| 摘要 |
PURPOSE:To make possible revisualization of a satisfactory intermediate tone, even if the density of an output image is changed by forming a corrected image data into a latent image based on a pulse width modulation signal and adjusting a correction means when either of a charge value of transfer material, a projected light value to a photosensitive element and a bias value to be applied for development is selected by a change means during a development process. CONSTITUTION:RAM used as a gradation correction means contains a gradation correction table. The table (d) is obtained by synthesizing CCD input characteristics (a), printer output characteristics (c) desired gradation curve (b) when an original is copied. If this gradation correction table is used, an original image is converted as shown by (b) to form an output image. If the output characteristics change as shown by a dot line (A), the content of the gradation correction table is correctively adjusted as shown by A'. In addition, if the output characteristics change as shown by a dot line (B), the content of the gradation correction table is corrected as shown by B'. Consequently, a halftone area of an input image holds a state before changing a development bias VDC. That is, the gradation change of an intermediate tone image is prevented. |
