1. An image forming apparatus comprising: reading means for reading an image of an original and generating an image signal corresponding to image information of the original; recording means for recording said image signal; image forming means for forming an image on a recording medium on the basis of the image signal generated by said reading means, said image forming means being capable of forming an image by the use of said recording means, and forming an image without the use of said recording means; and changing means for changing density of the image formed on said recording medium, wherein, when an image is formed without the use of said recording means, said changing means converts said image signal to change the density of said image, and when an image is formed by the use of said recording means, said changing means does not convert said image signal, but controls an image forming condition of said image forming means to change the density of said image when the density change is initiated in the course of the formation of said image.