CN101924949B - Image processing method and image processing system - Google Patents

Abstract

The invention discloses an image processing method and an image processing system, which are suitable for processing image information, wherein the image information comprises a plurality of processing pixels. The image processing method comprises the following steps: a) setting a group of parameters; b) establishing a brightness comparison table; c) establishing a chroma brightness comparison table; d) reading the image information; e) judging the image format of the image information; f) if the image format is the first format, generating an adjusted chroma value and a first adjusted brightness value corresponding to one of the processing pixels by using a chroma brightness comparison table; and g) if the image format is the second format, generating an adjusted chrominance value, a first adjusted luminance value and a second adjusted luminance value corresponding to one of the plurality of processing pixels by using the chrominance luminance comparison table and the luminance comparison table.

Description

Image processing method and image processing system

technical field

The present invention relates to an image processing method and an image processing system, and in particular to an image processing method and an image processing system completed by using a look-up table.

Background technique

With the continuous advancement of various digital image display technologies, various high-quality, high-stability, and multi-functional electronic display devices have been popularized in the daily life of the general public, such as LCD screens, plasma displays, projectors, etc. Various digital electronic display devices have already become the main display media for various daily information or interpersonal communication of the people.

The main factors that affect the image display quality include the brightness contrast (contraction) and color saturation (saturation) of the image itself. Generally speaking, the contrast of an image refers to the brightness ratio between the bright area and the dark area in the image. Appropriate contrast enhancement is more comfortable for human vision. The color saturation is determined by the chrominance of various colors.

Some of the traditional image contrast and color enhancement technologies are performed in the color space of the three primary colors of red, green and blue (RGB). However, most of the video or video streaming video formats used in the industry today do not use the RGB color space, but use the brightness and color separation (Y/C) color space to store information or transmit, that is, the YCbCr video format . That is to say, the traditional method may need to convert the image or video stream in YCbCr format to RGB format before performing image processing such as contrast or color enhancement on the image or video stream in RGB format. Even after image processing, a reverse conversion step (RGB to YCbCr) is required to convert the processed information back into the format used by the system. As a result, the additional color space conversion will cause a computing burden on the system, and real-time computing on the video stream cannot be achieved.

On the other hand, in the current image contrast and color enhancement technology for the YCbCr format, because the YCbCr format has a luminance component (Y) and two chroma components (Cb, Cr). The image processor can establish a brightness comparison table to adjust the brightness component (Y) according to the requirement of image contrast, and establish one or two sets of saturation comparison tables to adjust the two saturation components (Cb, Cr) according to the requirement of color enhancement. However, in each image processing process, each component (Y, Cb, Cr) of the image information must be calculated and adjusted sequentially using the brightness comparison table or chroma comparison table, that is, three components need to be calculated three times. For the calculation process, heavy calculation requirements will cause an excessive burden on the system processor for an electronic system without an independent image processor.

In order to solve the above problems, the present invention proposes an image processing method and an image processing system to solve the above problems.

Contents of the invention

An object of the present invention is to provide an image processing method suitable for processing an image information including a plurality of processing pixels.

According to a specific embodiment, the image processing method includes the following steps: a) setting a group of parameters; b) establishing a brightness comparison table according to the group of parameters; c) establishing a color brightness comparison table according to the group of parameters and the brightness comparison table Table; d) read the image information; e) judge an image format of the image information; f) if the image format is the first format (for example: YCbCr 4: 2: 2), use the chroma brightness comparison table, generating an adjusted chroma value and a first adjusted luminance value corresponding to one of the plurality of processed pixels; and g) if the image format is a second format (for example: YCbCr 4:2:0), using the color The luminance comparison table and the luminance comparison table generate an adjusted chroma value, a first adjusted luminance value, and a second adjusted luminance value corresponding to one of the processing pixels.

Another object of the present invention is to provide an image processing system, which includes a storage module, a computing module and a processing module. The computing module and the processing module are respectively electrically connected to the storage module.

According to a specific embodiment, the storage module stores image information, and the image information includes a plurality of processing pixels. The calculation module establishes a brightness comparison table according to a set of parameters, and then according to the set of parameters and the brightness comparison table, the calculation module establishes a saturation brightness comparison table, and stores the brightness comparison table and the saturation brightness comparison table in the storage module.

The processing module reads the image information from the storage module and judges the image format of the image information. If the image format is the first format, the processing module uses the chroma brightness comparison table stored in the storage module to generate the adjusted chroma value and the second format. The adjusted brightness value corresponds to one of the plurality of processed pixels. If the image format is the second format, the processing module utilizes the saturation brightness comparison table and the brightness comparison table stored in the storage module to generate an adjusted saturation value, a first adjusted brightness value and a second adjusted brightness value The brightness value corresponds to one of the processing pixels.

That is to say, the image processing method and image processing system of the present invention can adjust a brightness value and a saturation value with one calculation process by setting up a brightness-saturation comparison table, thereby simplifying the operation flow and processing of the image processing time. The advantages and spirit of the present invention can be further understood through the following detailed description of the invention and the accompanying drawings.

Description of drawings

FIG. 1 is a flowchart of an image processing method according to a specific embodiment of the present invention.

FIG. 2 is a functional block diagram of an image processing system capable of implementing the image processing method of the present invention.

Detailed ways

Please refer to FIG. 1 and FIG. 2 . FIG. 1 is a flow chart of an image processing method according to a specific embodiment of the present invention. FIG. 2 is a functional block diagram of an image processing system 1 capable of implementing the image processing method of the present invention. The image processing method and the image processing system of the present invention are suitable for processing an image information (such as an image, a multimedia video or a video stream), and the image information has an image format. As shown in FIG. 2 , the image processing system 1 in this embodiment includes a storage module 10 , a calculation module 12 , a processing module 14 and an input module 16 . The computing module 12 and the processing module 14 are respectively electrically connected to the storage module 10 . The input module 16 is electrically connected to the computing module 12 . The storage module 10 stores image information, and the image information includes a plurality of processing pixels.

In this embodiment, the image processing method and the image processing system 1 of the present invention can process different image formats correspondingly. In practical applications, the current common image formats can be classified into YCbCr 4:4:4 (representing that it uses the YCbCr color space format and the YCbCr sampling ratio is 4:4:4 full sampling), YCbCr 4:2:2 (representing that it Adopt YCbCr color space format and YCbCr sampling ratio is 4:2:2 partial sampling) or YCbCr4:2:0 (YCbCr color space format and YCbCr sampling ratio is 4:2:0 or 4:1:1 partial sampling), etc. Various classifications.

For example, the commonly used YCbCr 4:2:2 image formats in the industry include YUY2, UYVY, YUV2 and other formats, and the commonly used YCbCr 4:2:0 image formats include YV12, NV12 and I420 formats used by DVD discs.

In image information, the smallest unit image is a pixel (picture element, pixel), and at the beginning of YCbCr4:4:4 (full sampling), each pixel has complete three component information (Y, Cb, Cr) . In order to meet the current compression or image processing requirements, under the YCbCr 4:2:2 or YCbCr 4:2:0 architecture, multiple adjacent pixels can be defined as a macro-pixel. The definition of a macro pixel depends on different formats, for example, it can be 2 adjacent pixels or 2×2 adjacent pixel blocks.

Generally speaking, in YCbCr 4:2:2, the Y component (Y1) of the first pixel, the Cb component (Cb1) of the first pixel, the Y component (Y2) of the second pixel and the Composed of Cr components (Cr2) of two pixels, that is, in each macro pixel of YCbCr 4:2:2, the ratio of brightness value and saturation value is 1:1 (two brightness values and two saturation values). In practical applications, for the convenience of calculation and processing, in the YCbCr 4:2:2 format, a macro pixel [Y1, Cb1, Y2, Cr2] is usually divided into two processing pixels, which are the processing pixels [Y1 , Cb1] and another processed pixel [Y2, Cr2]. In this embodiment, the processing module performs image adjustment processing with a processing pixel as a basic unit.

On the other hand, in YCbCr 4:2:0, a macro pixel can be composed of Y components (Y1, Y2, Y3, Y4) of four different pixels, a Cb component (Cb), and a component (Cr) (So the sampling ratio of YCbCr 4:2:0 format can also be called 4:1:1), that is, in each macro pixel of YCbCr 4:2:0, the brightness value and chroma value are 2:1 Scale (four luma values and two chroma values). In practical applications, for the convenience of calculation and processing, in the YCbCr 4:2:0 format, a macro pixel [Y1, Y2, Y3, Y4, Cb, Cr] is usually divided into two processing pixels, here In an embodiment, they may be the processing pixel [Y1, Y2, Cb] and another processing pixel [Y3, Y4, Cr].

As shown in Figures 1 and 2, the present invention first executes step S100 to set a group of parameters. In this embodiment, the setting of the parameters can be generated by the calculation module 12, or input by the user through the input module 16 and sent to the computing module 12, but not limited thereto. In this embodiment, the set of parameters may be (St, Sa), where St∈[0,1], Sa≧0. The setting of the group of parameters can be determined according to the actual application requirements, and can be adjusted according to the quality of the final image processing result.

Subsequently, step S102 is executed, and the calculation module 12 generates a brightness comparison table according to the set of parameters. In this embodiment, the calculation module 12 can also store the brightness comparison table in the storage module 10 . In this embodiment, the brightness value of the image information of the present invention can be stored in 8 bits and divided into 256 levels (the brightness value can be distributed between 0-255). In this embodiment, the brightness comparison table can be generated according to the following formula:

$\mathrm{Yout}\left(x\right)=\mathrm{Bound}{[f_Y(\mathrm{St.},f\left(x\right))x-b_Y(\mathrm{St.},f\left(x\right))]}_{\min }^{\max },$ Where x is an integer between 0 and 255, f _Y (St, f(x))=St×f(x)+(1-St), b _Y (St, f(x))=16×St× (f(x)-1), f(x) is a nonlinear function used to generate a gain relative to the input signal, for example f(x)=[255(x/255) ^r +1]/( x+1), r>0, the equation f(x) used for adjustment can be determined according to the actual application situation. where the Bound function is defined as $B=\mathrm{Bound}{\left[A\right]}_{\min }^{\max },$ When min≤A≤max, B=A; when A≤min, B=min; when max≤A, B=A. Wherein 0≤min<max, in this embodiment, the value of max can be 255 or 235, and the value of min can be 0 or 16.

In this embodiment, the format of the brightness comparison table can be shown in Table 1 below:

Enter the brightness value output brightness value 0 Yout[0]

1 Yout[1] ... ... 255 Yout[255]

Table I

Then step S104 is executed, the calculation module 12 can create a chroma-brightness comparison table according to the set of parameters and the brightness comparison table, and in this embodiment, the calculation module 12 can also store the brightness comparison table in the storage module 10 . Wherein the chroma brightness comparison table is generated according to the set of parameters and the brightness comparison table. On the other hand, the luminance values of the image information of the present invention can also be stored in 8 bits and divided into 256 levels (the chroma values Cb and Cr are both distributed between 0 and 255). In this embodiment, the brightness comparison table can be generated according to the following formula:

$\mathrm{CYout}(x,\mathrm{the\; y})=\mathrm{Bound}{[f_C(\mathrm{St.},\mathrm{Sa},f\left(x\right))\mathrm{the\; y}-b_C(\mathrm{St.},\mathrm{Sa},f\left(x\right))]}_{\min }^{\max }\&times;256+\mathrm{Yout}\left(x\right),$ Where x is an integer between 0 and 255, and y is also an integer between 0 and 255, f _C (St, Sa, f(x)) = Sa×St×f(x)+(1-St) , b _C (St, Sa, f(x)) = 128×St×(Sa×f(x)-1), f(x) is a nonlinear function used to generate a gain relative to the input signal .

In this embodiment, the format of the chroma brightness comparison table in this embodiment can be as shown in Table 2 below:

Enter the chroma brightness value (C, Y) Output chroma, brightness value 0,0 Cyout[0,0] 0, 1 Cyout[0,1] ... ... 255, 255 Cyout[255, 255]

Table II

That is to say, through the chroma-brightness comparison table of the present invention, taking a luminance value and a chroma value as an example to search, a corresponding set of luminance values and chroma values can be obtained simultaneously in one search process.

Next, step S106 is executed to read image information from the storage module 10 by the processing module 14 . Subsequently, step S107 is executed, and the image format of the image information is determined by the processing module 14 .

In this embodiment, when the image format of the image information is determined to be the first format, the image processing method of the present invention proceeds to step S108, where the first format may be YCbCr 4:2:2, that is, YCbCr color space and the YCbCr sampling ratio is 4:2:2. As for the image information in the first format, the entire image information includes a plurality of pixels (for example: 1024*768 pixels), and two adjacent pixels in the first format correspond to a macro pixel.

For the convenience of calculation, each macro pixel can be formed by two processing pixels, and each processing pixel includes a chroma value and a first brightness value. Step S108 is executed, the processing module 14 searches the saturation and brightness comparison table stored in the storage module 10 according to the saturation value and the first brightness value of one of the processing pixels. Executing step S110, the processing module 14 obtains the adjusted saturation value and the first adjusted brightness value corresponding to the saturation value and the first brightness value from the saturation brightness comparison table, thereby completing the processing of the pixel. Saturation and brightness adjustment.

Next, the present invention can further execute step S112, and the processing module 14 judges whether each processing pixel of the image information has been adjusted, if not, repeat steps S108 to S110 for multiple times to perform all the adjustments in the image information Process pixels to make adjustments.

It should be noted that in the image processing method in the prior art, it is necessary to look up the brightness comparison table to adjust the brightness value, and to look up the saturation comparison table to adjust the saturation value. In the image processing method of the present invention, through the chroma-luminance comparison table of the present invention, a set of adjusted luminance values and chroma values can be obtained in one search process, thereby speeding up the process of image processing.

On the other hand, when the image format of the image information is determined to be the second format, the image processing method of the present invention proceeds to step S114, where the second format can be YCbCr 4:2:0, that is, the YCbCr color space and The sampling ratio of YCbCr is 4:2:0 or 4:1:1. The image information in the second format here, the image information in the second format here, the entire image information includes a plurality of pixels, and four adjacent pixels in the second format correspond to a macro pixel.

For the convenience of calculation and processing, each macro pixel can be formed by two processing pixels, and each processing pixel in the image information of the second format includes a saturation value, a first brightness value and a second brightness value. Step S114 is executed, the processing module 14 looks up the saturation and brightness comparison table stored in the storage module 10 according to the saturation value and the first brightness value of one of the plurality of processing pixels. Step S116 is executed, the processing module 14 respectively obtains the adjusted saturation value and the first adjusted brightness value corresponding to the saturation value and the first brightness value from the saturation and brightness comparison table. Next, step S118 is executed, the processing module 14 looks up the brightness comparison table stored in the storage module 10 according to the second brightness value of one of the processed pixels. Step S120 is executed, the processing module 14 obtains the second adjusted brightness value corresponding to the second brightness value from the brightness comparison table. In this way, the chroma and brightness adjustment of the processed pixel can be completed.

Next, the present invention can further execute step S122, and the processing module 14 judges whether each processing pixel of the image information has been adjusted. Process pixels to make adjustments.

It should be noted that, compared with the prior art, the three components of the color space are searched separately. In the image processing method of the present invention, through the chroma-luminance comparison table of the present invention, a set of adjusted luminance values and chroma values can be obtained in one search process. When the luminance value and color value of each processed pixel When the ratio of the brightness value is not 1:1, it can be combined with a lookup brightness comparison table to generate a second adjusted brightness value, so as to correspond to a variety of image formats, and make full use of the resources of different lookup tables to speed up the image The process of processing.

Next, the image processing method and image processing system 1 of the present invention can further execute step S124 to reset the set of parameters (St, Sa). When the image processing system 1 determines that the adjusted image information does not meet the actual needs or the user When manually updating the parameters via the input module 16, the set of parameters (St, Sa) can be reset. In this way, the image processing method and the image processing system 1 of the present invention can re-execute steps S102 to S122, and use the calculation module 12 to re-establish the brightness comparison table and the chroma-brightness comparison table according to the set of parameters reset, and then process The module 14 can adjust the image information based on the newly established brightness comparison table and saturation brightness comparison table.

To sum up, the image processing method and image processing system of the present invention can adjust a brightness value and a saturation value with one calculation process by setting up a brightness and saturation comparison table, thereby simplifying the calculation process of image processing and processing time.

Through the above detailed description of the preferred embodiments, it is hoped that the features and spirit of the present invention can be described more clearly, rather than limiting the scope of the present invention by the preferred embodiments disclosed above. On the contrary, the intention is to cover various modifications and equivalent arrangements within the scope of the appended claims of the present invention.

Claims (19)

1. A method of image processing, suitable for processing image information, said image information comprising a plurality of processing pixels, characterized in that said image processing method comprises the following steps: a) Set a set of parameters; b) establishing a brightness comparison table according to the set of parameters; c) establish a chroma brightness comparison table according to the set of parameters and the brightness comparison table; d) reading the image information; e) judging the image format of the image information; f) If the image format is the first format, using the chroma-brightness comparison table to generate an adjusted chroma value and the first luminance value corresponding to the chroma value and the first luminance value of one of the plurality of processed pixels. Once the brightness value is adjusted; and g) if the image format is the second format, using the chroma-brightness comparison table to generate an adjusted chroma value and a first luminance value corresponding to a chroma value and a first luminance value of one of the plurality of processed pixels. An adjusted brightness value, and using the brightness comparison table to generate a second adjusted brightness value corresponding to a second brightness value of one of the plurality of processed pixels. 2. The image processing method according to claim 1, wherein each processed pixel conforming to the first format includes a chroma value and a first brightness value respectively, wherein the step (f) is completed by the following steps , which contains: f1) Searching for the chroma-brightness comparison table according to the chroma value and the first luminance value of the corresponding one of the processed pixels; and f2) Obtaining the adjusted saturation value and the first adjusted brightness value respectively corresponding to the saturation value and the first brightness value from the saturation brightness comparison table. 3. The image processing method according to claim 2, wherein among the plurality of processing pixels conforming to the first format, two of the processing pixels form macropixels, and each macropixel corresponds to the image information of two adjacent pixels. 4. The image processing method according to claim 2, wherein the first format is a YCbCr color space format and the YCbCr sampling ratio is 4:2:2. 5. The image processing method according to claim 1, further comprising the following steps: f3) Step (f) is repeated to generate the adjusted chroma value and the first adjusted brightness value corresponding to each processed pixel, until the adjustment of the plurality of processed pixels of the image information is completed. the 6. The image processing method according to claim 1, wherein each processed pixel conforming to the second format includes a saturation value, a first brightness value and a second brightness value, wherein the step (g ) is accomplished through the following steps, which include: g1) Searching the chroma-brightness comparison table according to the chroma value and the first luminance value of the corresponding one of the processed pixels; g2) obtaining the adjusted saturation value and the first adjusted brightness value respectively corresponding to the saturation value and the first brightness value from the saturation brightness comparison table; g3) searching the brightness comparison table according to the second brightness value of the corresponding one of the processed pixels; and g4) Obtain the second adjusted brightness value corresponding to the second brightness value from the brightness comparison table. 7. The image processing method according to claim 6, wherein among the plurality of processing pixels conforming to the second format, two of the processing pixels form macro pixels, and each macro pixel corresponds to the image four adjacent pixels of information. 8. The image processing method according to claim 6, wherein the second format is a YCbCr color space format and the sampling ratio of YCbCr is 4:2:0 or 4:1:1. 9. The image processing method according to claim 1, further comprising the following steps: g5) Step (g) is repeated to generate the adjusted chroma value, the first adjusted luminance value and the second adjusted luminance value corresponding to each processed pixel, until all the image information is completed. The adjustment of multiple processing pixels is described. 10. The image processing method according to claim 1, further comprising the following steps: h0) reset said group of parameters; h1) re-establishing the brightness comparison table and the chroma brightness comparison table according to the set of parameters reset; and h2) Adjusting the image information by using the re-established brightness comparison table and the saturation brightness comparison table. 11. An image processing system, characterized in that it comprises: The storage module stores image information, and the image information includes a plurality of processing pixels; The calculation module is electrically connected with the storage module, the calculation module establishes a brightness comparison table according to a set of parameters, the calculation module establishes a chroma brightness comparison table according to the set of parameters and the brightness comparison table, and The brightness comparison table and the chroma brightness comparison table are stored in the storage module; and A processing module electrically connected to the storage module, the processing module reads the image information from the storage module and determines the image format of the image information, if the image format is the first format, the processing The module uses the chroma-brightness comparison table stored in the storage module to correspond to the chroma value and the first luminance value of one of the plurality of processed pixels to generate an adjusted chroma value and a first adjusted chroma value. Luminance value, if the image format is the second format, the processing module uses the chroma-luminance comparison table stored in the storage module to correspond to the chroma value of one of the processing pixels and a first brightness value, generating an adjusted chroma value and a first adjusted brightness value, and using the brightness comparison table to correspond to a second brightness value of one of the plurality of processing pixels to generate a second adjusted brightness value value. 12. The image processing system according to claim 11, wherein each processed pixel conforming to the first format respectively includes a chroma value and a first brightness value, and the processing module according to one of the corresponding The chroma value and the first luminance value of the processing pixel are searched for the chroma-brightness comparison table, and the values corresponding to the chroma value and the first luminance value in the chroma-brightness comparison table are respectively obtained. The adjusted saturation value and the first adjusted brightness value. 13. The image processing system according to claim 12, wherein the first format is a YCbCr color space format and the sampling ratio of YCbCr is 4:2:2. 14. The image processing system according to claim 12, wherein the processing module utilizes the chroma-brightness comparison table to generate the adjusted chroma value and the first processed pixel respectively corresponding to each processed pixel. Adjust the brightness value until the processing module completes the adjustment of the plurality of processing pixels of the image information. 15. The image processing system according to claim 11, wherein each processed pixel conforming to the second format includes a saturation value, a first brightness value, and a second brightness value, and the processing module according to the The chroma value and the first luminance value of one of the corresponding processing pixels are searched in the chroma-brightness comparison table, and the corresponding chroma value and the first luminance value in the chroma-brightness comparison table are respectively obtained. The adjusted saturation value of the brightness value and the first adjusted brightness value, the processing module searches the brightness comparison table according to the second brightness value of the corresponding one of the processed pixels, and obtains the The second adjusted brightness value corresponding to the second brightness value in the brightness comparison table. 16. The image processing system according to claim 15, wherein the second format is a YCbCr color space format and the sampling ratio of YCbCr is 4:2:0 or 4:1:1. the 17. The image processing system according to claim 15, wherein the processing module utilizes the chroma-brightness comparison table and the brightness comparison table to generate the adjusted chroma value corresponding to each processing pixel respectively , the first adjusted brightness value and the second adjusted brightness value, until the processing module completes the adjustment of the plurality of processing pixels of the image information. 18. The image processing system according to claim 11, further comprising: The input module is electrically connected with the calculation module, and the input module is used to set the group of parameters according to user operations. 19. The image processing system according to claim 11, wherein when the set of parameters is reset, the calculation module re-establishes the brightness comparison table and The chroma-brightness comparison table is also stored in the storage module, and the processing module uses the re-established brightness comparison table and the chroma-brightness comparison table to adjust the image information. the

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