| 摘要 |
PURPOSE:To correct excellently contrast regardless of the density range of an original picture only by setting up one kind of correction data. CONSTITUTION:The density range which has ''0'' for reference white density W0 and ''2.1'' for reference black density B0 is divided by eight bits (256 steps) and density data of respective density steps are used as addresses to store 256 correction data in ROM1 previously. A generation part 2 for gradation correction data is equipped with a microprocessor (MPU)21 and RAM22, and correction data are read out of the ROM1 according to white density data WD and BD which are supplied externally and processed as specified to output eight-bit gradation correction data K. The MPU21 reads white correction data HW out of the ROM1 firstly by using the white density data WD as an address and performs arithmetic in case of YN=HW on the basis of an equation I.
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