An image forming apparatus includes a document reader, a storage for storing image data, an image output unit and a control unit. The control unit includes a display image generator for generating a display image, a display panel and a control unit-side controller having a function of presenting the display image based on the image data input in a preview representation and an output processing function of implementing an output process. As the output processing function, two schemes are provided: a first output scheme wherein, when image data has been input through the input unit, the images are output after displaying the images to be output in a preview representation on a display panel, and a second output scheme wherein, when image data has been input through the input unit, the image is directly output without displaying the image to be output in a preview representation on the display panel.