Circuit and method for modifying a region of an encoded image

Abstract

A video processing circuit includes a processor that receives an encoded image having first and second regions, decodes the first region of the image, modifies the decoded first region, and re-encodes the modified first region. Such a circuit allows one to modify a region of an image by decoding and re-encoding only that region instead of the entire image. For example, if one wishes to overlay an EPG on a bottom portion of a video frame, then the circuit can decode only the EPG and the bottom portion of the frame, overlay the decoded EPG on the bottom frame portion, and re-encode the overlaid bottom frame portion. Therefore, this technique often reduces the processing time, and thus the cost and complexity of the processing circuit, as compared to a circuit that decodes and re-encode the entire frame during an image overlay process.

1 . A video processing circuit comprising a processor operable to: 
 receive an encoded base image having first and second regions and an encoded overlay image;    decode the overlay image and the first region of the base image;    combine the decoded overlay image with the decoded first region of the base image to form a modified first region of the base image; and    re-encode the modified first region of the base image.    
     
     
         2 . The video processing circuit of  claim 1  where the processor is operable to combine the encoded second region of the base image and the re-encoded modified first region of the base image to generate an encoded modified base image.  
     
     
         3 . The video processing circuit of  claim 1  where the processor is operable to: 
 decode the overlay image and the first region of the base image into a transform domain; and    combine the decoded overlay image with the decoded first region of the base image in the transform domain.    
     
     
         4 . The video processing circuit of  claim 1  where the processor is operable to: 
 decode the overlay image and the first region of the base image into a pixel domain; and    combine the decoded overlay image with the decoded first region of the base image in the pixel domain.    
     
     
         5 . The video processing circuit of  claim 1  where the overlay image comprises a program guide.  
     
     
         6 . The video processing circuit of  claim 1  comprising: 
 a buffer; and    where the processor is operable to store the encoded second region of the base image and the re-encoded modified first region of the base image in the buffer as an encoded modified base image.    
     
     
         7 . A video processing circuit, comprising: 
 a display output;    a processor operable to receive an encoded base image having first and second regions, an encoded overlay image, and an overlay signal, the processor being coupled to the display output;    where the processor, responsive to the overlay signal, is operable to: 
 decode the overlay image and the first region of the base image;  
 combine the decoded overlay image with the decoded first region of the base image to form a modified first region of the base image;  
 re-encode the modified first region of the base image;  
 combine the encoded second region of the base image and the re-encoded modified first region of the base image to form an encoded modified base image; and  
 provide the encoded modified base image on the display output; and  
 provide the encoded base image on the display output in the absence of the overlay signal.  
   
     
     
         8 . The video processing circuit of  claim 7  where the overlay image comprises a program guide.  
     
     
         9 . The video processing circuit of  claim 7  where the overlay signal comprises a remote-control overlay signal.  
     
     
         10 . The video processing circuit of  claim 7  comprising: 
 a buffer; and    where the processor is operable to combine the encoded second region of the base image and the re-encoded modified first region of the base image by storing the encoded second region and the re-encoded modified first region in the buffer.    
     
     
         11 . A video processing circuit, comprising a processor operable to: 
 receive encoded images each having respective first and second regions, each of the first and second regions divided into respective image subregions;    decode at least one of the image subregions in the first region of an image;    modify the decoded image subregion; and    re-encode the modified image subregion.    
     
     
         12 . The video processing circuit of  claim 11  where the processor is operable to re-encode the modified image subregion as an intracoded subregion.  
     
     
         13 . The video processing circuit of  claim 11  where the processor is operable to re-encode the modified image subregion as non-intracoded subregion having a motion vector with a location value of zero.  
     
     
         14 . The video processing circuit of  claim 11  where the processor is operable to: 
 receive an overlay image divided into overlay subregions;    decode at least one of the overlay subregions;    modify the decoded image subregion by combining the decoded image subregion with the decoded overlay subregion to form the modified image subregion; and    re-encode the modified image subregion by intra-coding the modified image subregion.    
     
     
         15 . The video processing circuit of  claim 11  where the processor is operable to: 
 receive an overlay image divided into overlay subregions;    decode at least one of the overlay subregions;    modify the decoded image subregion by combining the decoded image subregion with the decoded overlay subregion to form the modified image subregion; and    re-encode the modified image subregion as a non-intra-coded subregion having a motion vector with a location value of zero.    
     
     
         16 . The video processing circuit of  claim 11  where the processor is operable to: 
 receive overlay images divided into respective overlay subregions, the overlay images having a scroll rate;    decode at least one of the overlay subregions;    modify the decoded image subregion by combining L the decoded image subregion with the decoded overlay subregion to form the modified image subregions; and    re-encode the modified image subregion as non-intra-coded subregion having a motion vector with a value based on the scroll rate.    
     
     
         17 . The video processing circuit of  claim 11  where the image subregions each comprise a respective macro block.  
     
     
         18 . A video processing circuit, comprising: 
 a display output;    a processor coupled to the display output and operable to: 
 receive a sequence of encoded images each having respective first and second regions, the sequence including intra-coded and non-intra-coded images;  
 decode the first region of an intra-coded image;  
 modify the decoded first region;  
 re-encode the modified first region;  
 combine the encoded second region of the intra-coded image and the reencoded modified first region of the intra-coded image to form an encoded modified intra-coded image; and  
 provide the encoded modified intra-coded image on the display output.  
   
     
     
         19 . The video processing circuit of  claim 18  where the processor is operable to uncouple the respective first and second regions of the nonintra-coded images from the display output.  
     
     
         20 . The video processing circuit of  claim 18  where the processor is operable to uncouple the respective second regions of the non-intracoded images from the display output.  
     
     
         21 . The video processing circuit of  claim 18  where the processor is operable to: 
 decode the first region of a non-intra-coded image;    modify the decoded first region of the non-intra-coded image;    re-encode the modified first region of the non-intra-coded image;    combine the encoded second region of the intra-coded image and the reencoded modified first region of the non-intra-coded image to form an encoded modified image; and    provide the encoded modified image on the display output.    
     
     
         22 . A method, comprising: 
 decoding an encoded overlay image and a first region of an encoded base image having the first region and a second region;    combining the decoded overlay image with the decoded first region of the base image to form a blended first region of the base image; and    re-encoding the blended first region of the base image.    
     
     
         23 . The method of  claim 22  comprising: 
 combining the encoded second region of the base image and the re-encoded first region of the base image to form an encoded modified base image.    
     
     
         24 . The method of  claim 22  where: 
 the decoding comprises decoding the overlay image and the first region of the base image into a transform domain; and    the combining comprises combining the decoded overlay image and the decoded first region in the transform domain.    
     
     
         25 . The method of  claim 22  where: 
 the decoding comprises decoding the overlay image and the first region of the base image into a pixel domain; and    the combining comprises combining the decoded overlay image and the decoded first region in the transform domain.    
     
     
         26 . The method of  claim 22  where the overlay image comprises a program guide.  
     
     
         27 . A method, comprising: 
 decoding at least one image subregion in a first region of an encoded image having the first region and a second region divided into respective image subregions;    modifying the decoded image subregion; and    re-encoding the modified image subregion.    
     
     
         28 . The method of  claim 27  comprising: 
 receiving an overlay image divided into respective overlay subregions;    decoding at least one of the overlay subregions;    where the modifying comprises combining the decoded image subregion with the decoded overlay subregion to form the modified image subregion; and    where the re-encoding comprises intra coding the modified image subregion.    
     
     
         29 . The method of  claim 27  comprising: 
 receiving an overlay image divided into respective overlay subregions;    decoding at least one of the overlay subregions;    where the modifying comprises combining the decoded image subregion with the decoded overlay subregion to form the modified image subregion; and    where the re-encoding comprises non-intra coding and generating a motion vector for the modified image subregion, the motion vector having a location value of zero.    
     
     
         30 . The method of  claim 27  comprising: 
 receiving an overlay image divided into respective overlay subregions, the overlay images having a scroll rate;    decoding at least one of the overlay subregions;    where the modifying comprises combining the decoded image subregion with the decoded overlay subregion to form the modified image subregion; and    where the re-encoding comprises non-intra coding and generating a motion vector for the modified image subregion, the motion vector having a location value based on the scroll rate.    
     
     
         31 . A method. comprising: 
 receiving an encoded image having first and second regions;    decoding the first and second regions;    changing the resolution of the first and second regions; modifying the first region after changing its resolution; and    re-encoding the modified first region.    
     
     
         32 . The method of  claim 31  where the changing comprises reducing the resolution of the first and second regions.  
     
     
         33 . The method of  claim 31  comprising combining the encoded second region of the image and the re-encoded first region of the image to generate an encoded modified image.  
     
     
         34 . The method of  claim 31  where the changing comprises changing the resolution of the first and second regions in the transform domain.  
     
     
         35 . A method, comprising: 
 receiving an encoded base image and an encoded overlay image;    decoding the base image and the overlay image; and    combining the decoded base image and the decoded overlay image in the transform domain to form a modified image.    
     
     
         36 . The method of  claim 35  comprising re-encoding the modified image.  
     
     
         37 . The method of  claim 35  where the combining comprises alpha blending the decoded base image and the decoded overlay image.