Image processing apparatus, method of the same, and program

An image processing method of an image processing apparatus, the method comprising:

• allocating each pixel of an input image to any of respective partial regions obtained by dividing an entirety of a possible range of a luminance value into a plurality of units in a luminance direction at least in part on basis of the luminance value thereof, and allocating one pixel of the input image to a plurality of partial regions at a time of calculating frequency values representing a number of pixels allocated to the partial regions with respect to the respective partial regions, to update the frequency values of the partial regions;
• calculating a characteristic value representing a characteristic of a partial region;
• and
• performing edge-preserving smoothing on the input image by weighting and averaging the characteristic values in accordance with a distance in the luminance direction, using the calculated frequency value and the calculated characteristic value.

A program causing a computer to execute an image processing method, the method comprising:

• allocating each pixel of an input image to any of respective partial regions obtained by dividing the entirety of a possible range of a luminance value into a plurality of units in a luminance direction on the basis of the luminance value thereof, and allocating one pixel of the input image to a plurality of partial regions at the time of calculating frequency values representing the number of pixels allocated to the partial regions with respect to the respective partial regions, to update the frequency values of the partial regions;
• calculating a characteristic value representing a characteristic of the partial region;
• and
• performing edge-preserving smoothing on the input image by weighting and averaging the characteristic values in accordance with a distance in the luminance direction, using the frequency value and the characteristic value.