JPS60236570A - Picture reading correction method - Google Patents

Abstract

PURPOSE:To obtain accurate picture data regardless of the fluctuation of the effective light emitting quantity of a light source itself, by using a value obtained by dividing the data obtained from a photosensor by the direct effective light emitting quantity of the light source as the picture data. CONSTITUTION:An original table 11 is shifted in a fixed direction by a subscan motor 12 which is revolved intermittently. While three light source lamps 6R, 6G and 6B are set on the back side of the table 11 in response to three colors R, G and B respectively. The signal C fed from a control photosensor 8 is stored once to a capacitor 41 in a light quantity circuit 40, then supplied to a sampling holder 43 by a sampling signal PS supplied from a timing signal generating circuit 15 via a switch 42. The holder 43 holds the input value until the next sampling signal PS is supplied, and at the same time supplies the signals, i.e., the correction signals C (CR, CG and CB) to a light quantity correction divider 21 synchronously with signals R, G and B. Then the divider 21 supplies the values obtained by dividing signals R, G and B by their correction signals CR, CG and CB respectively to an A/D conversion preprocessing circuit 19 as the picture data of R, G and B.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for reading and correcting image data using a line-type photosensor, and in particular, the present invention relates to a method for reading and correcting image data using a line-type photosensor. The present invention relates to a method for correcting read image data that allows accurate reading of image data.

(Prior art) In recent years, line photosensors (e.g. CCD photosensors)
With the increasing density of images, it has become possible to obtain highly accurate two-dimensional image data. The basic method is to use a lens 8 to form an image of the light transmitted through the original 1 or the light reflected by the original 1 on the light-receiving surface of the line-type photosensor 2, as shown in FIG. By sequentially changing the relative position of the photosensor and the document perpendicular to the longitudinal direction of the photosensor, images of required portions of the document are sequentially scanned by the photosensor and photoelectrically converted.

Furthermore, in order to record a color image, it is necessary to obtain image data of R (red), G (green), and B (blue).
Conventionally, there have been several methods for obtaining G and B data, as described below.

One of them is RoG, H on the front of one photo sensor.
Arrange a filter corresponding to one of the colors,
Scanning all the necessary parts of the document is repeated eight times to obtain image data for each color, and after the image data is temporarily stored in a memory, it is read out periodically.

In addition, as shown in FIG. 5(a), the dichroic filter 5
, 5 or R using a half mirror and color separation filter.
, G, and H, and the line-type photosensors 2R and 2G transmit the respective color lights.

There is also a method in which the color signals of 8 colors are inputted to 2B and simultaneously obtained from each line sensor.

Still another method is to arrange eight photosensors 2R, 2G, and 2B in parallel on the same plane, and arrange a color separation filter corresponding to each color in front of each sensor, as shown in FIG. 5(b). There is also a method in which separated color light obtained through the color separation filter is made to enter each photosensor.

Furthermore, the document is moved intermittently in a certain direction using a device as shown in FIG. are R, G, when the document 1 that moves intermittently is stationary.
Filters 5R and 5G corresponding to the eight colors are time-divisionally replaced in the order of B.

5B (for example, Japanese Patent Application Laid-Open No. 56-58i370)
(No. Publication) is also available.

In addition, a device as shown in FIG. 7 is used to move the document intermittently in a fixed direction, and
Light source lamp 6R corresponding to color.

A method of blinking 6, G, and 6B in a time-divisional manner (for example, Japanese Patent Application Laid-Open No. 56-169472, Japanese Patent Application Laid-open No. 58-212)
No. 255) is also available.

A method of collecting data for one pixel of a CCD sensor in advance and correcting it (for example, Japanese Patent Application No. 59-85886)
There is also. However, it does not respond to momentary changes in the amount of light.

(Problems to be Solved by the Invention) However, in any of the above methods, the amount of light emitted from the light source lamp may change over time due to factors such as changes in external voltage. Furthermore, when using filters or light source lamps for R, G, and 88 colors, the effective light emission amounts of each color before and after a certain period do not exactly match each other. Furthermore, in the above method of blinking the light source, even if the light emission time of one lamp is the same each time, the light emission intensity may not necessarily be the same due to various external and internal factors. It is difficult to make the amount of light emission the same.

This invention was proposed in view of the above-mentioned conventional difficulties, and its first purpose is to provide a method for blinking a light source that is accurate and does not depend on changes in the effective amount of light emitted each time the light source is turned on. The purpose of this invention is to provide a method that can obtain accurate image data. At the same time, it is an object of the present invention to provide a method capable of correcting fluctuations in the amount of light emitted over time and, when using document illumination light of a plurality of colors, the difference in the effective amount of light emitted between each color light.

(Means for Solving the Problem) The feature of the present invention is that the photoelectricity received by the line type photosensor is divided by the amount of light emitted from each light source lamp. In other words, using a control photosensor that directly receives the light from the light source lamp, the control photosensor detects the amount of light received by the control photosensor at the same time as the line-type photosensor. The amount of light received is divided by the amount of light received by the control photosensor.

(Example) and (effect) A more detailed explanation will be given below based on the drawings.

FIG. 2 is a block diagram showing an example of an apparatus for carrying out the present invention, and FIG. 2 (aXb) shows an example of its timing chart.

The document table 11 is moved in a fixed direction by a sub-scanning motor 12 which rotates intermittently in response to a sub-scanning drive signal Pm output from a sub-scanning control circuit 14. Eight light source lamps 6R, 6G, and 6B corresponding to each color of R, G, and B are arranged on the back side of the document table 11, and these eight light source lamps are output from the light source control circuit 16. The light source drive signals P7 (FIR, PIG, PIB) corresponding to the lamps 6R, 6G, and 6B sequentially blink while the original table 11 is stationary. When the light source lamp 6B is turned off, the motor 12 is rotated by the sub-scanning drive signal Pm to move the document table in a fixed direction (sub-scanning direction) by the width of one main-scanning line. On the other hand, after the light of each color irradiated onto the original as described above passes through the original A, an image is formed on the light receiving surface of the CCD line photosensor 2 via an optical device 80 such as a lens. Charges commensurate with the amount of transmitted light are accumulated in each element.

The CCD line photosensor 2 is driven as follows by the CCD drive signal PD output from the CCD drive circuit 17. In other words, the charge accumulation time is set between each pulse of the drive signal FD, for example, as shown in FIG. As shown in a), if the charge corresponding to the R signal is accumulated in a certain period TR, then in the next period TG, the light reception signal DR accumulated in the above TR period is output, and the charge corresponding to the G signal is accumulated, Furthermore, in the next period Tn, the light reception signal DG accumulated during the initial period of TG is outputted, and the charge corresponding to the B signal is accumulated.

R, G based on the charges accumulated as described above.

Light reception signal D (DR, Da, DB) corresponding to the amount of light received by B can
is input to the light amount correction divider 21 described below in a time-division manner.

A control photosensor 8 is disposed in front of the light sources 6R, 6G, and 6B, and a signal from the control photosensor 8 is input to a light amount monitor circuit 40 to
, 6G, and 6B are detected. It is desirable to use a control photosensor 8 whose spectral sensitivity characteristics are as close as possible to those of a CCD line photosensor.

That is, the light amount monitor circuit 40 is basically configured as shown in FIG. The sampling signal Pg input from the sampling holder 4
8 is input. The sampling holder 48 holds the input value until the next sampling signal Ps is input, and also outputs that signal, that is, the correction signal c (cR).

CG, CB) are input to a light amount correction divider 21, which will be described later, in synchronization with the input of the R, G, and B signals.

The analog switch 42 normally connects the capacitor 41
However, after the sampling signal PS is output, the reset signal P output from the timing signal generation circuit 15 is connected to the sampling holder 48.
The capacitor 41 is once grounded by r, and the charge remaining in the capacitor 41 is discharged. Light amount correction divider 21
are the values obtained by dividing the R, G, and B signals input as described above by the respective correction signals CR, C/G, and CB.
.

It is input to the preprocessing circuit 19 as image data of B.

This preprocessing circuit 19 is equipped with an AD converter, and performs AD conversion on the input R, G, B image data as described above, and further performs color correction and gradation correction as necessary. Buffer memory 20 for each color signal via selector 22
It is temporarily stored in R, 20G, and 20B, and then input to the image processing circuit 81.

This circuit is basically controlled as described above.

However, in such an apparatus, it is necessary to prevent the R, G, and B image data from being mixed with each other. Therefore, in the control method shown in FIG. 2(a), each light source 6R, 6G, 6
B is turned on and off. Also, Figure 2 (b
In the control method shown in ), a waste time E is provided before (after) the integration period for each color of RlG and B, and each light source lamp 6R
, 6G, and 6B are turned on at a discard time E before the integration period for each color of R9G and B, and are turned off at a discard time E after the integration period.

Therefore, the image data DE obtained at the waste time E contains two color signals, but this signal is not used.

The light amount correction divider 2 performs control that takes into consideration the characteristics of the control photosensor 8 so that the white balance of the RGB output signals is obtained.
Needless to say, it should be done in the first place.

These two embodiments can be applied to the case of the white light source shown in FIG. 4.6.6, and can also be applied to the case where the entire surface scan is performed sequentially for each color.

(Effects) As explained above, in this invention, the value obtained by dividing the data obtained from the line photosensor by the direct effective light emission amount of the light source is used as image data, so it is possible to avoid fluctuations in the effective light emission amount of the light source itself. It has the effect of being able to obtain accurate image data without being influenced by the image data.Especially, in the method of obtaining each color signal of R, G, and B in a time-sharing manner by blinking the R, G, and B light sources, each time It is possible to correct changes in the light emission intensity of different light sources each time the light source is turned on.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an example of an apparatus for carrying out this invention;
The figure is a timing chart of the device shown in Fig. 1, Fig. 8 is a circuit diagram showing the light amount motor used in the device shown in Fig. 1 in more detail, and Fig. '4 is a two-dimensional A diagram of the principle when obtaining image data. Figure 6 is a schematic diagram of an example of obtaining two-dimensional color image data using a line type photosensor. Figures 6 and 7 are a diagram of obtaining color image data. It is a schematic diagram showing another example. In the figure, 2... COD line photosensor, 6... Light source lamp, 8... Control photosensor,
11... Original table, 17... CCD drive circuit,
21... Light amount correction divider, 80... Lens, 40...
...Light level monitor circuit, A...Document. Figure 5 (a) (b) Figure 6 Figure 7

Claims (3)

[Claims] (1) By sequentially changing the relative position of the line type photosensor and the original in a direction perpendicular to the longitudinal direction of the photosensor, and photoelectrically converting the light from the light source obtained through the original using the photosensor. In an image scanning device that obtains two-dimensional image data, an image reading correction characterized in that a value obtained by dividing the effective amount of light received by the line-type photosensor by the amount of light emitted from a light source during the same period is used as image data. Method. (2) The light of the light source that illuminates the original is colored light, and the colored light obtained through the original is made to sequentially enter a line-type photosensor in a time-sharing manner. Image reading correction method. (3) The image reading correction method according to claim 2, wherein a plurality of light source lamps correspond to a plurality of specific colors characterized by light from the light source.