Image forming apparatus employing technique that reduces amount of coloring material consumed

In image forming apparatus a phenomenon can occur in which developing material increases excessively at the edges of images formed by an image forming apparatus (called an edge effect), and a phenomenon can also occur in which developing material increases excessively at the following end areas of the image in a sub-scanning direction (called sweeping). The present invention suppresses an increase in the amount of developing material consumed by correcting pixels in which the amount of developing material consumed increases beyond a desired amount. The image forming apparatus 101 comprising: an image carrier 1; an exposure unit 7; a developing unit 3; a detection unit 12 configured to detect a physical parameter correlated with an increase in a developing material amount; specifying means for specifying a specific pixel, of the plurality of pixels that configure the image data; and correcting means (CPU 10) for correcting an image forming condition forming the specific pixel based on the physical parameter and a correction range parameter. Physical parameters may be ambient temperature or humidity, number of images formed, total operating time of the apparatus, remaining lifespan of the photosensitive drum, resistance value of the surface of the image carrier, remaining toner.