Method and apparatus for coding images with different image qualities for each region thereof, and method and apparatus capable of decoding the images by adjusting the image quality

Abstract

A region of interest is set within an image, the region of interest is tracked along motion of an object marked out within the image, and coding is performed in a manner that image quality differs between the region of interest and a region other than the region of interest. A wavelet transform unit applies a low-pass filter and a high-pass filter in the respective x and y directions of an original image, and divides the image into four frequency sub-bands so as to carry out a wavelet transform. A quantization unit quantizes, with a predetermined quantizing width, the wavelet transform coefficients outputted from the wavelet transform unit. A motion detector detects the motion of an object. A ROI setting unit moves a ROI region according to this motion of an object. In the case of moving images where a viewpoint changes, the background may be separated from the object and then the ROI region may be moved according to the motion of the object and the motion of the background.

1 . An image coding method characterized in that a region of interest is set within an image, the region of interest is tracked along motion of an object marked out within the image, and coding is performed in a manner that image quality differs between the region of interest and a region other than the region of interest. 
   
   
       2 . An image coding apparatus, including:
 a region-of-interest setting unit which sets a region of interest within an image;   a motion detector which detects motion of an object marked out within the image; and   a coding unit which codes images with image quality that differs between the region of interest and a region other than the region of interest,   wherein said region-of-interest setting unit has the region of interest follow the motion of an object.   
   
   
       3 . An image coding apparatus according to  claim 2 , further including an image quality setting unit which sets an image quality for the region other than the region of interest, based on an allotted code amount. 
   
   
       4 . An image coding apparatus according to  claim 2 , further including an object extracting unit which separates background in moving images where a viewpoint changes, wherein said region-of-interest setting unit has the region of interest follow the motion of an object, in accordance with motion of the background. 
   
   
       5 . An image coding apparatus according to  claim 3 , further including an object extracting unit which separates background in moving images where a viewpoint changes, wherein said region-of-interest setting unit has the region of interest follow the motion of an object, in accordance with motion of the background. 
   
   
       6 . An image pickup apparatus having an image pickup unit which acquires an image, wherein a region of interest is set within the image, the region of interest is tracked along motion of an object marked out within the image, and coding is performed in a manner that image quality differs between the region of interest and a region other than the region of interest. 
   
   
       7 . An image pickup apparatus, including:
 an image pickup unit which acquires an image;   a region-of-interest setting unit which sets a region of interest within an image;   a motion detector which detects motion of an object marked out within the image; and   a coding unit which codes images with image quality that differs between the region of interest and a region other than the region of interest,   wherein said region-of-interest setting unit has the region of interest follow the motion of an object.   
   
   
       8 . An image pickup apparatus according to  claim 6 , further including an image quality setting unit which sets an image quality for the region other than the region of interest, based on an allotted code amount. 
   
   
       9 . An image pickup apparatus according to  claim 7 , further including an image quality setting unit which sets an image quality for the region other than the region of interest, based on an allotted code amount. 
   
   
       10 . An image pickup apparatus according to  claim 6 , further including an object extracting unit which separates background in moving images where a viewpoint changes, wherein said region-of-interest setting unit has the region of interest follow the motion of an object, in accordance with motion of the background. 
   
   
       11 . An image pickup apparatus according to  claim 7 , further including an object extracting unit which separates background in moving images where a viewpoint changes, wherein said region-of-interest setting unit has the region of interest follow the motion of an object, in accordance with motion of the background. 
   
   
       12 . An image pickup apparatus, including:
 an image pickup unit which acquires an image;   a region-of-interest setting unit which sets a region of interest within the image;   a motion detector which detects motion of an object marked out within the image;   a coding unit which codes moving images in a manner that an image quality for region of interest differs from that for a region other than the region of interest; and   a decoding unit which decodes image data coded by said coding unit, wherein said region of interest setting unit has the region of interest follow the motion of an object.   
   
   
       13 . An image pickup apparatus according to  claim 12 , further including an image quality setting unit which sets an image quality for at least one of the region of interest and the region other than the region of interest by referring to a state of the apparatus.