An image forming apparatus illuminates a pixel formation member with optical energy according to image data specifying a value for each pixel in the image. Some of the optical energy emitted to form a pixel is distributed over surrounding pixels; similarly, a pixel may receive peripheral optical energy that was emitted to form surrounding pixels. The amount of peripheral optical energy thus received is calculated, and the amount of optical energy emitted to form the pixel is adjusted to compensate for the peripheral optical energy, so that the total optical energy received by the pixel has the intended value. Image irregularities are thereby avoided, even if the image formation apparatus employs multiple light-emitting elements with different energy emission distributions.