| 摘要 |
PURPOSE:To enable formation of an image of high gradation and high resolution by a method wherein inputted image data are divided for each block as a unit, a threshold value block corresponding to each block in the ratio of 1 to 1 is employed, and the block is made to form a parallelogram having picture elements of (k) rows X(l) columns. CONSTITUTION:An image data signal 201 is formed into a semiconductor laser drive signal 203 by a window signal 202 for each one picture element. When the state of the drive signal is LOW, a laser light is pulsed. Thereby the application of light on a photosensitive body in the main scanning direction in continuous image formation is pulsed and energy is distributed in the same way as in the sub-scanning direction. Therefore the quantity of application of light for each one picture element is distribute in the shape of a circle, and an independent shape affected little by picture element interference can be obtained by forming it in the shape of a spot independent for each picture element of main scanning and sub-scanning. A threshold value block composed of picture elements of (k) rows X (l) columns is used as an intermediate tone processing method, the threshold value block composed of the picture elements of (k) rows and (l) columns is made to form a parallelogram in a means for shifting the same by a 1/2 picture element in each sub-scanning, and thereby an intermediate tone image being excellent in tonality can be obtained. |
