Title:
IMAGE READER
Document Type and Number:
Japanese Patent JP3550589
Kind Code:
B2
Abstract:
PURPOSE: To improve the S/N by identifying an effective original area with a method optimum to various originals to set the exposure to the effective area and to suppress gradation-jump by optimizing the amplification factor of analog signal amplification.
CONSTITUTION: An original effective area B and the read enable area A of an original are detected based on image information obtained by reading tentatively the original 1 with a set initial value and stored in a memory 10 and exposure is calculated by maximum luminance a(b) of the area A(B). In this case, the S/N is minimized by adjusting the exposure depending on the image pickup condition based on three factors as the luminous quantity of a light source 2, an aperture 3 and the storage time of a CCD 5 so that the effective original area B is set within the dynamic range of the CCD 5. Then the amplification factor of an analog signal amplifier 6 is obtained based on the maximum luminance of the original valid area so as to obtain the range equal to an input full range of an A/D converter 7 thereby obtaining smooth gradation expression without gradation jump by fully utilizing the input range of the A/D converter.
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Inventors:
Itsuto Kumoi
Soichi Ueda
Soichi Ueda
Application Number:
JP12576494A
Publication Date:
August 04, 2004
Filing Date:
May 16, 1994
Export Citation:
Assignee:
NIKON CORPORATION
International Classes:
H04N5/235; H04N1/40; H04N1/407; H04N5/253; H04N5/335; H04N5/351; H04N5/353; H04N5/355; H04N5/359; H04N5/372; H04N5/378; (IPC1-7): H04N5/235; H04N1/40; H04N1/407; H04N5/253; H04N5/335
Domestic Patent References:
| JP4034542A | ||||
| JP5211630A | ||||
| JP2141733A | ||||
| JP4151130A | ||||
| JP5260370A | ||||
| JP6098172A |
Other References:
秋山照雄 増田 功,印刷物の記事領域における文字の切出し,情報処理学会第21回全国大会,日本,情報処理学会,1980年,PRL80-70,P6-P16
Attorney, Agent or Firm:
Takeki Yamada