Method and device for gradation conversion

Abstract

Abstract PURPOSE:To perform gradation conversion corresponding to the characteristic of an original image setting the characteristic of a general gradation conversion as a base, by performing the gradation conversion in which a character having a standard gradation conversion curve, and a density distributed state on which the feature of the original image is affected, is fetched. CONSTITUTION:The titled device is constituted so that a picture signal V after shading correction is supplied selectively to a histogram counting circuit 17, and either side of a gradation correction circuit 18 including a RAM18a of lookup table system through a switch circuit 16. The circuit 17 finds an accumulated density histogram from density distribution in the original image 3, and a gradation conversion table is decided based on the above result, and it is stored in the RAM18a. A memory 32 stores data expressing a general standard gradation conversion curve. Therefore, by fetching the feature of the original image in the gradation conversion curve based on the density distributed state of the original image, after securing a natural reproduced image by the general multilevel conversion characteristic of the standard gradation conversion curve, it is possible to perform the optimum gradation conversion in which those characters are combined in a good balancing state.

Inventors

• 👤 Akihiro Nomura
• 👤 昭寛 野村
• 👤 Yasuo Kurusu
• 👤 康雄 来栖

Bibliographic Details