Image reading apparatus with black-level and/or white level corr

Details Image reading apparatus with black-level and/or white level corr Image reading apparatus with black-level and/or white level corr

1987-04-03

1991-08-06

Coles, Sr., Edward L.

Facsimile and static presentation processing

Facsimile

Specific signal processing circuitry

358464, 358466, 382 54, H04M 140

Patent

active

050382250

ABSTRACT:
An image reading apparatus such as facsimile or digital copying apparatus comprises: a lamp to illuminate an original; an image reading device such as CCD to read the original image line by line; a memory to store dark-output data (data output from a reading while the lamp is off) of the reading device by an amount of one line; and a correction circuit to correct the image data obtained by reading the image by the reading device every pixel on the basis of the data stored in the memory. A black level of the image data is corrected by the correction circuit and the memory stores the dark output data of the reading device before the image is read. The memory also stores the output data of the reading device when the lamp is off. With this apparatus, the unevenness of the output image signals which is caused due to a variation in dark currents obtained by photoelectrically reading the original image can be corrected by eliminating the unevennesses of the black and white levels of the CCD line sensor. Thus, a preferable output image can be derived.

REFERENCES:
patent: 4578711 (1986-03-01), White et al.
patent: 4589034 (1986-05-01), Yokomizo
patent: 4675533 (1987-06-01), Shimizu
patent: 4691240 (1987-09-01), Kurusu
patent: 4691365 (1987-09-01), Nagashima
patent: 4748677 (1988-05-01), Yokomizo

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