Image analysis – Image enhancement or restoration – Variable threshold – gain – or slice level
Reexamination Certificate
1998-07-06
2001-08-28
Lee, Thomas D. (Department: 2724)
Image analysis
Image enhancement or restoration
Variable threshold, gain, or slice level
C382S271000
Reexamination Certificate
active
06282325
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image binarization technique and, more particularly to an image processing technique for binarizing an image scanned by a shuttle type scanner in a multifunctional machine using a small amount of memory.
2. Description of the Related Art
Conventionally, a multifunctional machine is equipped with a scanner, a printer, a modem, a computer, etc. The multifunctional machine prints data scanned by the scanner or data transmitted from another system through the modem using the printer, or stores the data in a hard disk of the computer. The multifunctional machine is manufactured to perform the functions of a facsimile machine, printer, scanner and a copying machine.
There are two types of multifunctional machines, i.e., a shuttle type and an array type. The array type which supports a rapid scanning of a document is high in price. On the contrary, the shuttle type scans the document slower than the array type. However, since the shuttle type is low in cost, it has widely been used.
The scanning operation of a shuttle type scanner is explained below.
First, a part of the document is scanned by the scanner of the multifunctional machine. The unit scanned by the scanner is called a slice.
The size of the slice is decided by the number of pixels which are scanned at a time according to the number of charged coupled devices (CCDs) mounted on the scanner. For example, assuming that the number of CCDs of the scanner is 160 pixels in the longitudinal direction and the number of CCDs is 1 in the horizontal direction, then the size of the slice is 160×1.
Scanning the document is performed by moving the scanner from the most left edge of the document to the most right edge of the document per unit of slice. The scanner performs scanning by dividing the document per unit of band. The band indicates the amount of data of the document which is scanned once in the horizontal direction by the scanner.
In order to transmit data contained in the document through the facsimile machine after scanning the document, the scanned document is changed to data values of 0 or 1. Generally, the data scanned by the scanner is a gray color and has 256 values, i.e., 0 to 255. The values are expressed by 8 bits and the process for changing the values into binary values is called a binarization.
The binarization process includes two different methods, namely, an error diffusion method (EDF) and a threshold value method. Since these methods are well known to persons skilled in the art, a detailed description thereof has been omitted.
The binarization process according to the EDF method using a mask having 3×3 pixels in a shuttle type scanner is explained below.
In order to binarize one target pixel of data which has been scanned, the data binarization is performed by diffusing an error value generated when binarizing 1 pixel to 8 pixels neighboring the target pixel around the target pixel according to the weight of each mask cell. The aforesaid technique is called data binarization by the EDF method.
Generally, in the case of performing the binarization, since it is necessary to know the values of neighboring pixels before performing the EDF operation, scanned first band data and second band data containing an S region are stored and controlled. In addition, by substituting the value of a P region with a neighboring pixel value according to the principle of image processing, the image processing is performed by constituting the 3×3 mask.
Since the binarization method needs to have a band memory for storing and controlling the scanned document per unit of band for image-processing the pixel of the scanned document, it causes an increase in the cost of the multifunctional machine.
In addition, in the case of using a 3×3 mask for one band, since no data is contained in the end part of the band and in the beginning part of the next band, a boundary between the two bands is formed.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to reduce the cost of a multifunctional machine by reducing the amount of band memory required in an image processing of scanned data using a 3×3 mask.
It is another object of the present invention to prevent a boundary from being formed between each band.
According to one aspect of the present invention, an image processing apparatus for binarizing an image scanned by a scanner which performs a shuttle movement per unit of slice and scans a band, includes: a scanner for scanning pixels of a slice from a document; a processor for binarizing each pixel of the scanned slice using a mask; a first memory for storing processing results of error values generated during binarization of each final pixel of a plurality of slices of the band as binarized by the processor; and a second memory for storing processing results of error values generated during binarization of each pixel of the scanned slice as binarized by the processor. When binarizing each first pixel of a plurality of slices of the next band, the processor scans processing results of the error values of final pixels of a plurality of slices of the previous band, stored in the first memory, and binarizes the value. Afterwards, the processor scans the second memory and binarizes the next pixels.
According to another aspect of the present invention, after scanning pixels of one slice from the document, each of the pixels of the scanned slice is binarized using the mask. Processing results of the error values generated during binarizing of the final pixels of a plurality of slices of the band are stored in the first memory, and processing results of the error values generated during binarizing of each of the pixels of the scanned slice are stored in the second memory. When each of the first pixels of a plurality of slices in the next band are binarized, the processing result of the error values of the final pixels of a plurality of slices in the previous band, stored in the first memory, is scanned and binarized.
Preferably, the mask has 2×3 pixels. When expressed by vertical and horizontal coordinate values, coordinate values of positions
1
,
2
,
3
and
4
are (2, 1), (1, 1), (1, 2) and (1, 3), respectively and a coordinate value of position of a pixel X to be binarized is (2, 2).
Preferably, a method for forming the mask includes the steps of: when binarizing the first pixel of the slice, shifting a value of the position
1
, scanning an error value of a final pixel of a slice in the previous band corresponding to the pixel X to be binarized from the first memory and inputting the value to the position
1
; shifting a value of the position
4
to the position
3
, scanning an error value of a pixel preceding the pixel X to be binarized from the second memory and inputting the error value to the position
4
; when a signal for scanning the value of pixel X to be binarized is received and the position
1
is not filled in, filling in the position
1
with a value of the pixel preceding the pixel X to be binarized in the same slice and acquiring a pixel to be binarized next; and when the position
1
is filled in, shifting the value of the position
4
to the position
3
and shifting the value of the position
3
to the position
2
, and inputting an error value of a pixel having a horizontal coordinate value larger by one (1) than the pixel X to be binarized from among the pixels of the previous slice to the position
4
.
REFERENCES:
patent: 5429441 (1995-07-01), Schulz et al.
patent: 5701135 (1997-12-01), Aratani et al.
patent: 5884015 (1999-03-01), Yanaka et al.
Brinich Stephen
Bushnell , Esq. Robert E.
Lee Thomas D.
Samsung Electronics Co,. Ltd.
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