Image processing method using sparse coding, and non-transitory computer-readable storage medium storing image processing program and image processing apparatus

A non-transitory computer-readable storage medium storing an image processing program that causes a computer to execute an image process of producing, from a first image, a second image by sparse coding, the image process comprising when an average pixel value in a partial region of an image is referred to as a DC component, and a component acquired by subtracting the DC component from a pixel value distribution in the partial region is referred to as an AC component:

• producing, from the first image, a processing intermediate image having a pixel value distribution in which a difference among multiple pixel values in a partial region of the processing intermediate image is equal to the DC component in a partial region of the first image corresponding to the partial region of the processing intermediate image;
• performing a first process of acquiring, by using the AC component in a first partial region extracted in the processing intermediate image and a basis produced by dictionary learning, the AC component in a second partial region;
• and
• performing a second process of acquiring a difference among multiple pixel values in the second partial region as the DC component in a partial region of the second image corresponding to the second partial region,
• wherein the image process repeats the first and second processes with changing a position of extracting the first partial region in the processing intermediate image to acquire the DC components in multiple partial regions of the second image.

An image processing apparatus configured to produce, from a first image, a second image by sparse coding, the apparatus comprising when an average pixel value in a partial region of an image is referred to as a DC component, and a component acquired by subtracting the DC component from a pixel value distribution in the partial region is referred to as an AC component:

• an image producer configured to produce, from the first image, a processing intermediate image having a pixel value distribution in which a difference among multiple pixel values in a partial region of the processing intermediate image is equal to the DC component in a partial region of the first image corresponding to the partial region of the processing intermediate image;
• a first processor configured to perform a first process of acquiring, by using the AC component in a first partial region extracted in the processing intermediate image and a basis produced by dictionary learning, the AC component in a second partial region;
• and
• a second processor configured to perform a second process of acquiring a difference among multiple pixel values in the second partial region as the DC component in a partial region of the second image corresponding to the second partial region,
• wherein the image producer is further configured to repeat the first and second processes with changing a position of extracting the first partial region in the processing intermediate image to acquire the DC components in multiple partial regions of the second image.