Image processing apparatus, display apparatus, and computer-readable storage medium

A non-transitory computer-readable storage medium storing thereon a program that causes a computer to function as:

• a first gradation converting section that converts a gradation of an image signal input thereto;
• a sharpening process section that performs a sharpening process on the image signal after the gradation has been converted by the first gradation converting section;
• a second gradation converting section that converts the gradation of the image signal after the sharpening process has been performed;
• and
• a display control section that displays an image indicated by the image signal after the gradation has been converted by the second gradation converting section, in a display device, wherein
• the second gradation converting section converts the gradation of the image signal after the sharpening process has been performed, to perform a γ correction that cancels out a γ characteristic of the display device,
• a filter coefficient of a sharpening filter applied to the image signal by the sharpening process section is linear with respect to an output signal of the display device,
• the sharpening process section includes:
• a luminance calculating section that calculates a luminance of each of a plurality of pixels of the image indicated by the image signal;
• a difference calculating section that calculates a difference between the luminance and a luminance resulting from the sharpening filter being applied to the luminance, for each of the plurality of pixels;
• and
• a luminance changing section that changes the luminance of each of the plurality of pixels, based on the difference calculated by the difference calculating section, and
• the luminance changing section, for each of the plurality of pixels, obtains a difference value between a maximum value and an upper limit value of RGB values of the pixel and a difference value between a minimum value and a lower limit value of the RGB values of the pixel and, when an absolute value of the difference calculated by the difference calculating section is larger than a minimum difference value among the difference values, changes the luminance of the pixel based on the minimum difference value.