JPH11136470A - Image read method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To read images without performing mechanical scanning by two- dimensionally reading the image of an original by a two-dimensional charge coupled device(CCD) and outputting image data from the two-dimensional charge coupled device for respective lines. SOLUTION: By an image forming lens 12 such as a zoom lens or the like constituted of plural lenses, the image of the original 10 for read present on a main plane 13 is formed on the two-dimensional CCD 11 arranged on an image forming surface 14 and read. Then, image information for one page of the original 10 read by the two-dimensional CCD 11 is scanned line by line and stored in a memory. Thus, since the need of original carriage/the movement of a mirror carriage is eliminated, a mechanism part is simplified and image quality degradation by original carrying irregularity is eliminated. Also, since scanning time for one page is not controlled by a mechanism system, acceleration is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading method for reading an original.

[0002]

2. Description of the Related Art Conventionally, when a two-dimensional document is read by a facsimile machine or the like, a line sensor is used to move the document in the sub-scanning direction and read one line at a time. A method of reading one line at a time by moving in the sub-scanning direction has been used.

[0003]

However, reading an original using a line sensor requires mechanical sub-scanning, and a mechanism for that purpose is necessary. , There is a problem that image quality is deteriorated.

It is an object of the present invention to solve the above-mentioned problems and to provide an image reading method which can read an image without performing mechanical scanning and can easily perform shading correction.

[0005]

According to a first aspect of the present invention, an image of an original is two-dimensionally read by a two-dimensional charge-coupled device (hereinafter referred to as a CCD). This is an image reading method in which image data is output for each line.

According to a second aspect of the present invention, when shading correction of a two-dimensional CCD is performed, pixel outputs at predetermined points in the row and column directions in a shading image are stored, and pixels in an area surrounded by these predetermined points are determined. With the pixel output value of each predetermined point,
2. The image reading method according to claim 1, wherein shading data is obtained by three-dimensionally interpolating.

According to a third aspect of the present invention, there is provided the image reading method according to the first aspect, wherein the document is illuminated by a plurality of light sources or a ring or arc-shaped light source.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

In FIG. 1, reference numeral 10 denotes an original for reading,
11 is a two-dimensional CCD, 12 is an imaging lens such as a zoom lens composed of a plurality of lenses L, and the image of the original 10 on the main plane 13 is arranged on the imaging surface 14 through the imaging lens 12. The image is read on the formed two-dimensional CCD 11.

FIG. 2 shows an image reading circuit 20 for scanning image information of one page of the FAX document 10.

First, in the two-dimensional CCD 11, an infinite number of photodiodes are arranged in a column direction in a row direction, and each photodiode receives light and accumulates a charge corresponding to the amount of received light. They are output sequentially. The two-dimensional CCD 11 is an image processing IC 1
In the control 16 of 5, the column output of the line is an analog signal in units of rows (lines), and the A /
The data is input to a D converter 17 and is digitized and binarized.
9 is stored.

As described above, the image information for one page of the document is read by the two-dimensional CCD 11, and this is scanned line by line and stored in the memory 19, so that the document conveyance / the movement of the mirror carriage is required as in the conventional case. Since there is no document, the mechanism can be simplified, and there is no deterioration in image quality due to unevenness in document conveyance. Further, since the scan time for one page is not affected by the mechanical system, the speed can be increased.

When the image information of one page is read by the two-dimensional CCD 11, the light receiving amount tends to vary between the center and the periphery due to the image forming characteristics of the image forming lens 12. Therefore, as shown in FIG. Illuminate the entire surface uniformly.

FIG. 3A shows a case in which a plurality of incandescent lamps 21 are used as light sources, and the incandescent lamps 21 are arranged symmetrically with respect to the optical axis so as to illuminate the document 10 uniformly.

FIG. 3B shows a bar-shaped fluorescent lamp 22 arranged on both lower sides of the original 10, and FIG. 3C shows a ring-shaped or arc-shaped fluorescent lamp 23 arranged below the original 10. Thus, the original 10 is uniformly illuminated.

By irradiating the document 10 with light in multiple directions instead of one direction, uniform irradiation can be performed.

Next, the shading correction will be described.

First, in the shading correction using a conventional line sensor, as shown in FIG. 5, it is assumed that there is actual data R of the light reception amount of a pixel row (for example, 2,048 pixels) of the line sensor. The variation of the pixel row of the actual data R is sampled, for example, every 16 pixels, and each sampled data is linearly interpolated two-dimensionally to obtain shading data D of the pixel row. age,
Assuming that the shading data (corresponding to the pixel light amount) is y, for example, the equation of a straight line connecting x = 16 and x = 32 is f
(X) = ax + b, and a and b are obtained from sampling values y16 and y32 of x = 16 and x = 32.

Thus, the shading waveform at x = 24 is reproduced as f (24) = 24 · a + b, and y
24 data are required.

Accordingly, the shading data D of all the pixel rows can be obtained by linear interpolation, and a threshold value for binarization may be set with this data.

However, when the two-dimensional CCD 11 is used, the shading data D cannot be obtained by the two-dimensional interpolation described above.

Therefore, as shown in FIG.
And a predetermined point P (16n) in the row direction (y) every 16 pixels, for example.
, 16m) (where n and m are integers), sample the value Dp of the predetermined point P, obtain the shading data D in the column direction (x) by linear interpolation from the value, and obtain the shading data Dp. The shading waveform is reproduced by three-dimensionally interpolating the pixel values in the area A within the predetermined point P.

That is, data Dp for each predetermined point P is sampled from the actual data R in the column direction (x) on the same row (y) to obtain shading data D, and then, from the shading data D adjacent in the row direction, For example, y
= 32 and y = 40 in the column direction at predetermined points PAs (x = 40, y
= 32), PBs (x = 40, y = 40), PAt (x = 4
8, y = 32) and three-dimensional interpolation of any pixel in PBt (x = 48, y = 40), x = 4 of y = 36 in the figure.
When three-dimensionally interpolating 0 to 48, the predetermined points PAs, PBs
DCs is obtained by linear interpolation in the y-direction from the data DAs and DBs of the data, and at the same time, Ds is obtained from the data DAt and
Ct is obtained by linear interpolation in the y direction, and Dc obtained by this interpolation is obtained.
Shading data Dx of any pixel of x = 40 to 48 can be obtained by linear interpolation of s and DCt.

[0024]

In summary, according to the present invention, two-dimensional C
By reading image information for one page of a document from a CD, scanning this one line at a time, and storing it in memory, there is no need to move the document carriage / mirror carriage as in the past, so the mechanism is simplified. The image quality is not degraded due to the unevenness of document conveyance. Further, since the scan time for one page is not affected by the mechanical system, the speed can be increased.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a reading circuit of FIG. 1;

FIG. 3 is a diagram showing another embodiment of the present invention.

FIG. 4 is an explanatory diagram when performing three-dimensional shading correction in the present invention.

FIG. 5 is a diagram illustrating a conventional shading correction.

[Explanation of symbols]

 10 Document 11 Two-dimensional CCD 12 Imaging lens

Claims (3)

[Claims] 2. An image reading method, comprising: reading an image of a document two-dimensionally with a two-dimensional CCD; and outputting image data from the two-dimensional CCD for each line. 2. When shading correction of a two-dimensional CCD is performed, a pixel output of a predetermined point in a row and column direction in a shading image is stored, and a pixel in an area surrounded by these predetermined points is replaced with a pixel of each predetermined point. 2. The image reading method according to claim 1, wherein shading data is obtained by three-dimensionally interpolating the output value. 3. The image reading method according to claim 1, wherein the document is illuminated with a plurality of light sources or a ring or arc-shaped light source.