JP2002232716A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader which can surely correct base color. SOLUTION: A comparison updating part 340 makes a comparison between the peak value (white) of (n+1)-th line and the peak value (gray) of n-th line. If the difference P is determined to be larger than a prescribed value S, the peak value (white) of the (n+1)-th line will not be stored in a peak value storage part 350. In other words, the peak value before the n-th line is maintained as it is in the peak value storage part 350. The comparison updating part 340 outputs a processing signal to a base color correction processor 320 in order to make the peak value (white) of the (n+1)-th line to be the same as the peak value (gray) of the n-th line. As a result, when reading gray base color as white, even if it reads any white part on a document, the peak value can never be that of white.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus typified by a copier and a facsimile apparatus with a copying function, and more particularly to an image reading apparatus characterized by an operation for correcting the ground color of a document. It is.

[0002]

2. Description of the Related Art In an image reading apparatus, image data on a document is read as multivalued data. In an image reading device (reading unit) such as a facsimile device,
A binarization process is performed based on the multi-value data. As a result, when the read image data on the document is recorded on the recording paper, the image data is recorded on the recording paper in black and white and monochrome.

In an image reading apparatus, when the background color of a document is not white, for example, when the image data of the read document is recorded on a recording paper even if the document has a ground color, Some have a so-called ground color correction function that adjusts and outputs image data on a read original so that is not recorded on recording paper. Here, the ground color correction function is a function that adjusts and outputs image data on a read original by assuming that the peak value in one line of image data is all white, in other words, that the ground color is white. Say. That is, for example, when a document with a gray background color is read, image data on the read document is adjusted and output so that the ground color gray becomes white.

[0004]

However, if the white color on the document is read during the reading so that the ground color gray becomes white, the peak value becomes a white value. For this reason, the ground gray, which has been output as white image data, is now output as gray (or black) image data. As a result, when the image data output from the image reading apparatus is recorded on recording paper, a part of the ground color is recorded as gray (or black).

The present invention has been made in view of such a problem, and an object of the present invention is to provide an image reading apparatus capable of performing ground color correction reliably.

[0006]

In order to achieve the above object, according to the first aspect of the present invention, a peak value detecting section for detecting a peak value of one line of image data, and a peak value detecting section for detecting the peak value are provided. The peak value storage unit that stores the detected peak value is compared with the peak value detected by the peak value detection unit and the peak value stored in the peak value storage unit. If the difference is equal to or greater than a predetermined value, A comparison update unit that updates the peak value stored in the peak value storage unit, and a ground color correction processing unit that corrects the ground color based on the peak value stored in the peak value storage unit.

According to a second aspect of the present invention, in the image reading apparatus according to the first aspect, a difference between the peak value detected by the peak value detecting section and the peak value stored in the peak value storing section is determined. If it is less than the value, the peak value stored in the peak value storage unit is maintained.

According to a third aspect of the present invention, in the image reading apparatus according to the first or second aspect, the ground color correction processing section includes a peak value stored in the peak value storage section and a limit of image data. The difference from the value is calculated, and the difference is added to the image data.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which an image reading apparatus according to the present invention is embodied in a reading section of a facsimile apparatus will be described below with reference to the drawings.

As shown in FIG. 1, a facsimile apparatus 1
Are MPU 10, ROM 20, RAM 30, reading unit 4
0, a recording unit 50, an operation unit 60, a display unit 70, an image memory 80, a codec 90, a modem 100, and an NCU (network control circuit) 110.
110 are connected to each other via a bus 120.

The MPU 10 controls each unit constituting the facsimile machine 1. The ROM 20 stores a program for controlling the facsimile machine 1. RAM30
Stores various information related to the facsimile machine 1.

The reading section 40 reads image data on a document and outputs one line of binary data. Further, the reading unit 40 includes a ground color correction unit 41 that corrects the ground color of the read document.

The recording unit 50 is composed of an electrophotographic printer, and receives the image data and the reading unit 4 in the copy operation.
The image data of the original read at 0 is recorded on the recording paper.

An operation unit 60 includes a facsimile / copy key 61 for setting a facsimile mode or a copy mode, and an abbreviated key 6 for registering abbreviated numbers or transmitting from abbreviated numbers.
2. One-touch key 63 for specifying a pre-registered FAX number by one-touch, numeric keypad (including * and # keys) 64 for inputting a telephone number or the number of copies, etc., start for starting a document reading operation Key 65
And other various operation keys. A display unit 70 such as an LCD displays various information such as an operation state of the facsimile machine 1.

The image memory 80 temporarily stores received image data and image data read by the reading section 40. The codec 90 encodes the image data read by the reading unit 40 using the MH, MR, MMR, or the like for transmission. The codec 90 decodes the received image data.

The modem 100 is based on ITU (International Telecommunication Union) -T Recommendation T.30. 30 based on a facsimile transmission control procedure according to V.30. 17, V.I. 27ter, V.A. Modulation of the transmission data and demodulation of the reception data according to 29 or the like. The NCU 110 has a function of controlling connection with the telephone line L, a function of transmitting a dial signal corresponding to a telephone number (including a FAX number) of the other party, and a function of detecting an incoming call.

Next, the configuration of the ground color correction section 41 will be described with reference to the block diagram shown in FIG. As shown in FIG. 2, a CCD (Charge Coupled Device) 200 of the reading unit 40 reads image data on a document line by line and outputs an analog image signal representing the density of the image. In this example, C
The CD 200 converts the analog image signal of the (n + 1) th line into A /
The signal is output to a D (analog / digital) converter 300. A
The / D converter 300 converts the analog image signal output from the CCD 200 of the reading unit 40 into digital image data (256 gradations). And the A / D converter 3
00 outputs the multivalued data of the (n + 1) th line converted into digital data to the multivalued memory 310 and the peak value detection unit 330. Note that the number of gradations is not limited to 256, but can be changed as appropriate such as 64, 128, and 512.

The multi-value memory 310 stores the multi-value data of the (n + 1) -th line converted into digital data. Also,
The multilevel memory 310 stores the multilevel data of the (n + 1) th line output from the A / D converter 300 and outputs the multilevel data of the nth line to the ground color correction processing unit 320.

The peak value detecting section 330 detects a peak value from the multivalued data of the (n + 1) th line converted into digital data. Then, the peak value detection unit 330 outputs the detected peak value of the (n + 1) th line to the comparison update unit 340 and the peak value storage unit 350.

The comparing / updating unit 340 includes a peak value detecting unit 33
The peak value of the (n + 1) th line output from 0 is compared with the peak value stored in the peak value storage unit 350.
When the peak value of the (n + 1) th line output from the peak value detection unit 330 is larger than the peak value stored in the peak value storage unit 350, the comparison update unit 340 outputs the peak value from the peak value detection unit 330. An update signal for causing the peak value storage unit 350 to store the peak value of the (n + 1) th line is output. Based on this update signal, the peak value storage unit 350 stores the new peak value updated by the comparison update unit 340, that is, the peak value of the (n + 1) th line output from the peak value detection unit 330. Further, the comparison update unit 340 outputs a processing signal for processing the n-line multi-value data for each pixel based on the updated peak value to the ground color correction processing unit 320. Ground color correction processing unit 320
Performs n-line multi-valued data processing for each pixel, and
Output to IFO 400.

Next, the configuration of the ground color correction processing section 320 will be described with reference to the block diagram shown in FIG. As shown in FIG. 3, when a value “255” indicating all white in 256 gradations and a peak value from the peak value storage unit 350 are input, the subtractor 500 indicates a value “255” indicating all white. The difference P between the peak value and the peak value is calculated. Then, the subtractor 500 outputs the difference P to the latch circuit 510.

The latch circuit 510 latches the difference P input from the subtractor 500 based on the processing signal from the comparing / updating unit 340, and outputs the difference P to the adder 520. The multilevel memory 310 stores the multilevel data of the (n + 1) th line and outputs the multilevel data of the nth line to the adder 520.

The adder 520 adds the n-line multi-value data from the multi-value memory 310 and the difference P latched by the latch circuit 510 based on the processing signal from the comparison / update unit 340. Then, the adder 520 outputs the added value to the latch circuit 530.

The latch circuit 530 latches the value added by the adder 520 based on the clock signal from the reading unit 40, and outputs the value to the FIFO 400. FIFO400
Is multi-valued by a binarization circuit (not shown) and output on the bus 120.

Next, the image data output when the original is read by the reading section 40 of the facsimile apparatus 1 thus configured will be described with reference to the explanatory diagram shown in FIG.

An original as shown in FIG.
And the start key 65 is operated, the originals are sequentially read in the sub-scanning direction. Then, when the n lines are read, image data indicated by a chain line in FIG. 4B is obtained. On the other hand, when the (n + 1) th line is read, white image data is obtained as indicated by a dotted line in FIG.

However, the peak value of the (n + 1) th line (white)
Is compared with the peak value (gray) of the n-th line by the comparison update unit 340, it is determined that the difference P is equal to or larger than the predetermined value S. Therefore, the peak value (white) of the n + 1 line is
It is not stored in the peak value storage section 350. In other words, the peak value storage unit 350 keeps the peak value before the nth line as it is. While reading the white color, the peak value before the nth line is maintained as it is. Further, the comparison updating unit 340 outputs a processing signal for converting the peak value (white) of the (n + 1) th line to the peak value (gray) of the nth line to the ground color correction processing unit 320. As a result, as shown by the one-dot chain line in FIG. 4C, the peak value (white) of the (n + 1) -th line is represented by n shown by the one-dot chain line in FIG.
It is the same as the peak value (gray) of the line.

Then, the ground color correction processing section 320 calculates a difference P between the peak value stored in the peak value storage section 350 and “255” indicating all white in 256 gradations by the subtractor 500. Further, the ground color correction processing unit 320 adds the difference P calculated by the subtractor 500 to the n-line multi-value data output from the multi-value memory 310 based on the processing signal from the comparison / update unit 340. 520 is added. as a result,
The ground color correction processing unit 320 outputs the same image data as when gray is read as white, as indicated by the solid line in FIG. 4C, even when reading n + 1 lines including white.

Therefore, even when the white color on the document is read while the background color gray is read to be white, the peak value does not become a white value. For this reason, the ground gray which has been output as white image data until now is not output as gray (or black) image data. As a result, even when the output image data is recorded on recording paper, a part of the ground color is not recorded as gray (or black).

As described above, according to the present embodiment, the following operations and effects can be obtained. (1) The peak value (white) of the (n + 1) th line and the peak value (gray) of the nth line are compared by the comparison update unit 340.
When it is determined that the difference P is equal to or greater than the predetermined value S, the peak value (white) of the (n + 1) th line is not stored in the peak value storage unit 350. In other words, the peak value storage unit 350 keeps the peak value before the nth line as it is. And while reading white,
The peak value before the nth line is maintained as it is. Also,
The comparison update unit 340 calculates the peak value of the (n + 1) th line (white).
Is output to the ground color correction processing unit 320 to make the peak value (gray) of the n line. As a result, n + 1
The peak value (white) of the line becomes the same as the peak value (gray) of the n-th line. Therefore, even when the white color on the document is read while the ground color gray is read as white, the peak value does not become a white value. As a result, even when the output image data is recorded on recording paper, a part of the ground color is not recorded as gray (or black). Therefore, the ground color correction can be reliably performed.

(2) The peak value of the (n + 1) th line (white) and the peak value of the nth line (gray) are compared by the comparison updating unit 340. When it is determined that the difference P is less than the predetermined value S, the peak value (white) of the (n + 1) th line is stored in the peak value storage unit 350. In other words, the peak value in the peak value storage unit 350 is updated. Therefore, when the difference P is less than the predetermined value S, the ground color correction is reliably performed in accordance with the change in shading, and the read image data on the original is faithfully output. That is, the same image as the original can be recorded on the recording paper.

(3) The subtracter 500 calculates the difference P between the peak value stored in the peak value storage section 350 and the limit value of the image data, that is, “255” indicating all white at 256 gradations. . In addition, the ground color correction processing unit 320, based on the processing signal from the comparison update unit 340,
Is subtracted from the multi-value data of n lines output from
Are added by the adder 520. As a result, even when the ground color correction processing unit 320 reads n + 1 lines including white, the same image data as when gray is read as white is output. Therefore, even if the white color on the original is read while the ground color gray is read as white, if the output image data is recorded on paper, No part is recorded as gray (or black).

The above embodiment can be modified and embodied as follows. In the above-described embodiment, the peak value of the n-th line is compared with the peak value of the n + 1-th line.
The configuration may be such that the peak value up to the nth line is compared with the peak value of the (n + 1) th line.

In the above-described embodiment, the ground color correction is performed on the image data on the original document read by the reading unit 40. Alternatively, for example, the image data transferred from a personal computer or the like via a network may be used. The above-described embodiment may be applied to the case where the ground color correction is performed on.

Further, technical ideas grasped from the above embodiment will be described below together with their effects. [1] A peak value detection unit that detects a peak value of one line of image data, a peak value storage unit that stores a peak value detected by the peak value detection unit, and a peak value detected by the peak value detection unit And a peak value stored in the peak value storage unit, and when the difference is equal to or more than a predetermined value, a comparison update unit that updates the peak value stored in the peak value storage unit; An image reading apparatus comprising: a ground color correction processing unit that corrects a ground color based on a processing signal from a computer. With this configuration, the ground color correction can be performed reliably.

[2] The image reading apparatus according to any one of [1] to [3] or [1],
An image reading apparatus comprising: a reading element that reads image data on a document for each line and outputs the read image data for each line. With this configuration, the ground color correction can be performed reliably.

[3] In the image reading apparatus according to any one of [1] to [3] and [1] or [2], the peak value storage section stores the peak value of a predetermined line. Reader. With this configuration, the ground color correction can be performed reliably.

[0038]

Since the present invention is configured as described above, it has the following effects. According to the invention described in any one of the first to third aspects, the ground color correction can be reliably performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a facsimile apparatus with a copying function.

FIG. 2 is a block diagram illustrating a configuration of a ground color correction unit.

FIG. 3 is a block diagram illustrating a configuration of a ground color correction processing unit.

FIG. 4A is an explanatory view showing a document whose background color is gray. (B) Explanatory drawing which shows the image data of n line. (C) Explanatory drawing which shows the image data of the (n + 1) th line.

[Explanation of symbols]

Reference numeral 40: a reading unit as an image reading device; 41, a ground color correction unit; 320, a ground color correction processing unit; 330, a peak value detection unit; 340, a comparison update unit;

Claims (3)

[Claims] 1. A peak value detecting section for detecting a peak value of one line of image data, a peak value storing section for storing a peak value detected by the peak value detecting section, and a peak value detecting section for detecting a peak value detected by the peak value detecting section. Compare the peak value with the peak value stored in the peak value storage unit, and when the difference is equal to or greater than a predetermined value,
An image reading apparatus comprising: a comparison updating unit that updates a peak value stored in a peak value storage unit; and a ground color correction processing unit that performs ground color correction based on the peak value stored in the peak value storage unit. 2. The image reading apparatus according to claim 1, wherein a difference between the peak value detected by the peak value detection unit and the peak value stored in the peak value storage unit is smaller than a predetermined value. An image reading device that maintains a peak value stored in a value storage unit. 3. The image reading device according to claim 1, wherein the ground color correction processing unit calculates a difference between the peak value stored in the peak value storage unit and a limit value of the image data. And an image reading device for adding the difference to the image data.