JPS5853269A - Texture eliminating circuit - Google Patents

Texture eliminating circuit

Info

Publication number
JPS5853269A
JPS5853269A JP56151185A JP15118581A JPS5853269A JP S5853269 A JPS5853269 A JP S5853269A JP 56151185 A JP56151185 A JP 56151185A JP 15118581 A JP15118581 A JP 15118581A JP S5853269 A JPS5853269 A JP S5853269A
Authority
JP
Japan
Prior art keywords
image signal
level
signal
image
peak
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.)
Granted
Application number
JP56151185A
Other languages
Japanese (ja)
Other versions
JPH0328110B2 (en
Inventor
Yoshiaki Kamimoto
神本 芳明
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.)
Ricoh Co Ltd
Original Assignee
Ricoh 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 Ricoh Co Ltd filed Critical Ricoh Co Ltd
Priority to JP56151185A priority Critical patent/JPS5853269A/en
Publication of JPS5853269A publication Critical patent/JPS5853269A/en
Publication of JPH0328110B2 publication Critical patent/JPH0328110B2/ja
Granted legal-status Critical Current

Links

Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/40Picture signal circuits

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Image Input (AREA)
  • Facsimile Image Signal Circuits (AREA)

Abstract

PURPOSE:To make the reference point of an image signal follow the change of level of the original texture and to secure the offset of the image signal, by detecting the peak value of the image signal on the basis of the black level and subtracting the output of detection from the image signal to convert it into an image signal on the basis of the white level. CONSTITUTION:An image signal A read out through a CCD solid state image pickup element 1 is amplified 2, and the peak voltage of the signal A is detected by a peak holding circuit 3. The difference between the signal A and the peak value B is obtained through an operational amplifier 4. In this case, the signal A is based on the black level in the original image in terms of the zero reference, and the arithmetic output F is based on the peak level of the signal A in terms of the zero reference. Thus the black level information is converted into an image signal emerging at the minus side. Then the output F is inverted by a polarity inverting amplifier 5. As a result, the texture level component is compensated compared with the signal A for an image signal which is based on the white level.

Description

【発明の詳細な説明】 本発明は、画1象而を露′WS走査して胱取られた画像
情報の中から地肌レベル分を除去する地肌除去回路に関
する。
DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a background removal circuit that removes information at the background level from image information obtained by scanning a single image with a WS.

−ffに、コンタクトガラス上にのせられた原稿画像を
瞑光ランフ−により走査してその反射光を撮像素子によ
って受光させてその画像情報を砂、取り、その読取られ
た画像情報にもとづいて画像の記録を行なわせろ画像入
出力装置にあってをは、絖取られた画像情報の中から原
稿地肌の濃度レベル分を除去して、地肌汚れのない品質
の良い記録画像を得ることができるように画像処理を施
している。
-ff, the original image placed on the contact glass is scanned by a light-reflecting lamp, the reflected light is received by an image sensor, the image information is captured, and an image is created based on the read image information. The image input/output device is designed to remove the density level of the original background from the image information that has been removed, so that a high-quality recorded image without background stains can be obtained. Image processing is applied to the image.

従来、地肌除去の手段として、読取らn、たl[11i
1象情報の基準点を予め見込んだ地肌レベル分だけオフ
セットさせるよつにしているが、このような手段では地
肌濃度が糧々異なる原mに応じた適切な地肌除去を容易
に行なわせることができず、また特に1つの原稿中に2
ける地肌レベルが部分的に異なるような場合にはその変
化に何ら追従することができずに地肌除去にバラツキを
生じてしまい、記録画像中に部分的な地肌汚n、が残り
て画質が低下してしまうという問題がある。
Conventionally, as a means of background removal, reading n, ta l[11i
The reference point of one-image information is offset by a predetermined background level, but with this method, it is not possible to easily perform appropriate background removal according to the background density, which varies considerably. It is not possible, and especially if there are two
If the background level removed differs locally, it will not be possible to follow the changes and variations will occur in the background removal, leaving partial background stains in the recorded image and deteriorating the image quality. The problem is that you end up doing it.

本発明は、このような点を考慮してなされたもので、画
像情報の基準点を原稿地肌のレベル変化に追従させてオ
フセットさせるよつにした地肌除去回路を提供するもの
である。
The present invention has been made in consideration of these points, and provides a background removal circuit that offsets a reference point of image information by following changes in the level of the background of a document.

第1図に本発明に係る地肌除去回路の基本構成を示すも
ので、CCD 固体ml象素子lによって絖取られ、か
つビデオ増幅器2によって増幅された画像信号A中のピ
ーク電圧値を検出して保持するピークホールド回路3と
、そのホールド出力Bと前記画1象信号Aとにもとづい
て次式にもとづく演算処理を行なわせる演算増幅器4と
、その演算出力Fの極性を反転させる極性反転用増幅器
5とによって構成されている。
FIG. 1 shows the basic configuration of the background removal circuit according to the present invention, which detects the peak voltage value in the image signal A removed by the CCD solid-state image element l and amplified by the video amplifier 2. A peak hold circuit 3 for holding, an operational amplifier 4 for performing arithmetic processing based on the following equation based on its hold output B and the image signal A, and a polarity inversion amplifier for inverting the polarity of its operational output F. 5.

F=A−B     ・・・(1) このように構成されたものにあって、いまCCD固体撮
像素子1によって第21%l (a)に示されるよつな
画像情報が絖取られた場合を想定してみる。その画像信
号へは原稿画像中の黒レベルBLを零基準とし、そのピ
ーク電圧値Bと白レベル電圧値WHとの差W)f−Bが
地肌レベル分として現nてG)る。
F=A-B (1) If the image information shown in the 21st %l (a) is removed by the CCD solid-state image sensor 1 in this configuration, Let's imagine. For the image signal, the black level BL in the original image is used as a zero reference, and the difference W)f-B between the peak voltage value B and the white level voltage value WH is calculated as the background level.

したがって、その蜘像信gAのピーク電圧値Bがピーク
ホールド回路3によって検出保持され、(3) そのホールド出力Bと画1象信号Aとにもとづいて演算
増幅器41Cよって前記(1)式の演算処理がなされる
と、その演算出力Fぼ第2図(b)に示されるように、
もとの画像信号へのピークレベルを零基準にして黒レベ
ル情報BLがマイナス側に現れる画像信号に変換される
ことになる。次いで、その演算出力Fを極性反転用増幅
器5によって反転させると、第2図(C)に示され、る
よつに、もとの画1象倶shに比べてその地肌レベル分
WH−Bが除去された白レベルWH’を零基準とする画
像信号がその出力端OUT  K侍らn、ることに1よ
る。
Therefore, the peak voltage value B of the spider image signal gA is detected and held by the peak hold circuit 3, and (3) the operational amplifier 41C calculates the above equation (1) based on the hold output B and the image signal A. When the processing is performed, the calculation output F is as shown in FIG. 2(b),
The black level information BL is converted into an image signal that appears on the negative side with the peak level of the original image signal as a zero reference. Next, when the calculation output F is inverted by the polarity inversion amplifier 5, as shown in FIG. An image signal whose zero reference is the white level WH' from which WH' has been removed is sent to its output terminal OUT.

このように、本発明による地肌除去回路では、原稿の糧
類によって地肌レベルが変動し、また原稿地肌のレベル
が部分的に変化する場合であっても、そn、に追従した
地肌レベルの除去を有効に行なわせろことができるもの
と1jる。な3、地肌レベルの除去がなされた画像・1
g号にもとづき、量子化などを行なわせるその後の画像
処理回路1cE(,1て、それがマイナス4M号を取扱
える回路構成であわ、ば、前記実施例の場合のように演
′xJ百幅器4の(4) 出力Fを極性反転用増幅器5によって反転させる必要が
ないことばいうまでもない。
As described above, in the background removal circuit according to the present invention, even if the background level changes depending on the type of food on the document, and even if the background level of the document changes partially, the background level removal circuit according to the present invention can remove the background level that follows the background level. 1j. 3. Image with background level removed 1
The subsequent image processing circuit 1cE performs quantization, etc. based on the number g (if it has a circuit configuration that can handle the minus 4M number, then, as in the case of the previous embodiment, (4) It goes without saying that it is not necessary to invert the output F of the device 4 using the polarity inverting amplifier 5.

このような地肌除去回路にあって、CCD固体撮像素子
1によりて仇取られ、た画像信号のピークレベル(地肌
レベル)が第3図に示すように高周波成分を含んでバラ
ツキを生じてしまうと最適な地肌除去を行なわせること
ができないため、特に本発明では補償電圧Cを与えてそ
の地肌レベルのバラツキによる影1#をなくすようにす
るものである。
In such a background removal circuit, if the peak level (ground level) of the image signal removed by the CCD solid-state image sensor 1 contains high frequency components and causes variations as shown in FIG. Since optimum background removal cannot be performed, the present invention applies a compensation voltage C to eliminate shadow 1# due to variations in the background level.

その際、ピークホールド回43のホールド出力Bに一定
の大きさの補償電圧C′を加え、その結果B+C’ を
画イ象信ghから差し引くことによって地肌レベルのバ
ラツキを画一的に修正する方法が考えられるが、このよ
つな方法では一定の補償電圧が画像信号Aの入力レベル
に対応せず、そのため第4図(a) 、 (b)に示す
よつに高反射率原稿の場合(a)と低反射率原稿(b)
の場合とでは地肌濃度近辺の再現性が悪くなってしまう
といつ問題がある。
At that time, a method of uniformly correcting variations in the background level by adding a compensation voltage C' of a certain magnitude to the hold output B of the peak hold circuit 43 and subtracting the result B + C' from the image signal gh. However, in this type of method, the constant compensation voltage does not correspond to the input level of the image signal A, and therefore, in the case of high reflectance originals as shown in Figures 4(a) and (b), a) and low reflectance original (b)
In this case, there is a problem when the reproducibility near the background density deteriorates.

そこで、本発明による地肌除去回路にあっては、原稿地
肌の高周波成分を原稿の反射率によって変化させて地肌
濃度近辺の再現性を良くするようにしている。
Therefore, in the background removal circuit according to the present invention, the high frequency component of the background of the original is changed depending on the reflectance of the original to improve the reproducibility near the background density.

第5図は本発明による地肌除去回1略の一実施例を示す
もので、@1図に示した基本回路にあって、一定電圧V
8をピークホールド回Nr30ホールド出力Bで乗算す
る乗算器6を設け、その乗算出力を補償電圧Cとして演
算増幅器4に与え、そこでCCDCD固体酸1象素子1
って読取らnlかっビデオ増幅器2によって増幅された
原稿の画1象信号Aとピークホールド回路3によって検
出さnた画像信号Aのピーク値Bとにもとづいて次式の
演算処理を実行させ、その演算出力Fを極性反転用増幅
器5に与えるようにしている。
FIG. 5 shows an embodiment of the background removal circuit 1 according to the present invention.
A multiplier 6 is provided for multiplying 8 by the peak hold times Nr30 and the hold output B, and the multiplier output is applied as a compensation voltage C to the operational amplifier 4, where the CCDCD solid acid 1-quadrant element 1
Based on the original image signal A amplified by the video amplifier 2 and the peak value B of the image signal A detected by the peak hold circuit 3, the calculation process of the following equation is executed. The calculated output F is supplied to the polarity inversion amplifier 5.

F=A−B+C・・・(2) ここで、補償電圧C(1次式によって与えられろことに
なり、それが原稿地肌部の高周波変動分に相当するもの
となる。
F=A-B+C (2) Here, the compensation voltage C (given by a linear equation) corresponds to the high-frequency fluctuation of the background portion of the original.

C=に−VR−B    −(3) ただし、kば定数、VRは補償電圧によって決まる一定
電圧である。
C=-VR-B-(3) where k is a constant and VR is a constant voltage determined by the compensation voltage.

また、補償電圧C=0はないために、次式に示すよつに
、(3)式にオフセット区圧Vof  を加えたものを
補償電I:F、Cとして用いるようにすることも可能で
ある。
In addition, since the compensation voltage C=0 does not exist, it is also possible to add the offset voltage Vof to equation (3) and use it as the compensation voltage I:F, C, as shown in the following equation. be.

C= k−V、+! ・B + Vof    ”・(
4)fj′Oj6、本発明による地肌除去回路にあって
は第5図の実施例のものに何ら限定されるものではなく
、前記(2)式に8ける補償電圧Cを作る際、除算器6
を用いる代わりに、その他ピークホールド回路3の出力
によって制御することのできろ例えばホトカブラによる
アッテネータやアナロクマルナツライヤによる乗算器な
どの手段を用いることによっても容易に達成できること
ばいつまでも1.fい。
C=k-V,+!・B + Vof”・(
4) fj'Oj6, the background removal circuit according to the present invention is not limited to the embodiment shown in FIG. 6
Instead of using , it can be easily achieved by using other means that can be controlled by the output of the peak hold circuit 3, such as an attenuator using a photocoupler or a multiplier using an analog multiplier. F.

以上、本発明による地肌除去回路にあっては、撮像素子
によって読取らnた黒レベル基準とする画像信号のピー
ク値を検出するピークホールド回路と、一定電圧をピー
クホールド回1烙の出力レベルで可変させることによっ
て地肌部の高周波変動分に応じた補償電圧を作成する手
段と、胱取られ(7) た画像信号からそのピーク値を差引くとともに補償電圧
値を加える演算回路と、その演算出力の極性を反転させ
て白レベル基準の画it信号にf換させる手段とによっ
て構成されたもので、原稿の地肌レベルの高周波変動分
に追従してその地肌レベル分の除去を有効に行なわせる
ことができるという優れた利点を有している。
As described above, the background removal circuit according to the present invention includes a peak hold circuit that detects the peak value of an image signal read by an image sensor and used as a black level reference, and a constant voltage at an output level of one peak hold cycle. Means for creating a compensation voltage according to the high frequency fluctuation of the skin by making it variable; an arithmetic circuit that subtracts the peak value from the captured image signal and adds the compensation voltage value; and the arithmetic output thereof. and a means for inverting the polarity of the signal and converting it into an image IT signal based on a white level, thereby effectively removing the background level by following high frequency fluctuations in the background level of the original. It has the excellent advantage of being able to

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

第1図は本発明に係る地肌除去回路の基本構成を示すブ
ロック図、第2図(a) 、 (b) 、 (C)はそ
の基本回路に2ける各部信号の一例を示す特性図、第3
図は入力画像信号の一例を示T%性図、第4図(a)。 (b)は補償電圧を一定としたときの高反射率原稿の場
合と低反射率原種の場合とに2ける画像再生信号の一例
をそn、それ示す特性図、第5図は本発明による地肌除
去回路の一実施例を示すブロック構成図である。 l・・・CCD固体撮像素子  2・・・ビデオ増幅器
3・・・ピークホールド回路  4・・・演算増幅器(
8) 5・・・極性反転用増幅器  6・・・乗算器出願人代
理人 鳥 井   消 第1図 第2図
FIG. 1 is a block diagram showing the basic configuration of the background removal circuit according to the present invention, FIGS. 3
The figure shows an example of an input image signal and is a T% characteristic diagram, FIG. 4(a). (b) shows an example of the image reproduction signal in the case of a high-reflectance original and the case of a low-reflectance original when the compensation voltage is constant; FIG. FIG. 2 is a block configuration diagram showing an example of a background removal circuit. 1... CCD solid-state image sensor 2... Video amplifier 3... Peak hold circuit 4... Operational amplifier (
8) 5...Amplifier for polarity reversal 6...Multiplier Applicant's agent Suzuki Torii Figure 1 Figure 2

Claims (1)

【特許請求の範囲】[Claims] 撮像素子によって読取られた黒レベル基準とする画像信
号のピーク値を検出するピークホールド回路と、一定電
圧をピークホールド回路の出力レベルで可変させること
によって地肌部の高周波変動分に応じた補償電圧を作成
する手段と、読取られた画像信号からそのビーク1直を
差引くとともに補償′駐圧値を加える演算回路と、その
演算出力の極性を反転させて白レベル基準の画像信号に
変換させる手段とによって構成された地肌除去回路。
A peak hold circuit detects the peak value of the image signal read by the image sensor and is used as a black level reference, and a constant voltage is varied by the output level of the peak hold circuit to adjust the compensation voltage according to high frequency fluctuations in the background. an arithmetic circuit that subtracts the first peak value from the read image signal and adds a compensating pressure value; and a means that inverts the polarity of the arithmetic output to convert it into an image signal based on a white level. A background removal circuit configured by.
JP56151185A 1981-09-24 1981-09-24 Texture eliminating circuit Granted JPS5853269A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP56151185A JPS5853269A (en) 1981-09-24 1981-09-24 Texture eliminating circuit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP56151185A JPS5853269A (en) 1981-09-24 1981-09-24 Texture eliminating circuit

Publications (2)

Publication Number Publication Date
JPS5853269A true JPS5853269A (en) 1983-03-29
JPH0328110B2 JPH0328110B2 (en) 1991-04-18

Family

ID=15513134

Family Applications (1)

Application Number Title Priority Date Filing Date
JP56151185A Granted JPS5853269A (en) 1981-09-24 1981-09-24 Texture eliminating circuit

Country Status (1)

Country Link
JP (1) JPS5853269A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62235873A (en) * 1986-04-04 1987-10-16 Canon Inc Picture reader

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5416918A (en) * 1977-07-07 1979-02-07 Mitsubishi Electric Corp Background density compensating circuit

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5416918A (en) * 1977-07-07 1979-02-07 Mitsubishi Electric Corp Background density compensating circuit

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62235873A (en) * 1986-04-04 1987-10-16 Canon Inc Picture reader

Also Published As

Publication number Publication date
JPH0328110B2 (en) 1991-04-18

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