JPH0490678A - Picture reader - Google Patents

Abstract

PURPOSE:To prevent an original edge part, which base color is colorless, from being erroneously decided by extracting an optical image in a specified wavelength area from an optical image to be obtained by scanning a hue judging area, which is set narrower than the effective picture area of an original only by a prescribed component, and judging the hue based on the luminance of this extracted optical image. CONSTITUTION:An optical scanning part S is composed of a light emitting body 1, reflecting mirror 4, lens 5 and CCD image sensor 6. The hue judging area is set narrower than the effective picture area of the original only by the component decided in advance, the set hue judging area is scanned by this scanning part S, the optical image in the specified wavelength area is extracted from the optical image to be obtained by scanning with the scanning part S, and the hue is judged based on the luminance of the extracted optical image. Thus, there is no problem that the area of a marker, etc., using a chromatic color is not correctly read since the edge part of the original is judged as the chromatic color although it is an achromatic color.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image reading device that recognizes color information on a document and performs various processes.

[Prior Art] Various methods have been proposed in the past for recognizing colors on a document and performing image processing based on the color information. For example, image processing such as specifying an area on a document using a chromatic marker or the like and performing different processing (masking, trimming) within that area from other areas is performed. In this case, a configuration is adopted in which the color information on the document is read with an image sensor, etc., a signal is used to determine whether it is an achromatic color or a chromatic color, the continuity of a certain chromatic color information is determined, and that area is extracted. ing.

Chromatic colors are determined by dividing the light from the document image read by the image sensor into specific wavelength ranges using color filters, etc. according to the hue of the judgment color, and then making decisions according to the brightness signal level of the image sensor that receives the light. .

This can be achieved by using multiple image sensors depending on the number of divided specific wavelength ranges, or by using image sensors that are sensitive to multiple wavelength ranges as a single unit to create an image sensor that corresponds to each wavelength range. Colors are often determined by comparing and calculating luminance signals.

However, the optical images on the image sensor corresponding to each wavelength range are shifted, or the achromatic area on the document is smaller than the minimum width of the resolution of the image sensor, and the adjacent pixels of the image sensor are affected by the light. When the images straddle each other, the level of the luminance signal in each wavelength range is different from that of an achromatic color, and may be determined to be a chromatic color.

As a method to prevent such misjudgment, it is necessary to select a color in an area where there are few different chromatic colors (1 in terms of number of pixels).
(approximately 2 pixels) There is a method in which adjacent patterns are made achromatic, and chromatic colors in a small area adjacent to the achromatic area are made achromatic.

[Problem to be solved by the invention] However, the edge portion of the document placed on the document table is
If it coincides with the boundary of the effective image area of the CD image sensor reading range, it is determined that it is separated into two chromatic colors on the CCD image sensor, similar to an achromatic thin line. C.O.
In the pixel data read by the D image sensor, if there is a discrepancy between the pixel data read for hue A and the pixel data read for hue B, as shown in FIG. Although the brightness levels are the same, pixels S and C with a shift are judged differently. For this reason, even though it is achromatic, Figure 6 (
The pixel 19 shown in a) is judged as if hue A and hue B exist adjacently, and as shown in FIG. 6(b), the chromatic color information (chromatic color pixel) of one of the adjacent ones is outside the valid image area, and the other adjacent chromatic color information (chromatic color pixel) is determined to be within the valid image area, that is, as independent color information, and pixel 19 within the valid image area is treated as an achromatic color. Not corrected. Therefore, even though the edges of the document are achromatic, they are determined to be chromatic, and there is a problem in that correct areas such as markers using chromatic colors cannot be read.

An object of the present invention is to provide an image reading device that solves the above problems.

[Means for Solving the Problems] In order to achieve such an object, the present invention provides a setting means for setting a hue determination area narrower by a predetermined amount than an effective image area of a document, and a scanning means for scanning a hue judgment region obtained by scanning, an extraction means for extracting a light image in a specific wavelength range from a light image obtained by scanning with the scanning means, and a method based on the brightness of the light image extracted by the extraction means. The present invention is characterized by comprising a hue determining means for determining hue.

The present invention also provides a continuity determining means for determining the continuity of the hue determined by the hue determining means, and an area surrounded by the hue when there is continuity as a result of the determination by the continuity determining means. The image forming apparatus is characterized by comprising an area extracting means for extracting a specific color area smaller than the effective image area of the document.

[Function] In the present invention, the setting means sets a hue judgment area narrower by a predetermined amount than the effective image area of the document, the scanning means scans the hue judgment area set by the setting means,
The extraction means extracts an optical image in a specific wavelength range from the optical image obtained by scanning with the scanning means, and the hue determination means determines the hue based on the brightness of the optical image extracted by the extraction means.

Further, in the present invention, the continuity of the hue determined by the hue determination means is determined by the continuity determination means, and if the continuity determination means determines that the hue is continuous, the area surrounded by the hue is The extraction means extracts a specific color area smaller than the effective image area of the document.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

1 and 2 show one embodiment of the invention.

In FIG. 1, S is an optical scanning section, a light emitter 19, a reflecting mirror 4. It is composed of a lens 5 and a CCD image sensor 6. The light emitter 1 is for illuminating the original.

A reflecting mirror 4 guides light from the original to a lens 5.

The lens 5 forms a light image on the CCD image sensor 6. The CCD image sensor 6 is composed of two sensors each having sensitivity to two specific wavelength ranges.

Reference numeral 77 is a reflective photosensor, which is installed in three locations.
For example, A3. B4. A4. This detects the size of a standard document such as A4 landscape.

In FIG. 2, 6 indicates the same part as in FIG. 1. 7 is an amplification/sample hold circuit, and CCD image sensor 6
It amplifies and samples and holds signals corresponding to the hue of the original. 8 is an A/D converter that converts the analog signal from the amplification/sample hold circuit 7 into a digital signal. 9 is a shading correction circuit that performs shading correction. 10 is a hue determination processing circuit that determines the hue based on the image signal after shading correction. Hue judgment processing circuit lO
An image signal 17 and a hue determination signal 16 are outputted from. Image signal 17 is within the area of the effective image area signal (fourth
Image processing is performed in Figure B) and output to the next stage image processing circuit. The hue determination signal 16 is determined within the area of the hue determination region signal (FIG. 4B). Reference numeral 11 denotes a hue determination correction processing circuit, which corrects the hue determination signal 16 from the hue determination processing circuit IO. Reference numeral 12 denotes a specific color area extraction processing circuit, which extracts and processes a specific color area. 14a is an effective image area section signal generation circuit, based on the reference pulse from the timing generation circuit 13,
This generates an effective image area signal based on the size of the original of the read image data.

Reference numeral 14b denotes a hue determination area section signal generation circuit, which generates an area signal for performing hue determination based on the aforementioned effective image area. A timing generation circuit 13 generates timing signals for each circuit. 15 is CPL
It is I.

FIG. 3 shows a second illustrated effective image area section signal generation circuit 14a.
The configuration is shown below.

The effective image area generation circuit 14a counts the number of pixels in the main scanning direction, which is data for one line read from the CCD image sensor 6, based on the readout clock of the CCD image sensor 6, and generates an effective image area signal in the main scanning direction. generate. In addition, in the sub-scanning direction, one of the CCD image sensors 6 is
By counting the number of shift pulses for a line, an effective image area signal in the sub-scanning direction is generated. At this time, a comparator 24 compares the output value of each counter circuit 22 with the values of registers 25a and 25b that set the area.
a.

24b makes it possible to generate a section signal.

On the other hand, the hue determination area generation circuit 14b generates hue determination areas in the main scanning direction and the sub-scanning direction by comparing the output value of the counter in the effective image area generation circuit 14a with another register value that sets the area. It becomes possible to do so. At this time, if the value of the register, which is the comparison value, is set to be smaller than the above-mentioned effective pixel area, an area signal as shown in FIG. 4 can be generated. Therefore, the image signal is processed within the above-mentioned effective image area (B), and the hue correction process and specific color area extraction process in the hue determination process 9 are performed in the hue determination area (A). The erroneous determination of achromatic color at the pixel 20 within the hue determination area shown in FIG. 5(a) is corrected by the hue determination correction processing circuit 1, resulting in the result as shown in FIG. 5(b). In addition, in the edge portion 19 of the manuscript,
Since it is outside the hue determination area, the color is not determined and is processed as an achromatic color (see FIG. 5(b)).

Next, an example of detecting standard-sized originals having different sizes to be read will be described.

A reflective photosensor 77 detects the presence or absence of paper at that position, and a combination of three sensors detects, for example, an A3
．． B4. A4. It is possible to detect the size of a standard document such as A4 landscape. By recognizing this detection result by the CPU and changing the setting values of the registers 25a and 25b when generating the area signal described above according to the size of the scanned original, the effective image area can be determined even for originals of different sizes. In addition, the hue determination area can be changed, and problems due to differences in the size of the original to be read do not occur.

Note that a CCD for image reading is used instead of the photosensor 77.
The recognition may be performed by performing a blisscan or the like before scanning for image reading.

[Effects of the Invention] As described above, according to the present invention, with the above configuration, it is possible to prevent erroneous determination of the edge portion of a document whose background color is an achromatic color.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the structure of an embodiment of the present invention, FIG. 2 is a block diagram showing the structure of an embodiment of the invention, and FIG. 3 is the effective image area section signal generation circuit 14a shown in the second diagram.
FIG. 4 is a block diagram showing the configuration of the system; FIG. 4 is a diagram showing the size relationship of the hue determination/specific color area extraction area, effective image area, and sensor reading area; FIG. FIG. 6 is an explanatory diagram illustrating image processing by a conventional method. FIG. 7 is an explanatory diagram illustrating pixel shift. 6... CCD unit, 10... Hue judgment processing circuit, 11... Hue judgment correction processing circuit, 12... Specific color area extraction processing circuit, 14a... Valid image area section signal generation circuit, 14b . . . Hue determination area section signal generation circuit, 15 . . . CPU. ...Original illumination lamp, ...Original platen cover...Original platen glass, °°°ζ lens, Fig. Private production level 1 [A color cleaning bell] [B color brightness level] (a and CB level brightness level) (b> (Ct, 6.c, d I, IM, f2. value + 211 degrees) indicating the bell) 7th vA

Claims (1)

[Scope of Claims] 1) Setting means for setting a hue judgment area narrower by a predetermined amount than the effective image area of the original; scanning means for scanning the hue judgment area set by the setting means; and the scanning means. The present invention is characterized by comprising an extraction means for extracting an optical image in a specific wavelength range from an optical image obtained by scanning by the extraction means, and a hue determination means for determining the hue based on the brightness of the optical image extracted by the extraction means. image reading device. 2) In claim 1, the setting means includes a detection means for detecting the size of the document, and an area changing means for reducing the size of the hue judgment region according to the size of the document detected by the detection means. An image reading device comprising: 3) In claim 1, a continuity determining means for determining the continuity of the hue determined by the hue determining means; and when the hue determined by the continuity determining means has continuity;
An image reading device comprising: area extracting means for extracting a specific color area smaller than an effective image area of the document from an area surrounded by the hue.