IMAGE READER

• Main Authors: TANAKA KAZUMOTO, ISHIHARA NORIYUKI
• Format: Patent
• Language: English
• Published: 11.06.1993
• Subjects: ELECTRIC COMMUNICATION TECHNIQUE; ELECTRICITY; PICTORIAL COMMUNICATION, e.g. TELEVISION

PURPOSE:To obtain a copy whose gradation characteristic is satisfactory even from any film of negative/positive by selecting an optimal gamma curve, and also, varying the quantity of light of alight source. CONSTITUTION:An enlarged projection image of a microfilm exposed by a light source 9 is subjected to image scan, fetched as a serial image signal in an analog value from an image sensor 1 by line synchronization, and inputted to an A/D converter 3 through an amplifier 2. Simultaneously, an offset voltage is also adjusted. Subsequently, the signal is made to an 8-bit digital signal, and is inputted to a gamma a correcting circuit 4 constituted of several pieces of RROMs. In this PROM, a gamma characteristic curve is stored by data measured in advance, and selected in accordance with base density by an SEL signal from a control part 11. Also, simultaneously, light quantity data EN/EP of light source light quantity control is also stored, read out and inputted to a light source driving part 10. A signal of an edge emphasizing circuit 5 is subjected to pseudo halftone processing and simple binarization processing by a halftone processing circuit 6 and a binarizing circuit 8, and the gradation characteristic is improved.