Provided are an image processing apparatus and an image processing method, for compressing an image by using a representative-color-based compression which includes dividing an image to be compressed into plural blocks, extracting representative colors from each of the blocks, and assigning each pixel in the blocks one of the representative colors. The image processing apparatus includes: a compressing section configured to perform the following operations. The operations include generating color compression data by performing a representative-color-based compression on a color input image, generating first monochrome compression data by performing a monochrome conversion of representative colors extracted in the generating the color compression data, generating second monochrome compression data by performing a monochrome conversion and then a representative-color-based compression on the color input image, generating difference data by comparing the first and second monochrome compression data, and outputting the color compression data and the difference data.