An image forming apparatus includes: a first holding unit that holds a pixel value data sequence in which each of the data sequences is formed by a pixel value and a range of the pixel value or by the pixel value, the range of the pixel value, reference to a pixel, and a range of the reference; a second holding unit that holds a transparency data sequence in which each of the one-dimensional data sequences is formed by a coefficient representing transparency of a pixel in the image element and a range of the coefficient or by the coefficient, the range of the coefficient, reference to coefficient, and a range of the reference; and an image generation unit that forms an image from the pixel value data sequence, and that generates information about transparency of the image from the transparency data sequence.