JPS631249A - Picture reading device - Google Patents
Picture reading deviceInfo
- Publication number
- JPS631249A JPS631249A JP61145208A JP14520886A JPS631249A JP S631249 A JPS631249 A JP S631249A JP 61145208 A JP61145208 A JP 61145208A JP 14520886 A JP14520886 A JP 14520886A JP S631249 A JPS631249 A JP S631249A
- Authority
- JP
- Japan
- Prior art keywords
- maximum value
- image signal
- reference plate
- white reference
- threshold value
- 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
Links
- 238000003705 background correction Methods 0.000 claims abstract description 10
- 238000001514 detection method Methods 0.000 claims description 14
- 238000004140 cleaning Methods 0.000 abstract 1
- 230000007423 decrease Effects 0.000 description 5
- 230000006866 deterioration Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 230000002542 deteriorative effect Effects 0.000 description 1
- 238000002845 discoloration Methods 0.000 description 1
- 238000005562 fading Methods 0.000 description 1
- 238000005286 illumination Methods 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000013139 quantization Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
Landscapes
- Facsimile Scanning Arrangements (AREA)
- Facsimile Image Signal Circuits (AREA)
- Image Input (AREA)
Abstract
Description
【発明の詳細な説明】
産業上の利用分野
本発明は、ファクシミリあるいはスキャナ装置等のよう
に、光源より原稿に光を照射し、その反射光あるいは透
過光を光電変換して画信号を得る画像読取装置に関する
。DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an image processing apparatus, such as a facsimile or scanner device, in which a document is irradiated with light from a light source and the reflected or transmitted light is photoelectrically converted to obtain an image signal. Regarding a reading device.
従来の技術
ＣＯＤ等の固体イメージセンサを用いた画像読取装置を
構成する場合、１画素毎のシェーディング補正（例えば
特開昭５９−２２６５５８号公報）が実現されている。BACKGROUND ART When configuring an image reading device using a solid-state image sensor such as a conventional COD, shading correction for each pixel (for example, Japanese Patent Application Laid-Open No. 59-226558) is realized.
以下第２図を用いて従来の画像読取装置について説明す
る。A conventional image reading device will be described below with reference to FIG.
第２図において、ｌは白基準板、２は原稿、３は白基準
板１あるいは原稿２０表面を照射する光源、４は光源３
から発して白基準板１あるいは原稿２の表面で反射され
た光を集光するレンズ、５は白基準板１あるいは原稿２
を走査して画信号を得る固体イメージセンサ、６は固体
イメージセンサ５かも出力される画信号を適当な振幅に
増幅する増幅器、７はアナログ画信号をディジタル画信
号に変換するＡ／Ｄ変換器、８は白基準板１を走査して
得た画信号のうち１主走査線分の画信号を記憶するＲＡ
Ｍ、９はｒｌ、ＡＭ８に記憶された画信号に基づいてシ
ェーディング補正係数を算出するＲＯＭ、１０はＡ／Ｄ
変換器７から出力されるディジタル画信号とＲＯＭ９か
ら出力されるシェーディング補正係数を乗算する乗算回
路である。In FIG. 2, l is a white reference plate, 2 is an original, 3 is a light source that illuminates the surface of the white reference plate 1 or the original 20, and 4 is a light source 3.
A lens 5 condenses the light emitted from the white reference plate 1 or the surface of the original 2 and reflected by the surface of the white reference plate 1 or the original 2.
6 is an amplifier that amplifies the image signal output from the solid-state image sensor 5 to an appropriate amplitude, and 7 is an A/D converter that converts the analog image signal into a digital image signal. , 8 is an RA that stores an image signal for one main scanning line among the image signals obtained by scanning the white reference plate 1.
M, 9 is rl, ROM that calculates the shading correction coefficient based on the image signal stored in AM8, 10 is A/D
This is a multiplication circuit that multiplies the digital image signal output from the converter 7 and the shading correction coefficient output from the ROM 9.
上記構成において、その動作を以下に説明する。The operation of the above configuration will be explained below.
原稿２の走査に先立って、毎回白基準板１を走査する。Prior to scanning the original 2, the white reference plate 1 is scanned each time.
その時に得られる画信号は、光源３の光量ムラ、レンズ
４の光量分布の不均一性、固体イメージセンサ５の受光
素子間の感度の不均一性等によるシェーデイング歪を含
んでいる。この画信号の１主走査分をＲＡＭ８に記憶す
る。なお、副走査移動は、図示していない副走査送り手
段によって行なわれる。The image signal obtained at this time includes shading distortion due to unevenness in the light amount of the light source 3, non-uniformity in the light amount distribution of the lens 4, non-uniformity in sensitivity between the light receiving elements of the solid-state image sensor 5, and the like. One main scanning portion of this image signal is stored in the RAM 8. Note that the sub-scanning movement is performed by a sub-scanning feeding means (not shown).
次に原稿２を走査し、原稿２に対応したディジタル画信
号をＡ ／ Ｄ変換器７から得る。この時ディジタル画
信号と同期して、几ＡＭ８に記憶された対応するアドレ
スのディジタル画信号が読み出される。このＩｔ Ａ
Ｍ ８から出力されたディジタル画信号をアドレスとし
て、ＲＯＭ９から次式を満足する補正係数Ｆを出力する
。Next, the original 2 is scanned and a digital image signal corresponding to the original 2 is obtained from the A/D converter 7. At this time, in synchronization with the digital image signal, the digital image signal at the corresponding address stored in the AM8 is read out. This It A
Using the digital image signal outputted from M8 as an address, a correction coefficient F satisfying the following equation is outputted from ROM9.
ｆＸＩｒ／２＝定数
（ここで１は原稿２に対応したディジタル画信号の値、
ＮはＡ ／ Ｄコンバータの量子化ビット数である。）
このようにして算出される各画素毎の補正係数とディジ
タル画信号との乗算を、乗算回路１０で実行し、シェー
デイング歪を補正する。fXIr/2=constant (here, 1 is the value of the digital image signal corresponding to document 2,
N is the number of quantization bits of the A/D converter. ) The correction coefficient for each pixel calculated in this manner is multiplied by the digital image signal in the multiplication circuit 10 to correct shading distortion.
乗算回路１０から出力されるディジタル画信号は、２値
化され、あるいは多階調のままで、外部機器あるいはメ
モリ等に出力される。The digital image signal output from the multiplier circuit 10 is output to an external device, memory, etc., either as a binary signal or as a multi-gradation signal.
発明が解決しようとする問題点
シェーデイング歪の要因のうち、光源３の光量ムラに関
しては、経時変化を伴なう。螢光灯を光源３に用いた場
合には、特に経時変化が大きく、その中央部と端部の光
度差は時間がたつにつれて大きくなりながら、全体の光
度も低下してゆく。Problems to be Solved by the Invention Among the causes of shading distortion, unevenness in the amount of light from the light source 3 is accompanied by a change over time. When a fluorescent lamp is used as the light source 3, the change over time is particularly large, and the difference in luminous intensity between the center and end portions increases as time passes, while the overall luminous intensity also decreases.
そこで、上記構成による従来の画像読取装置では、照度
計等で光源３の光出力を定期的に計測することによって
、光源３の寿命を判断している。Therefore, in the conventional image reading device having the above configuration, the lifespan of the light source 3 is determined by periodically measuring the light output of the light source 3 using an illumination meter or the like.
しかしこのような方法では、保守点検に手間がかかると
同時に、正確な判断ができにくく、白基準板１の退色に
対しては何ら検出する手段がない。However, with such a method, maintenance and inspection are time-consuming, it is difficult to make accurate judgments, and there is no means for detecting discoloration of the white reference plate 1.
本発明は従来技術の以上のような問題を解決するもので
、特別なセンサを用いることなし如、光源３あるいは白
基準板１等の劣化の程度を高精度に検出できる画像読取
装置を提供するものである。The present invention solves the above problems of the prior art, and provides an image reading device that can detect the degree of deterioration of the light source 3 or the white reference plate 1 with high precision without using a special sensor. It is something.
問題点を解決するための手段
本発明は上記問題点を解決するため、白基準板を複数ラ
イン走査して得た画信号の最大値を検出し保持する最大
値検出回路と、光源あるいは白基準板の寿命を判断する
しきい値を設定するしきい値設定器と、前記最大値検出
回路に保持されている値と前記しきい値設定器に設定さ
れている値とを比較する比較器とを設けることにより、
上記目的を達成するものである。Means for Solving the Problems In order to solve the above problems, the present invention provides a maximum value detection circuit that detects and holds the maximum value of an image signal obtained by scanning a plurality of lines on a white reference plate, and a light source or a white reference plate. a threshold value setter for setting a threshold value for determining the lifespan of the board; and a comparator for comparing the value held in the maximum value detection circuit with the value set in the threshold value setter. By providing
This aims to achieve the above objectives.
作用
本発明は上記構成により、白基準板キを複数ライン走査
して得た画信号の最大値が、予め設定したしきい値より
も小さければ、光源あるいは白基準板の寿命と判断する
ものである。According to the above configuration, the present invention determines that the light source or the white reference plate has reached the end of its lifespan if the maximum value of the image signal obtained by scanning multiple lines of the white reference plate is smaller than a preset threshold. be.
実施例
第１図は本発明の画像読取装置の一実施例を示すブロッ
ク結線図である。Embodiment FIG. 1 is a block diagram showing an embodiment of the image reading apparatus of the present invention.
第１図において、１は白基準板、２は原稿、３は光源、
４はレンズ、５は固体イメージセンサ、６は増幅器、７
はＡ ／ Ｄ変換器、９はＩＬＯＭ、１０は乗算回路で
あり、これらは動作も含めて第２図の構成と同様である
。８は白基準板１を複数ライン走査して得た画信号のう
ち各画素位置に対して複数ライン分の画信号の最大値を
記憶するＩｔ Ａ Ｍ、１１は白基準板１を複数ライン
走査して得た画信号の最大値を検出し保持する最大値検
出回路、１２は光源３あるいは白基準板ｌの寿命を判断
するしきい値を設定するしきい値設定器、１３は最大値
検出回路１１に保持されている値としきい値設定器１２
に設定されている値とを比較する比較器、１４は比較器
１３の比較結果を表示する表示器である。In Figure 1, 1 is a white reference plate, 2 is an original, 3 is a light source,
4 is a lens, 5 is a solid-state image sensor, 6 is an amplifier, 7
1 is an A/D converter, 9 is an ILOM, and 10 is a multiplication circuit, which are the same in structure as shown in FIG. 2, including their operation. 8 stores the maximum value of the image signal for multiple lines for each pixel position among the image signals obtained by scanning the white reference plate 1 for multiple lines; 11 stores the maximum value of the image signal for multiple lines obtained by scanning the white reference plate 1 for multiple lines; 12 is a threshold value setting device for setting a threshold value for determining the lifespan of the light source 3 or the white reference plate l; 13 is a maximum value detection circuit that detects and holds the maximum value of the image signal obtained by Values held in the circuit 11 and threshold setter 12
14 is a display device that displays the comparison result of the comparator 13.
上記構成において、以下その動作を説明する。The operation of the above configuration will be explained below.
まず、白基準板１を走査して得たアナログ画信号をＡ／
Ｄ変換器７でディジタル画信号に変換する。白基準板１
にキズ、はこり等が付いている箇所があれば、その箇所
を走査して得た画信号は、局所的に低い値となるため、
このような画信号を基準にしてシェーディング補正を行
なうと画質が低下する。そこで、白基準板１を複数ライ
ン走査して得た画信号のうち各画素位置に対して複数ラ
イン分の画信号の最大値をＲＡＭ８に記憶し、これを基
準にシェーディング補正をする。First, the analog image signal obtained by scanning the white reference plate 1 is
A D converter 7 converts it into a digital image signal. White reference plate 1
If there are scratches, dents, etc. on the image, the image signal obtained by scanning that area will have a locally low value.
If shading correction is performed based on such an image signal, the image quality will deteriorate. Therefore, among the image signals obtained by scanning the white reference plate 1 for a plurality of lines, the maximum value of the image signals for a plurality of lines for each pixel position is stored in the RAM 8, and shading correction is performed using this as a reference.
最大値検出回路１１も、白基準板１に付いたキズ、はこ
り、あるいは白基準板１の退色の影響を避けるため、白
基準板１を複数ライン走査して得た画信号の最大値を検
出、保持する。The maximum value detection circuit 11 also detects the maximum value of the image signal obtained by scanning multiple lines of the white reference plate 1 in order to avoid the effects of scratches, chips, or fading on the white reference plate 1. Detect and retain.
ところで、光源３の光量が低下したり、白基準板１が退
色すると、全体の画信号レベルが低下してくるため、画
質が低下すると同時に、最大値検出回路１１が保持する
最大値も低下してくる。そこで画質を著しく低下させな
いために、最大値検出回路１１が保持すべき値の最小値
を、しきい値設定器１２に設定しておく。そして比較器
１３で、最大値検出回路１１が保持している値と、しき
い値設定器１２に設定した値とを比較し、最大値検出回
路１１が保持している値のほうが小さければ、ランプ等
で構成される表示器１４により表示する。従がって、表
示器１４により、光源３の交換時期あるいは白基準板１
の清掃時期を知ることができる。なお、最大値検出回路
１１は、比較器とラッチ回路により容易に実現できるの
で、その構成については省略する。By the way, when the light intensity of the light source 3 decreases or the white reference plate 1 discolors, the overall image signal level decreases, and at the same time, the image quality decreases and the maximum value held by the maximum value detection circuit 11 also decreases. It's coming. Therefore, in order to prevent the image quality from significantly deteriorating, the minimum value to be held by the maximum value detection circuit 11 is set in the threshold value setting device 12. Then, the comparator 13 compares the value held by the maximum value detection circuit 11 and the value set in the threshold value setter 12, and if the value held by the maximum value detection circuit 11 is smaller, then The information is displayed by a display device 14 composed of a lamp or the like. Therefore, the display 14 indicates whether it is time to replace the light source 3 or the white reference plate 1.
You can know when to clean. Note that the maximum value detection circuit 11 can be easily realized using a comparator and a latch circuit, so its configuration will be omitted.
以上本実施例によれば、白基準板１を走査して得た画信
号の複数ライン分の最大値としきい値とを比較したこと
により、白基準板１の部分的なキズ、汚れに影響されな
い比較が行なえるので、光源３あるいは白基準板１の劣
化の程度を高精度に検出できる。As described above, according to this embodiment, by comparing the maximum value of multiple lines of image signals obtained by scanning the white reference plate 1 with the threshold value, local scratches and dirt on the white reference plate 1 are affected. Since it is possible to perform a comparison without being compared, the degree of deterioration of the light source 3 or the white reference plate 1 can be detected with high accuracy.
発明の効果
以上述べてきたように、本発明によれば、白基準板を走
査して得た画信号の最大値を検出し保持する最大値検出
回路と、任意のしきい値を設定するしきい値設定器と、
前記最大値検出回路に保持された値と前記しきい値設定
器に設定された値とを比較する比較器と、前記比較器の
比較結果を表示する表示手段を設けることにより、前記
白基準板に付いたキズ、汚れに影響されず、光源あるい
は白基準板の劣化の程度を高精度に検出できる。Effects of the Invention As described above, according to the present invention, a maximum value detection circuit that detects and holds the maximum value of an image signal obtained by scanning a white reference plate, and an arbitrary threshold value can be set. a threshold setter;
By providing a comparator for comparing the value held in the maximum value detection circuit with a value set in the threshold value setting device, and a display means for displaying the comparison result of the comparator, the white reference plate The degree of deterioration of the light source or white reference plate can be detected with high accuracy without being affected by scratches or dirt on the white reference plate.
第１図は本発明の一実施例における画像読取装置のブロ
ック結線図、第２図は従来の画像読取装置のブロック結
線図である。
１・・・白基準板、３・・・光源、１１・・・最大値検
出回路、１２・・・しきい値設定器、１３・・・比較器
、１４・・・表示器。
代理人の氏名 弁理士 中 尾 敏 男ほか１名Ｉｒ図FIG. 1 is a block wiring diagram of an image reading apparatus according to an embodiment of the present invention, and FIG. 2 is a block wiring diagram of a conventional image reading apparatus. DESCRIPTION OF SYMBOLS 1...White reference plate, 3...Light source, 11...Maximum value detection circuit, 12...Threshold value setter, 13...Comparator, 14...Display device. Name of agent: Patent attorney Satoshi Nakao and one other person
Claims (1)
より画信号を得る固体イメージセンサと、前記固体イメ
ージセンサにより得た画信号をディジタル信号に変換す
るＡ／Ｄ変換器と、前記Ａ／Ｄ変換器から出力される画
信号の一主走査分を記憶する記憶手段と、前記記憶手段
に記憶された内容によりシェーディング補正係数を決定
する係数決定手段と、前記係数決定手段のシェーディン
グ補正係数に基づきシェーディング補正演算を行なう乗
算回路と、前記白基準板を走査して得た画信号の最大値
を検出し保持する最大値検出回路と、任意のしきい値を
設定するしきい値設定器と、前記最大値検出回路に保持
された値と前記しきい値設定器に設定された値とを比較
する比較器と、前記比較器の比較結果を表示する表示手
段を具備することを特徴とする画像読取装置。a white reference plate, a solid-state image sensor that obtains an image signal from light reflected or transmitted from the original by a light source, an A/D converter that converts the image signal obtained by the solid-state image sensor into a digital signal, and the A/D converter. a storage means for storing one main scanning portion of the image signal output from the converter; a coefficient determination means for determining a shading correction coefficient based on the contents stored in the storage means; and a coefficient determination means for determining a shading correction coefficient based on the shading correction coefficient of the coefficient determination means. a multiplication circuit that performs a shading correction operation; a maximum value detection circuit that detects and holds the maximum value of the image signal obtained by scanning the white reference plate; and a threshold value setter that sets an arbitrary threshold value; An image characterized by comprising: a comparator for comparing the value held in the maximum value detection circuit with a value set in the threshold value setting device; and a display means for displaying the comparison result of the comparator. reading device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61145208A JPS631249A (en) | 1986-06-20 | 1986-06-20 | Picture reading device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61145208A JPS631249A (en) | 1986-06-20 | 1986-06-20 | Picture reading device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS631249A true JPS631249A (en) | 1988-01-06 |
Family
ID=15379889
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP61145208A Pending JPS631249A (en) | 1986-06-20 | 1986-06-20 | Picture reading device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS631249A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02109459A (en) * | 1988-10-19 | 1990-04-23 | Canon Inc | Picture reader |
| US6816623B1 (en) | 1998-06-11 | 2004-11-09 | Canon Kabushiki Kaisha | Image reading apparatus providing shading compensation related to the on-time of the light source |
| JP2013254177A (en) * | 2012-06-08 | 2013-12-19 | Canon Inc | Image forming apparatus |
-
1986
- 1986-06-20 JP JP61145208A patent/JPS631249A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02109459A (en) * | 1988-10-19 | 1990-04-23 | Canon Inc | Picture reader |
| US6816623B1 (en) | 1998-06-11 | 2004-11-09 | Canon Kabushiki Kaisha | Image reading apparatus providing shading compensation related to the on-time of the light source |
| JP2013254177A (en) * | 2012-06-08 | 2013-12-19 | Canon Inc | Image forming apparatus |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US7183532B2 (en) | Detecting a defect in an image scanner | |
| US7558437B2 (en) | Method and apparatus for image processing | |
| EP0744862B1 (en) | A method of and apparatus for correcting the output signals of a plurality of photodetecting elements | |
| JP2005065276A (en) | System and method for automatic correction of illumination noise caused by ambient light | |
| US6295383B1 (en) | Intensity correction in an optical scanner | |
| US7251064B2 (en) | Calibration of an image scanning system | |
| JPS631249A (en) | Picture reading device | |
| US6518587B2 (en) | Detection and correction of defects from scanner calibration references | |
| JP2001086333A (en) | Image reader and image processor provided with the image reader | |
| JPH05180781A (en) | Method and apparatus for surface defect inspection | |
| JPS63155869A (en) | Image reader | |
| JP2001285594A (en) | Image reader, shading fault detection method, and storage medium | |
| JPH04362789A (en) | Picture input device | |
| JP3086477B2 (en) | Image capture device | |
| JPS61242170A (en) | Signal processor | |
| JPS61257069A (en) | Correcting method for quantity of light variation | |
| JPS58182958A (en) | Information reader | |
| JPH0158909B2 (en) | ||
| JP2002305655A (en) | Method for specifying defective position of shading correction plate in image reader | |
| JPS63155868A (en) | Image reader | |
| JPS6156573A (en) | Detector for deterioration of light source of picture reader | |
| JPS6337775A (en) | Image detecting system for facsimile | |
| JPH0253375A (en) | Reading part dirt detecting circuit | |
| JPH1127525A (en) | Image reader | |
| JPH0199370A (en) | Circuit for detecting stain of read section |