An image forming apparatus, comprising: an exposure device (2a-2d); a base toner amount determining unit configured to determine a base toner amount without taking edge effect into account, the base toner amount corresponding to a pixel value of image data for which gradation correction has not been performed; a laser profile applying unit configured to perform for the base toner amount a first spatial filter process corresponding to a laser profile of the exposure device (2a-2d) in one of the primary and secondary scanning directions, and thereafter for a result of this filter process the filter process in the other of the primary and secondary scanning directions; an edge emphasis amount determining unit configured to perform a second spatial filter process for the base toner amount after the first spatial filter process and thereby determine an edge emphasis amount correspond to the edge effect; a toner counter configured to count as a toner consumption amount a sum of the base toner amount after the first spatial filter process and the edge emphasis amount; characterized in that the edge emphasis amount determining unit selects a target pixel from pixels in a block as a spatial unit of the image processing and determines an edge emphasis amount of the target pixel and corresponding to the edge effect, wherein a range of the block edge pixels is a range within a predetermined distance from outermost sides of the block and is set in accordance with a size of the filters used in the first spatial and the second spatial filter process;the edge emphasis amount determining unit (a) performs the second spatial filter process for the base toner amount after the first spatial filter process by using a filter having filter coefficients in inverse proportion to squares of distances from the target pixel, and (b) sets as the edge emphasis amount a difference between a value obtained by the second spatial filter process and a value of the base toner amount of the target pixel. an exposure device (2a-2d); a base toner amount determining unit configured to determine a base toner amount without taking edge effect into account, the base toner amount corresponding to a pixel value of image data for which gradation correction has not been performed; a laser profile applying unit configured to perform for the base toner amount a first spatial filter process corresponding to a laser profile of the exposure device (2a-2d) in one of the primary and secondary scanning directions, and thereafter for a result of this filter process the filter process in the other of the primary and secondary scanning directions; an edge emphasis amount determining unit configured to perform a second spatial filter process for the base toner amount after the first spatial filter process and thereby determine an edge emphasis amount correspond to the edge effect; a toner counter configured to count as a toner consumption amount a sum of the base toner amount after the first spatial filter process and the edge emphasis amount; characterized in that the edge emphasis amount determining unit selects a target pixel from pixels in a block as a spatial unit of the image processing and determines an edge emphasis amount of the target pixel and corresponding to the edge effect, wherein a range of the block edge pixels is a range within a predetermined distance from outermost sides of the block and is set in accordance with a size of the filters used in the first spatial and the second spatial filter process;the edge emphasis amount determining unit (a) performs the second spatial filter process for the base toner amount after the first spatial filter process by using a filter having filter coefficients in inverse proportion to squares of distances from the target pixel, and (b) sets as the edge emphasis amount a difference between a value obtained by the second spatial filter process and a value of the base toner amount of the target pixel.