| 摘要 |
PURPOSE:To reduce the effect of uneven density at a low frequency caused by a mechanical signal by providing an output of a tone patch stored in a test pattern memory with a picture output means and generating a gradation correction curve based on a picture signal of the test pattern obtained through the read by a picture entry means. CONSTITUTION:A single tone patch with consecutive gradation is used for a test pattern(TP) and stored in a test pattern memory 526. When the calibration mode is set, the TP is read from the memory 526 and printed out onto a white paper sheet via a laser write section 53. When the paper is set on an original platen and a start key is depressed, a picture read section 51 scans the TP for each line and a picture processing section 52 applies LOG transformation to the scanned data and the result is fed to a CPU 523. The CPU 523 averages plural lines of sampling data for each picture element, smoothes and obtains its inverse function and stores the result in a gradation correction LUT 522 as a gradation correction curve. |
