Abstract:
The present invention is a general mode of a pixel-based adaptive blending method. By receiving several different input signals to generate a pixel and a blending factor of each signal, an output pixel can be generated depending on these pixels and blending factors. Thus, several different video and graphic images can be overlapped and blended flexibly on an output display.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention generally relates to a method for overlapping between graphic and video images, and more particularly to a method and system for overlapping and adjusting blending factors of various video/graphic images.  
           [0003]    2. Description of the Prior Art  
           [0004]    In the frame display field of the dynamic images, the single frame buffer architecture and the dual frame buffer architecture are usually used to merge and display graphic and video images. In general, the method of deciding to alternatively display video images or graphic images in the dual frame buffer architecture is to find chroma keying by looking up a particular color entry of the color lookup table. Besides, another method of that is black detection; in this regard, using the principle that black is mostly easy to be detected and therefore takes black as one kind of chroma keying. Both of the two methods described above take the pixels of graphic images as transparency and then video images will be displayed when a particular color (for instance, chroma keying or black) in the pixel streams is detected.  
           [0005]    [0005]FIG. 1 depicts a conventional method for overlapping between graphic and video images. A display frame  150  is composed of a video image  100  and a graphic image  110 , wherein the video image  100  and the graphic image  110  respectively send the corresponding pixels relative to the display frame  150  at the same time. The overlapped area  120  of the graphic image  110  can be filled with chroma keying, and using a detector  140  to detect whether it has chroma keying or not when the pixel streams of graphic images are sent to multiplexer  130 . When the detecting result shows that it has chroma keying, and then multiplexer  130  chooses pixels of the video image  100  for output; otherwise, choosing pixels of the graphic image  110  for output.  
           [0006]    Although we can use the method described above to make video images to be overlapped with graphic images, or blending video and graphic images with a certain blending factor for achieving an effect of transparency mix, but its flexibility is restricted. In this regard, for instance when using ¼ RGB color value of a video image and ¾ RGB color value of a graphic image as the pixels of a particular area for output, resulting in an effect of overlapping and semi-transparency, but the method with a fixed blending factor is less flexibility in the applications of dynamic images. For instance, when requiring blending of overlapped area in different ways of transparency, or producing an effect of fade-in and fade-out, the flexibility of the method described above is restricted. Besides, the prior art is usually restricted by overlapping of a graphic image and a video image or overlapping of a graphic image and a frame; moreover, when the source of the frame has various graphic images or video images, the flexibility of the above-mentioned method is restricted and not enough to the applications of dynamic images.  
         SUMMARY OF THE INVENTION  
         [0007]    The present invention provides an adaptive pixel-based blending method which includes the steps, respectively acquiring a corresponding pixel and an adjustable blending factor in accordance with a plurality of input signals; and generating an output pixel in accordance with a blending method.  
           [0008]    The present invention also provides an adaptive pixel-based blending system which includes the means, a pixel and blending factor generating unit which is configured to respectively generate a corresponding pixel and a blending factor in accordance with a plurality of input signals; and a mixer which is configured to generate an output pixel in accordance with a blending method, the plurality of pixels and the plurality of blending factors.  
           [0009]    Besides, the present invention provides a video-processing chip which includes the means, a blending factor generating module which is configured to respectively generate a plurality of corresponding blending factors in accordance with a plurality of input signals; and a mixer which is configured to generate an output pixel in accordance with a plurality of source pixels and the plurality of blending factors.  
           [0010]    Accordingly, the method and system according to the embodiments of the present invention can dynamically change the blending factor of pixels by a programmable procedure in the pixels-extracting process; and it is therefore increase the flexibility and the applications of overlap between multi-input video images and graphic images.  
         BRIEF DESCRIPTION OF THE DRWAING  
         [0011]    The present invention can be best understood through the following description and accompanying drawings, wherein:  
           [0012]    [0012]FIG. 1 schematically shows the diagram of conventional method for overlapping between graphic and video images;  
           [0013]    [0013]FIG. 2 schematically shows the flow chart of the adaptive pixel-based blending method according to one preferred embodiment of the present invention;  
           [0014]    [0014]FIG. 3A schematically shows the diagram of the adaptive pixel-based blending system according to one preferred embodiment of the present invention;  
           [0015]    [0015]FIG. 3B schematically shows the diagram of the adaptive pixel-based blending system according to another preferred embodiment of the present invention; and  
           [0016]    [0016]FIG. 4 schematically shows the diagram of the video-processing chip according to one preferred embodiment of the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0017]    Some appropriate and preferred embodiments of the present invention will now be described in the following. It should be noted, however, that the embodiment is merely an example and can be variously modified without departing from the range of the present invention.  
         [0018]    It is to be understood, however, that the drawings, which are not to scale, are designed for the purpose of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims.  
         [0019]    [0019]FIG. 2 schematically shows the flow chart of the adaptive pixel-based blending method according to one embodiment of the present invention. First, step  200  is respectively acquiring a corresponding pixel and an adjustable blending factor in accordance with each of a plurality of input signals. When each of the input signals is a pixel index value of indirect colors, thus the way that looking up a color lookup table can generate each pixel of them. For instance, acquiring a corresponding pixel by verifying the pixel index value with a corresponding color entry of the color lookup table, which can dynamically change the contents of that by a programmable procedure. And then, the adjustable blending factor can be formed by partial bits of the pixel value. Next, step  220  is generating an output pixel in accordance with a blending method, wherein the output pixel is generated by the blending method in accordance with the pixels of each signal and the blending factor. For instance, each of signal A, B and C respectively generates pixel  1 ,  2  and  3 , and each pixel of them is composed of a red value (R), a green value (G) and a blue value (B). Otherwise, each pixel of them is composed of a luminance value (L) and a chrominance value (C). For instance, the values of R, G, B are respectively (50, 50, 50), (100, 100, 100) and (200, 200, 200), and each of the blending factors is respectively 200%, 100% and 25%, thus multiplying each of the pixel values by the blending factors. It is therefore that we can get each of the blending values, which is respectively (100, 100, 100), (100, 100, 100) and (50, 50, 50); moreover, adding them for obtaining an output pixel, (250, 250, 250). It should be appreciated that, each of the blending values is limited to a range, for instance, each of the blending values is restricted that not greater than a maximum color value and the output pixel is limited to being not greater than the maximum color value; otherwise, an overflow condition will occur. Further, the maximum color value represents the maximum of the pixels; for instance, the maximum color value is 255 when using in a 256-colors environment, which the color range is from 0 to 255. When the pixel is composed of various pixel values, all of the blending values and the output pixel value is restricted within the maximum color value of the output pixel value. For instance, when each of the maximum color values of the output red, green and blue value of the output pixel, is respectively 63, 31 and 63; and then each of RGB values of each blending value (generated by the pixels of all signals and the blending factors) is respectively limited to 63, 31 and 63. Furthermore, each of RGB values of the output pixel (generated by the way that adding each blending value) is also respectively limited to 63, 31 and 63.  
         [0020]    Besides, the contents of various signals can generate the pixels with the same color values and different blending factors by dynamically changing the contents of the color entries; moreover, when the contents of various signals are invariable, it can achieve a special display effect by dynamically changing the blending factor. For instance, when the contents of a signal are A, B, C, D and E, generating the pixels (that are all color 1) by verifying the color lookup table, while the blending factors are 100%, 75%, 50%, 25% and 0% respectively; thus the pixels generated by the signal will be gradually changed from color 1 to diluted color at different timing. And finally, it generates a fade-out effect.  
         [0021]    Therefore, each of the signal sources simply sends the signal contents related with the pixels, and the same pixels with different blending factors are sent in different contents of signals; thus there is no need to send the information of both pixels and blending factors. Further, it will save the storage space and the communication cost of source signals. For instance, when each blending factor related with each pixel requires 8 bits to represent a frame with 1024×768 resolution and then each frame requires 6,291,456 bits, results in large cost of displaying 30 frames per second.  
         [0022]    [0022]FIG. 3A schematically shows the diagram of the adaptive pixel-based blending system according to one preferred embodiment of the present invention. The system includes a pixel and blending factor generator  300 , configured to respectively generate a corresponding pixel and a blending factor in accordance with a plurality of input signals; and a mixer  340 , configured to generate an output pixel in accordance with a blending method, the plurality of pixels and the plurality of blending factors. And next, FIG. 3B schematically shows the diagram of the adaptive pixel-based blending system according to another preferred embodiment of the present invention. The system includes a pixel and blending factor generator  300 , wherein the generator  300  further includes various programmable lookup tables  3101 ˜ 310 N, configured to output corresponding pixels in accordance with a corresponding color entry of a color lookup table (which is in response to each input signal). The system further includes various blending factor generators  3201 ˜ 320 N, each blending factor generator is configured to receive an input signal for generating corresponding blending factors. The blending method and other related details of the embodiment is the same as the former embodiment, and thus there is no need to give unnecessary details.  
         [0023]    [0023]FIG. 4 schematically shows the diagram of the video-processing chip according to one preferred embodiment of the present invention. The video-processing chip includes a blending factor generating module  420 , configured to respectively generate a plurality of corresponding blending factors in accordance with a plurality of input signals; and a mixer  440 , configured to generate an output pixel in accordance with a plurality of source pixels and the plurality of blending factors. Further, the blending factor generating module  420  includes various blending factor generators  4201 ˜ 420 N, and the video-processing chip further includes a frame buffer  440  and a color lookup table module  410 . Moreover, the frame buffer  440  is configured to save the plurality of pixels of video/graphic images and provide the blending factor generating module  420  with the plurality of input signals. Furthermore, the color lookup table module  410  also includes a plurality of lookup tables  4101 ˜ 410 N, each lookup table is configured to save a plurality of color entries and then be extracted by the plurality of input signals; and the contents of each color entry are pixels.  
         [0024]    While this invention has been described with reference to illustrative embodiments, this description does not intend or construe in a limiting sense. Various modifications and combinations of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is therefore intended that the appended claims encompass any such modifications or embodiments.