Block noise reduction device and image display device

A block noise reduction device for reducing block noise from a decoded image signal obtained by decoding a compressed and coded image signal, comprising:

• a moving picture region detection part for detecting a moving picture region within a frame of the decoded image signal;
• a frame correlation determination part for determining a level of correlation between the frame of the decoded image signal and a previous frame of the decoded image signal;
• a flat region detection part for detecting an image region in which a difference in brightness between neighboring pixels is small as a flat region from the decoded image signal;
• a high-frequency region detection part for detecting an image region including a high spatial frequency component as a high-frequency region from the decoded image signal;
• a smoothing processing part for performing smoothing processing to the decoded image signal corresponding to a predetermined region;
• and
• a processing region setting part for specifying an image region in which the smoothing processing part is to perform smoothing processing to the decoded image signal,
• wherein the processing region setting part sets at least a region in frames in which a correlation between frames is low or is a moving picture region, and which is a flat region and not a high frequency region in the decoded image signal, as a processing region, and the smoothing processing part does not perform processing in another region that is not the processing region,
• wherein the smoothing processing part performs smoothing processing to the decoded image signal and provides a transition region between the processing region and a region other than the processing region;
• and in the transition region, the decoded image signal that was subjected to the smoothing processing and the decoded image signal that is not subjected to the smoothing processing are switched while they are mixed, thereby these two image signals linked to each other smoothly.

An image display device using a block noise reduction device for reducing block noise from a decoded image signal obtained by decoding a compressed and coded image signal, comprising:

• wherein the block noise reduction device comprising:
• a moving picture region detection part for detecting a moving picture region within a frame of the decoded image signal;
• a frame correlation determination part for determining a level of correlation between the frame of the decoded image signal and a previous frame of the decoded signal;
• a flat region detection part for detecting an image region in which a difference in brightness between neighboring pixels is small as a flat region from the decoded image signal;
• a high-frequency region detection part for detecting an image region including a high spatial frequency component as a high-frequency region from the decoded image signal;
• a smoothing processing part for performing smoothing processing to the decoded image signal corresponding to a predetermined region;
• and
• a processing region setting part for specifying an image region in which the smoothing processing part is to perform smoothing processing to the decoded image signal,
• wherein the processing region setting part sets at least a region in frames in which a correlation between frames is low or is a moving picture region, and which is a flat region and not a high frequency region in the decoded image signal, as a processing region, and the smoothing processing part does not perform processing in another region that is not the processing region,
• wherein the smoothing processing part performs strong low-pass filter processing having a large block noise reduction effect as the correlation of the decoded image signals between frames is lower.

An image display device using a block noise reduction device for reducing block noise from a decoded image signal obtained by decoding a compressed and coded image signal, comprising:

• wherein the block noise reduction device comprising:
• a moving picture region detection part for detecting a moving picture region within a frame of the decoded image signal;
• a frame correlation determination part for determining a level of correlation between the frame of the decoded image signal and a previous frame of the decoded signal;
• a flat region detection part for detecting an image region in which a difference in brightness between neighboring pixels is small as a flat region from the decoded image signal;
• a high-frequency region detection part for detecting an image region including a high spatial frequency component as a high-frequency region from the decoded image signal;
• a smoothing processing part for performing smoothing processing to the decoded image signal corresponding to a predetermined region;
• and
• a processing region setting part for specifying an image region in which the smoothing processing part is to perform smoothing processing to the decoded image signal,
• wherein the processing region setting part sets at least a region in frames in which a correlation between frames is low or is a moving picture region, and which is a flat region and not a high frequency region in the decoded image signal, as a processing region, and the smoothing processing part does not perform processing in another region that is not the processing region,
• wherein the smoothing processing part performs smoothing processing to the decoded image signal and provides a transition region between the processing region and a region other than the processing region;
• and in the transition region, the decoded image signal that was subjected to the smoothing processing and the decoded image signal that is not subjected to the smoothing processing are switched while they are mixed, thereby these two image signals linked to each other smoothly.