JPS6096076A - Device for correcting shading distortion - Google Patents

Device for correcting shading distortion

Info

Publication number
JPS6096076A
JPS6096076A JP58204031A JP20403183A JPS6096076A JP S6096076 A JPS6096076 A JP S6096076A JP 58204031 A JP58204031 A JP 58204031A JP 20403183 A JP20403183 A JP 20403183A JP S6096076 A JPS6096076 A JP S6096076A
Authority
JP
Japan
Prior art keywords
original
correction coefficient
white reference
scanner
scan signal
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP58204031A
Other languages
Japanese (ja)
Inventor
Mitsuo Togashi
富樫 光夫
Shinichi Sato
真一 佐藤
Toshiaki Watanabe
俊明 渡辺
Shiyoutoku Ooshima
大島 昇徳
Tatsu Nakamura
達 中村
Kazuyoshi Ariga
有賀 和義
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Panasonic System Solutions Japan Co Ltd
Panasonic Holdings Corp
Original Assignee
Matsushita Graphic Communication Systems Inc
Matsushita Electric Industrial Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Matsushita Graphic Communication Systems Inc, Matsushita Electric Industrial Co Ltd filed Critical Matsushita Graphic Communication Systems Inc
Priority to JP58204031A priority Critical patent/JPS6096076A/en
Publication of JPS6096076A publication Critical patent/JPS6096076A/en
Pending legal-status Critical Current

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  • Image Input (AREA)
  • Facsimile Image Signal Circuits (AREA)

Abstract

PURPOSE:To execute shading correction, which is easy to be realized as a comparatively inexpensive integrated circuit and has high accuracy and stability by adopting an MOS type A/D convertor using a small chopper comparator of offset voltage as circuit constitution. CONSTITUTION:Prior to reading an original, reading and scanning of a white reference plate 5 is executed by a scanner 2 and a white reference scan signal is inputted in an A/D convertor 9, a correction coefficient M is read out from an ROM10 address which is designated by the white reference scan signal changed into a digital, and wrote in an address which is in correspondence to a picture element of an RAM11. Then an original 4 is transferred to a read position, and an original scan signal is inputted in a device 1 for correcting shading strain from the scanner 2. At this time, the RAM11 is operated in a read mode and outputs a correction coefficient by synchronizing with a read scan. An operator 12 performs multiplication of said correction coefficient and the original scan signal which is changed into digitals by the A/D convertor 9 and outputs the original picture information whose shading strain is corrected.

Description

【発明の詳細な説明】 産業上の利用分野 不発明は、ファクシミリ装置の原稿読取部等に用いられ
るシェーディング歪み補正装置に関する。
DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shading distortion correction device used in a document reading section of a facsimile machine.

従来例の構成とその問題点 ファクシミリ装置の原稿読取部等に用いられるスキャナ
によって原稿を走査して得られる信号(原稿走査信号と
称す)は、一般に、原稿照明光源の光量ムラ、光学系の
光量ムラ、イメージセンサの感度バラツキ等による歪み
(以下、これ等の歪みをシェーディング歪みと総称する
)を受けている。そこで、ファクシミリ装置の原稿読取
部等においては、スキャナの後段にシェーディング歪み
補正装置を置き、原稿走査信号のシェーディング歪みを
補正するようにしている。
Conventional configuration and its problems Signals obtained by scanning a document with a scanner used in the document reading section of a facsimile machine (referred to as a document scanning signal) are generally affected by uneven light intensity of the document illumination light source and light intensity of the optical system. It is subject to distortion due to unevenness, sensitivity variations in the image sensor, etc. (hereinafter, these distortions are collectively referred to as shading distortion). Therefore, in a document reading section of a facsimile machine, a shading distortion correction device is placed after the scanner to correct the shading distortion of the document scanning signal.

このようなシェーディング歪み補正装置は、スキャナか
ら入力されるアナログの原稿走査信号を、A/D変換器
によってディジタル信号に変換してから補正演算を実行
するように構成さ々)のが一般的である。しかし、この
ような従来の装置は、バイポーラ型のA/D変換器を採
用しているため、消費電力が大きく、コストも高く、集
積化が容易でないという問題があった。
Such shading distortion correction devices are generally configured to convert an analog document scanning signal input from a scanner into a digital signal using an A/D converter, and then execute correction calculations. be. However, since such conventional devices employ bipolar A/D converters, they have the problems of high power consumption, high cost, and difficulty in integration.

本発明は上記従来の問題点を解消するもので、比較的安
価な集積回路として実現容易で、高精度かつ安定なシェ
ーディング歪み補正が可能なシェーディング歪み補正装
置全提供することを目的とする。
The present invention solves the above-mentioned conventional problems, and aims to provide a complete shading distortion correction device that can be easily realized as a relatively inexpensive integrated circuit and that can perform highly accurate and stable shading distortion correction.

発明の構成 本発明は、従来装置の集積化全困難にしていたA/D変
換器をMOS化し、集積化を容易化するとともに、バイ
ポーラ型ム/D変換器を用いた場合に匹敵する十分な補
正精度を得られるように、オフセット電圧の小さなチョ
ッパ型比較器を用いた回路構成のMO8型A/D変換器
を採用することを主たる特徴とするものである。
Structure of the Invention The present invention converts the A/D converter, which had been difficult to integrate in conventional devices, into a MOS, making it easier to integrate, and at the same time achieving sufficient performance comparable to when using a bipolar MU/D converter. The main feature is that an MO8 type A/D converter with a circuit configuration using a chopper type comparator with a small offset voltage is used so as to obtain correction accuracy.

より詳細に述べれば、本発明にょ乙シェーディング歪み
補正装置は、チョッパ型比較器全用いた回路構成のMo
s型A/D変換器と、ROMと、RAMと、演算2gと
を有し、外部のスキャナから入力される白基準板走査信
1号を上記A / D変換器でディジタル化して上記R
OMにアドレス信号として入力することにより上記RO
Mよシ補正係数を出力させ、同補正係数を上記RAMに
記憶させておき、その後に上記スキャナから入力される
原稿走査信号を上記A/D変換器でディジタル化して上
記演算器に入力し、同時に上記RAMから上記補正係数
ヲ読み出して上記演算器に入力し、同演算器で上記原稿
走査信号と上記補正係数の演算を行うことにより、上記
原稿走査信号にシェーディング歪み補正を施す構成であ
る。
More specifically, the shading distortion correction device of the present invention has a circuit configuration using all chopper type comparators.
It has an s-type A/D converter, ROM, RAM, and calculation 2g, and the white reference plate scanning signal 1 inputted from an external scanner is digitized by the above A/D converter, and the above R
By inputting the address signal to OM, the above RO
outputting an M direction correction coefficient, storing the same correction coefficient in the RAM, and then digitizing the original scanning signal input from the scanner with the A/D converter and inputting it to the arithmetic unit; At the same time, the correction coefficient is read from the RAM and input to the arithmetic unit, and the arithmetic unit calculates the original scanning signal and the correction coefficient, thereby correcting shading distortion on the original scanning signal.

実施例の説明 以下、図面を参照し本発明の実施例につき説明する。Description of examples Embodiments of the present invention will be described below with reference to the drawings.

図は本発明の一実施例によるシェーディング歪み補正装
置の5概略ブロック図であり、スキャナの概略構成も同
時に示している。この図において、1はシェーディング
歪み補正装置、2はスキャナである。
The figure is a schematic block diagram of a shading distortion correction device according to an embodiment of the present invention, and also shows a schematic configuration of a scanner. In this figure, 1 is a shading distortion correction device, and 2 is a scanner.

スキャナ1について説明すれば、3は原稿4または白基
準板5を照明するためのランプであシ、このランプ3に
よって照明された原稿4または白基準板5の画像は、レ
ンズ6を介してCCDイメージセンサ7の受光面に結像
され、CCDイメージセンサ7によりアナログ画信号(
原稿走査信号捷たは白基準板走査信号)に光電変換され
る。原稿4または白基準板5に対する読取走査の主走査
はCCDイメージセンサ7により行われ、副走査は原稿
移動により行われる(白基準板5に対する副走査は行わ
れないン。C,CDイメージセンサ7から出力されるア
ナログの白基準板走査信号または原稿走査信号は、増幅
器8によって増幅されたのち、シェーディング歪み補正
装置1に入力される。
To explain the scanner 1, numeral 3 is a lamp for illuminating an original 4 or a white reference plate 5, and an image of the original 4 or white reference plate 5 illuminated by this lamp 3 is sent to a CCD via a lens 6. An image is formed on the light receiving surface of the image sensor 7, and an analog image signal (
The signal is photoelectrically converted into an original scanning signal (original scanning signal or white reference plate scanning signal). Main scanning for reading the original 4 or white reference plate 5 is performed by the CCD image sensor 7, and sub-scanning is performed by moving the original (sub-scanning for the white reference plate 5 is not performed.C, CD image sensor 7 The analog white reference plate scanning signal or original scanning signal outputted from the shading distortion correction device 1 is amplified by the amplifier 8 and then inputted to the shading distortion correction device 1 .

シェーディング歪み補正装置1の構成を置明すれば、9
はチョッパ型比較器を用いた回路構成のMO8型A/D
変換器であり、スキャナ2から入力される白基準板走査
信号または原稿走査信号をディジタル倍量に変換する。
If the configuration of the shading distortion correction device 1 is explained, 9
is an MO8 type A/D with a circuit configuration using a chopper type comparator.
This converter converts the white reference plate scanning signal or original scanning signal input from the scanner 2 into a digital double signal.

10はROM、11はRAM、 12は演算器である。10 is a ROM, 11 is a RAM, and 12 is an arithmetic unit.

A/D変換器9の出力信号は、ROM10にアドレス信
号とじて入力され、また演算器12に一方のオペランド
データとして入力される。ROM10の出力信号(補正
係数)はRAM1tに書き込みデータとして入力され、
RAM11の出力信号(補正係数)は演算器12に他方
のオペランドデータとして入力される。
The output signal of the A/D converter 9 is input to the ROM 10 as an address signal, and is also input to the arithmetic unit 12 as one operand data. The output signal (correction coefficient) of ROM10 is inputted to RAM1t as write data,
The output signal (correction coefficient) of the RAM 11 is input to the arithmetic unit 12 as the other operand data.

次に動作を説明する。原稿読取に先だって、スキャナ2
により白基準板6の読取走査が行われ、白基準板走査信
号がA/D変換器9に入力される。
Next, the operation will be explained. Before reading the original, scanner 2
The white reference plate 6 is read and scanned, and a white reference plate scanning signal is input to the A/D converter 9.

A/D変換器9によってディジタル化された白基準板走
査信号で指定されるROM10のアドレスから、次の式
(1)で決まる補正係数Mが読み出され、RAM11の
画素対応のアドレスに書き込まれる。
A correction coefficient M determined by the following equation (1) is read from the address in the ROM 10 specified by the white reference plate scanning signal digitized by the A/D converter 9, and written to the address corresponding to the pixel in the RAM 11. .

Win x M/2n −C ・・・・・・・・・・・・・・ (1)ここでVin 
は白基準板走査信号の値、nは量子化ビット数、Cは定
数である。このCはシェーディング歪みの補正範囲の下
限値に相当する。
Win x M/2n -C ・・・・・・・・・・・・・・・ (1) Here, Vin
is the value of the white reference plate scanning signal, n is the number of quantization bits, and C is a constant. This C corresponds to the lower limit value of the shading distortion correction range.

このようにして画素毎の補正係数が順次求められ、RA
M11に格納されて行き、最終的に1ライン分の補正係
数がRAM11に格納される。白基準板走査信号はその
時点におけるスキャナ2の状態で決まるシェーディング
歪みを受けており、RAMt 1内の補正係数にそのシ
ェーディング歪みが反映している。
In this way, the correction coefficients for each pixel are sequentially determined, and the RA
The correction coefficients for one line are finally stored in the RAM 11. The white reference plate scanning signal is subjected to shading distortion determined by the state of the scanner 2 at that time, and the shading distortion is reflected in the correction coefficient in the RAM t1.

その後、原稿4が読取位置に搬送され、原稿4の読取走
査が開始し、スキャナ2から原稿走査信号がシェーディ
ング歪み補正装置1に入力される。
Thereafter, the original 4 is conveyed to the reading position, reading scanning of the original 4 is started, and an original scanning signal is input from the scanner 2 to the shading distortion correction device 1 .

この時は、RAM11は読出モードで動作し、読取走査
と同期して補正係数を出力する。この補正係数と、A/
D変換器9によってディジタル化された原稿走査信号と
の乗算が演算器12で実行され、シェーディング歪み補
正を施された原稿走査信号(原稿画情報)が演算器12
より出力される。
At this time, the RAM 11 operates in the read mode and outputs the correction coefficient in synchronization with the read scan. This correction coefficient and A/
Multiplication with the original scanning signal digitized by the D converter 9 is executed in the computing unit 12, and the original scanning signal (original image information) subjected to shading distortion correction is sent to the computing unit 12.
It is output from

一般にスキャナ2のシェーディング歪み特性は、ランプ
3の点灯直後は時間とともに相当大幅に変動する傾向が
あるが、RAM11内の補正係数は原稿読取の開始直前
における白基準板走査信号からめられたものであり、原
稿読取時のスキャナ2のシェーディング歪み特性を忠実
に反映している。従って、常に安定なシェーディング歪
み補正が為される。また、MO8型A/D変換器には、
直結型比較器を用いる回路構成のものと、チョッパ型比
較器を用いる回路構成のものがあり、前者は入力オフセ
ット電圧が一般にcsmV程度と大きく、5ビット以上
の量子化精度を得ることは困難であるが、後者は5ビッ
ト以上の高い量子化精度を容易に得られる。しかして、
上記A/D変換器9はチョッパ型比較器を用いた回路構
成のものであり、5ビット以上の量子化精度を得られる
ので、高精度の7エーデイング歪み補正が可能である。
In general, the shading distortion characteristics of the scanner 2 tend to fluctuate considerably over time immediately after the lamp 3 is turned on, but the correction coefficients in the RAM 11 are determined from the white reference plate scanning signal immediately before the start of document reading. , which faithfully reflects the shading distortion characteristics of the scanner 2 when reading a document. Therefore, stable shading distortion correction is always performed. In addition, the MO8 type A/D converter has
There are circuit configurations that use a direct-coupled comparator and circuit configurations that use a chopper-type comparator.The former has a large input offset voltage, generally around csmV, and it is difficult to obtain quantization accuracy of 5 bits or more. However, in the latter case, high quantization precision of 5 bits or more can be easily obtained. However,
The A/D converter 9 has a circuit configuration using a chopper type comparator, and can obtain a quantization accuracy of 5 bits or more, so that highly accurate 7-edding distortion correction is possible.

さらに、従来は消費電力の大きいバイポーラ型ム/D変
換器の存在が集積化の妨げにな−)ていたが、A/D変
換器9はMOS型であるから、本シェーディング歪み補
正装置1は全体またはRAM11以外の部分を一つの半
導体チップ上に容易に集積化できる。
Furthermore, in the past, the existence of a bipolar type MU/D converter with high power consumption was an obstacle to integration, but since the A/D converter 9 is a MOS type, the present shading distortion correction device 1 The entire structure or parts other than the RAM 11 can be easily integrated on one semiconductor chip.

発明の効果 上述のように本発明によれば、集積化に適し、かつ高い
量子化精度を得られるチョッパ型比較器構成のMO8型
A/D変換器を用いるので、集積化が容易で高精度の7
エーデイング歪み補正が可能なシェーディング歪み補正
装置を提供でき、また、原稿読取に先立って入力される
白基準板走査信号に基つきめて記憶した補正係数を補正
に用いるから、常に安定したシェーディング歪み補正が
可能となる等の効果を得られる。
Effects of the Invention As described above, according to the present invention, an MO8 type A/D converter with a chopper type comparator configuration that is suitable for integration and can obtain high quantization accuracy is used, so integration is easy and high precision is achieved. 7
It is possible to provide a shading distortion correction device capable of correcting aging distortion, and since the correction coefficients stored based on the white reference plate scanning signal input prior to reading the original are used for correction, stable shading distortion correction is always possible. Effects such as being made possible can be obtained.

【図面の簡単な説明】[Brief explanation of the drawing]

図は本発明の一実施例によるシェーディング歪み補正装
置を示す概略ブロック図である。 1・・・・シェーディング歪み補正装置、2・・・・・
スキャナ、3・・・・ランプ、4・・・・原稿、6・・
・・白基準板、6・・・・レンズ、7・・・・CODイ
メージセンサ、8・・・・・・増幅器、9・・・・・M
O3型A/D変換器、1o・・・・ROM、11・・・
・・RAM、12・・・・・演算器。
The figure is a schematic block diagram showing a shading distortion correction device according to an embodiment of the present invention. 1... Shading distortion correction device, 2...
Scanner, 3...Lamp, 4...Document, 6...
...White reference plate, 6...Lens, 7...COD image sensor, 8...Amplifier, 9...M
O3 type A/D converter, 1o...ROM, 11...
...RAM, 12... Arithmetic unit.

Claims (1)

【特許請求の範囲】[Claims] チョッパ型比較器を用いた回路構成のMO8型A/D変
換器と、ROMと、RAMと、演算器とを有し、外部の
スキャナから入力される白基準板走査信号を上記A/D
変換器でディジタル化して」1記ROMにアドレス信号
として入力することにより上記ROMよシ補正係数を出
力させ、同補正係Fl’f:上記RAMに記憶させてお
き、その後に上記スキャナから入力される原稿走査信号
を上記A/D変換器でディジタル化して上記演算器に入
力し、同時に上記RAMから上記補正係数を読み出して
」1記演算器に入力し、同演算器で上記原稿走査信号と
上記補正係数の乗算を行うことによシ、
It has an MO8 type A/D converter with a circuit configuration using a chopper type comparator, a ROM, a RAM, and an arithmetic unit.
The correction coefficient is output from the ROM by digitizing it with a converter and inputting it as an address signal to the ROM, and the correction coefficient Fl'f is stored in the RAM, and then input from the scanner. The original scanning signal is digitized by the A/D converter and inputted to the computing unit, and at the same time, the correction coefficient is read from the RAM and input to the computing unit 1.The computing unit converts it into the original scanning signal. By multiplying the above correction coefficient,
JP58204031A 1983-10-31 1983-10-31 Device for correcting shading distortion Pending JPS6096076A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP58204031A JPS6096076A (en) 1983-10-31 1983-10-31 Device for correcting shading distortion

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP58204031A JPS6096076A (en) 1983-10-31 1983-10-31 Device for correcting shading distortion

Publications (1)

Publication Number Publication Date
JPS6096076A true JPS6096076A (en) 1985-05-29

Family

ID=16483607

Family Applications (1)

Application Number Title Priority Date Filing Date
JP58204031A Pending JPS6096076A (en) 1983-10-31 1983-10-31 Device for correcting shading distortion

Country Status (1)

Country Link
JP (1) JPS6096076A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61277269A (en) * 1985-05-31 1986-12-08 Matsushita Electric Ind Co Ltd Color picture reader
US5430559A (en) * 1988-12-22 1995-07-04 Minolta Camera Kabushiki Kaisha Image reading apparatus with improved output correction of image signal

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS56157575A (en) * 1980-05-09 1981-12-04 Hitachi Ltd Signal procession device
JPS5815369A (en) * 1981-07-22 1983-01-28 Fujitsu Ltd Signal processing system

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS56157575A (en) * 1980-05-09 1981-12-04 Hitachi Ltd Signal procession device
JPS5815369A (en) * 1981-07-22 1983-01-28 Fujitsu Ltd Signal processing system

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61277269A (en) * 1985-05-31 1986-12-08 Matsushita Electric Ind Co Ltd Color picture reader
US5430559A (en) * 1988-12-22 1995-07-04 Minolta Camera Kabushiki Kaisha Image reading apparatus with improved output correction of image signal

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