Image compression device, image forming apparatus, examination apparatus, image compression method, and recording medium

An image compression method comprising:

• receiving image data and parameters for use in compression;
• performing compression processing on the image data based on information on the image data and the parameters using a quantization table for a brightness signal and a quantization table for a color signal;
• and
• setting the parameters,
• wherein the setting includes:
• setting an upper limit of the parameters of the quantization table for the color signal to a value that is less than or equal to α, and
• setting 90% or more of the parameters of AC components of the quantization table for the brightness signal to have values that are greater than or equal to the respective parameters of AC components of the quantization table for the color signal.

A non-transitory computer readable recording medium storing a program which causes a computer to perform an image compression method, the method comprising:

• receiving image data and parameters for use in compression;
• performing compression processing on the image data based on information on the image data and the parameters using a quantization table for a brightness signal and a quantization table for a color signal;
• and
• setting the parameters,
• wherein the setting includes:
• setting an upper limit of the parameters of the quantization table for the color signal to a value that is less than or equal to α, and
• setting 90% or more of the parameters of AC components of the quantization table for the brightness signal to have values that are greater than or equal to the respective parameters of AC components of the quantization table for the color signal.