The iamge memory contains independently addressible storage elements. Image element data of an image divided into regions have associated addresses corresp. to the regions. A processor unit consisting of processor elements corresp. to the storage elements simultaneously processes the stored data for a number of image elements. Each processor element has a density convertor which converts the density of the image elements enabling the processor unit to perform density conversion of the image. It also contains a colour distinguishing device and a colour converter. Image element data are converted to a defined colour when the distinguishing device detects a preselected colour.
