculation constraint condition is also passed to noise reduction/enhancing two-dimensional filtering integration algorithm unit (20) by noise reduction/enhancing constraint condition unit (22).The processing of the noise reduction/enhancing two-dimensional filtering integration algorithm in the window is finished in noise reduction/enhancing two-dimensional filtering integration algorithm unit (20), obtains the new brightness value of the center pixel after handle the second level.So just finished the noise reduction enhancement process.
Fig. 3 is two concrete instances of the pixel distribution in a moving window, the numeral among the figure be the original brightness value of this position pixel.Fig. 3 a) in, the upper left quarter pixel brightness value is big, and the brightness value of right lower quadrant pixel is little.Present the variation of deepening gradually by the upper left corner to the lower right corner.At Fig. 3 b) in, the top pixels brightness value is big, and the brightness value of bottom pixel is little.Present the variation of deepening gradually from top to bottom.
Fig. 4 a), Fig. 4 b) be respectively with moving window disposal route of the present invention to Fig. 3 a), 3b) two kinds of results that image carries out computing.The dynamic range of two kinds of images has all obtained expansion in various degree, and has increased the difference of image border details, thereby has improved the detail contrast in the small size scope.The mean flow rate of image does not have big variation in the window, thereby the brightness of general image is not caused distortion.
Referring to Fig. 5, be this method to be carried out the effect that Flame Image Process is carried out analog computation with MATLAB software, wherein Fig. 5 is an original image a), Fig. 5 b) be Fig. 5 statistic histogram a).Fig. 5 c) be the result of sliding window overall treatment, Fig. 5 d) be Fig. 5 c) statistic histogram.As can be seen, the image after the processing has apparent in view improvement aspect details, and at darker position, its gray-level has obtained expansion, and this can obviously find out on its histogram.And with regard to full figure, its dynamic range does not have very big difference.
Referring to Fig. 6, be the circuit block diagram of a kind of specific implementation method of moving window processor.The entire process system realizes during by a FPGA.Digital signal R (1), G (2), the B (3) of input convert brightness signal Y (5), red color difference signal PR (6) and blue difference signal PB (7) to by luminance transformation (4).Brightness signal Y (5) is admitted to picture element caching (28), 1H buffer memory (29) and 1H buffer memory (30) and forms moving window storage array data.These data are admitted to after window pixel intensity statistical circuit (31) carries out statistical computation, are fed to window treatments 1 (32) and carry out the calculating that the center pixel histogram is handled, and finish first order window treatments.Data after processed are admitted to window treatments 2 (33) and carry out the calculating of noise reduction enhancement process, finish second level window treatments, and produce the new brightness signal Y after all finishing dealing with ' (11).
Send control information for window treatments 1 (32) and window treatments 2 (33) by prewired circuit (42) by preset threshold value (34) and preset threshold value (35), to make necessary condition restriction to handling to calculate.
The clock signal clk (24), synchronizing signal H (25) and the V (26) that are come by system are sent to the needed address signal of address production electric circuit (27) the whole window processor of generation, and this address signal is sent in each delay circuit simultaneously.
Two kinds of colour difference signal Pr (6), Pb (7) are respectively by producing colour difference signal Pr ' (12) and Pb ' (13) after the coupling by 1H buffer memory (36), 1H buffer memory (37), time-delay buffer memory (38) with by the time match circuit that 1H buffer memory (39), 1H buffer memory (40), time-delay buffer memory (41) constitute.
Brightness signal Y after the processing ' (11), colour difference signal Pr ' (12) and Pb ' (13) produce output signal R ' (15), G ' (16), B ' (17) through brightness inverse transformation (14).
The advantage of the invention and good effect
1) real time enhancing that is applicable to the dynamic image of PDP is processed;
2) be applicable to natural image, the image object of processing does not require the differentiation content type; Keep the original key property of image, carry out the self adaptation multi-objective, be used for improving the comprehensive quality of image;
3), owing to adopted the multiple integrated treatment of secondary window, can improve to a certain extent the false contouring effect that PDP shows image;
4), can be on the basis of available circuit and software only increase additional process software or hardware and can realize, realize simpler;
Data image signal display system and the application facet that 5), also can be used for any other.
6), can use or be used in combination with other digital image processing method cascade, to reach more effect.