Image adjustment device, image adjustment method, and computer readable medium

An image adjustment device comprising:

• a display unit configured to display an image;
• an operation unit that is a man-machine interface;
• and
• a tone adjustment unit configured to adjust luminance values of first image data having a first dynamic range to luminance values of second image data having a second dynamic range, wherein
• the tone adjustment unit adjusts the luminance values of the first image data to the luminance values of the second image data by using a tone curve having a relationship log(Y)=γ(X)log(X), in which X represents an input, and Y represents an output, and
• the characteristics of the tone curve are adjustable via the operation unit while the display unit displays the tone curve.

An image adjustment method comprising:

• a tone adjustment step for adjusting luminance values of first image data having a first dynamic range to luminance values of second image data having a second dynamic range smaller than the first dynamic range, wherein
• in the tone adjustment step, the following relationship is assumed to be satisfied:
• LO=DO+Da=TD(I)+Da=TL(I), in which I represents a luminance value normalized to have a maximum value of one in the first image data, DO represents a luminance value normalized to have a maximum value of one in the second image data, Da represents a luminance value under ambient light during viewing, LO represents a luminance value of the second image data while taking into consideration effects of the ambient light during viewing, TD(I) represents a tone curve used for conversion, and TL(I) represents a tone curve taking into consideration the environment, and
• in the tone adjustment step, the tone curve TD(I) is adjusted so that a function representing an inclination γ(I) after converting LO=TL(I) to a double logarithmic plot is non-zero over the entire dynamic range.

A non-transitory computer readable medium storing a program for causing a computer to function as:

• a tone adjustment unit configured to adjust luminance values of first image data having a first dynamic range to luminance values of second image data having a second dynamic range smaller than the first dynamic range, wherein
• the tone adjustment unit assumes that the following relationship is satisfied:
• LO=DO+Da=TD(I)+Da=TL(I), in which I represents a luminance value normalized to have a maximum value of one in the first image data, DO represents a luminance value normalized to have a maximum value of one in the second image data, Da represents a luminance value under ambient light during viewing, LO represents a luminance value of the second image data while taking into consideration effects of the ambient light during viewing, TD(I) represents a tone curve used for conversion, and TL(I) represents a tone curve taking into consideration the environment, and
• the tone curve TD(I) is adjusted so that a function representing an inclination γ(I) after converting LO=TL(I) to a double logarithmic plot is non-zero over the entire dynamic range.