US 6,553,151 B1 · Image forming apparatus for half-tone recording and shading compensation and half-tone image forming method

Abstract

An image forming apparatus with an image sensor for scanning a document to produce an electric signal; a converter for converting the electric signal into image data with a predetermined number of bits, m; a shading memory for storing output image data, scanned during a first mode operation with the converter, pixel by pixel, and also storing shading factors each corresponding to each pixel of the image data; a controller for reading the image data stored in the least significant address to the most significant address of the shading memory during the first mode of operation, finding shading factors for each pixel by dividing a preset maximum brightness value, M, by each of the sequentially read image data, then storing the shading factors in the shading memory, and for outputting the shading factors stored in the shading memory corresponding to each pixel of image data produced by the converter during a second mode of operation; a shading compensating circuit to multiply, pixel by pixel, the shading factors of the controller by the image data from the converter during the second mode of operation, to produce shading-compensated image data; and a half-tone processing circuit for producing a half-tone image from the output of the shading compensating circuit.

Claims10

Dependent claims

An image forming apparatus with an image sensor for scanning a document to produce an electric signal representative of an image from the document, comprising:

a converter for converting said electric signal to produce image data with a predetermined number of bits;
a shading memory unit for storing said image data on a pixel by pixel basis from a least significant address to a most significant address scanned during a first mode operation with said converter, and for storing shading factors each corresponding to each pixel from said image data;
a controller for sequentially reading said image data stored from the least significant address to the most significant address of said shading memory unit during said first mode of operation, calculating each shading factor for each pixel by dividing a preset maximum brightness value by said image data sequentially read from said shading memory unit, recording the shading factors in said shading memory unit, and for outputting the shading factors stored in said shading memory unit corresponding to each pixel of said image data produced by said converter during a second mode of operation;
a shading compensation unit for multiplying each pixel of said image data produced from said converter by a corresponding one of said shading factors during said second mode of operation to produce shading-compensated image data;
and
a half-tone processing unit for producing a half-tone image data from said shading-compensated image data produced from said shading compensating unit.

3 more elements

An image forming apparatus with an image sensor for scanning a document to produce an electric signal representative of an image from the document, comprising:

a converter for converting said electric signal to produce image data with a predetermined number of bits;
a shading memory unit for storing the image data obtained during a dummy scanning mode, and for storing shading factors corresponding to each pixel of the image data;
a first control unit for sequentially reading the image data stored from a least significant address to a most significant address in said shading memory unit during the dummy scanning mode, and finding a shading fact for each pixel by dividing a preset maximum brightness value by said image data sequentially read from said shading memory unit, and for storing the shading factors in said shading memory unit;
a second control unit for outputting the shading factors stored in said shading memory unit by address in a real scanning mode, and for outputting inverse values corresponding to a value of the predetermined bits;
a shading compensating unit to multiply, pixel by pixel, the shading factors of said second control unit, by the image data obtained from said converter during the real scanning mode to produce shading-compensated image data;
and
a half-tone processing unit for generating a half-tone image from the image data, using the shading-compensated image data of said shading compensating unit and the inverse values.

4 more elements

Dependencies are inferred from the claim text.

Image forming apparatus for half-tone recording and shading compensation and half-tone image forming method

Life of this patent

Image forming apparatus for half-tone recording and shading compensation and half-tone image forming method

Life of this patent

Abstract

Claims10