Image processing apparatus and method capable of suppressing image quality deterioration, and storage medium

Abstract

An image processing apparatus capable of suppressing image quality deterioration in an output image region determined based on reference pixel regions including image ends. The image processing apparatus includes a coefficient selection value generator that generates a coefficient selection value according to a filter coefficient changeover control signal supplied from a region information controller. In accordance with the coefficient selection value, filter coefficient sets are respectively output from coefficient tables. One of the filter coefficient sets is selected by a selector in accordance with a coefficient set selection value supplied from a coefficient set selection unit. Using filter coefficients that constitute the selected filter coefficient set, an image processor performs arithmetic processing on image data on a per pixel of interest basis while referring to peripheral pixels.

1 - 11 . (canceled) 
     
     
         12 . An image processing apparatus comprising:
 an image processing unit configured to perform arithmetic processing on image data on a per pixel of interest basis while referring to values of peripheral pixels; and   a selection unit configured to select a coefficient set from a plurality of coefficient sets different from each other in accordance with a location of a pixel of interest;   wherein said image processing unit is configured to perform the arithmetic processing on the image data by using the coefficient set selected by said selection unit.   
     
     
         13 . The image processing apparatus according to  claim 12 , wherein each of the plurality of coefficient sets has a plurality of coefficients in accordance with a location of at least one ineffective pixels included in the peripheral pixels (see paragraph numbers. 
     
     
         14 . The image processing apparatus according to  claim 12 , wherein said selection unit is configured to select the coefficient set in accordance with the location of the pixel of interest and at least one of a photographing condition indicated in the image data, a noise level detected from the image data, an edge condition of the image data, and a frequency characteristic of the image data. 
     
     
         15 . The image processing apparatus according to  claim 14 , wherein the photographing condition includes at least one of an ISO sensitivity, and a shutter speed. 
     
     
         16 . The image processing apparatus according to  claim 13 , wherein a coefficient value applied to each of the ineffective pixels is set to a value of 0. 
     
     
         17 . The image processing apparatus according to  claim 12 , wherein a coefficient value applied to a first effective pixel next to an ineffective pixel included in a first peripheral pixels having N ineffective pixels, is set to a value computed by adding respective coefficient values applied to a second effective pixel next to an ineffective pixel and a third effective pixel next to the second effective pixel, the second effective pixel and the third effective pixel being included in a second peripheral pixels having N−1 ineffective pixels. 
     
     
         18 . The image processing apparatus according to  claim 17 , wherein in a case where the value computed by adding respective coefficient values applied to the second effective pixel and the third effective pixels is smaller than a value applied to a fourth effective pixel next to the third effective pixel, the fourth effective pixels being included in the second peripheral pixels, the value set as the coefficient value applied to the first effective pixel is replaced with the value applied to the fourth effective pixel. 
     
     
         19 . An image processing method for controlling an image processing apparatus, the method comprising:
 an image processing step of performing arithmetic processing on image data on a per pixel of interest basis while referring to values of peripheral pixels; and   a selection step of selecting a coefficient set from a plurality of coefficient sets different from each other in accordance with a location of a pixel of interest;   wherein in the image processing step, the arithmetic processing is performed on the image data by using the coefficient set selected in said selection step.   
     
     
         20 . A non-transitory computer-readable storage medium which stores a computer-readable program for causing a computer to execute an image processing method for controlling an image processing apparatus, the method comprising:
 an image processing step of performing arithmetic processing on image data on a per pixel of interest basis while referring to values of peripheral pixels; and   a selection step of selecting a coefficient set from a plurality of coefficient sets different from each other in accordance with a location of a pixel of interest;   wherein in the image processing step, the arithmetic processing is performed on the image data by using the coefficient set selected in said selection step.   
     
     
         21 . An image processing apparatus comprising:
 an image processing unit configured to perform a filter process on image data on a per pixel of interest basis while referring to values of peripheral pixels;   a selection unit configured to select a filter unit from a plurality of filter units different in tap number from each other in accordance with a location of a pixel of interest;   wherein said image processing unit is configured to perform the filter process on the image data by using the filter unit selected by said selection unit.   
     
     
         22 . The image processing apparatus according to  claim 21 , wherein each of the plurality of filter units has a tap number in accordance with location of at least one ineffective pixel included in the peripheral pixels. 
     
     
         23 . The image processing apparatus according to  claim 21 , wherein said selection unit is configured to select the filter unit in accordance with the location of the pixel of interest and at least one of a photographing condition indicated in the image data, a noise level detected from the image data, an edge condition of the image data, and a frequency characteristic of the image data. 
     
     
         24 . The image processing apparatus according to  claim 23 , wherein the photographing condition includes at least one of an ISO sensitivity, and a shutter speed. 
     
     
         25 . An image processing method for controlling an image processing apparatus comprising:
 an image processing step of performing a filter process on image data on a per pixel of interest basis while referring to values of peripheral pixels;   a selection step of selecting a filter unit from a plurality of filter units different in tap number from each other in accordance with a location of a pixel of interest;   wherein in said image processing step, the filter process is performed on the image data by using the filter unit selected in said selection step.   
     
     
         26 . A non-transitory computer-readable storage medium which stores a computer-readable program for causing a computer to execute an image processing method for controlling an image processing apparatus, the method comprising:
 an image processing step of performing a filter process on image data on a per pixel of interest basis while referring to values of peripheral pixels;   a selection step of selecting a filter unit from a plurality of filter units different in tap number from each other in accordance with a location of a pixel of interest;   wherein in said image processing step, the filter process is performed on the image data by using the filter unit selected in said selection step.