Patent ID: 6750994
Filing Date: 2004-06-15
Classification: H04N

Abstract:
An exposure control device provided in an image reading device which reads a color image recorded in a negative film, said exposure control device comprising:an image reading processor that exposes an optical sensor to obtain image data corresponding to said color image, using more than two kinds of exposure times, which are different from each other, said image data being generated regarding said exposure times, respectively; a histogram generating processor that generates histograms showing distributions of pixel values of said image data, regarding each of said exposure times; a histogram selecting processor that obtains a maximum effective value in each of said histograms, and selects a first histogram, in which said maximum effective value does not exceed a predetermined value and is a greatest value among said histograms, and a second histogram corresponding to said image data obtained by using one of said exposure times which is subsequently shorter than said exposure time of said first histogram; and an optimum exposure time calculation processor that calculates an optimum exposure time based on said maximum effective values of said first and second histograms.