JPS6096955A - Shading correcting device - Google Patents

Abstract

PURPOSE:To execute high-performance shading correction by photoelectric-transferring light passing through the corresponding color filter and by correcting its output signal by the correction coefficient signal in a memory circuit, which stores the shading correction coefficient. CONSTITUTION:A comparator 16 compares a voltage Vo sent from a operation processing circuit 15 with a reference voltage Vr for an uniform reflecting surface by a photoelectric transfer element 1, obtains a correction coefficient making Vo=Vr, and stores it in a memory circuit 9. A correction coefficient Vy and the special correction quantity by color stored in a memory circuit 10 are taken out, and multiplied by multiplier 11. As a result, the shading correction coefficient, where balance between colors is brought into harmony, is stored in a memory circuit 12. When an original is read out, the signal photo-electric-transferred the light passing through the corresponding color filter can be corrected by the correction coefficient stored in the circuit 12.

Description

[Detailed description of the invention]

(+, technical field) The present invention is a method for determining the amount of light photoelectric conversion in a color image 1τ+IIi (: station 1r1, etc.) '477 ('I
of? +1i ij: relates to a shedding correction device. (Prior art) The light source of the lamp housing 9 (-light QJ L,
The anti-Q j light is guided through an optical system to a solid-state image element such as T C ('; 1.) or a photoelectric conversion element such as a photoelectric conversion element, Recording devices that can quickly reproduce images are already widely known. The recording device of this scale has a uniformity of 1lifl i!
Even if you cross over the surface of the original document, the output waveform of the photoelectric converter
For example, if we consider a single photoelectric conversion element for example, the so-called shading phenomenon in which the edges of the pixels at the edges are lower than the pixels at the center is the cause of points 1 and 2. The following factors are considered: the light attenuation effect by the lens of the optical system, the irrespective of electric shock due to the amount of photoelectric conversion r, and the unevenness of the illuminant IU'1 of the illumination lamp and changes in illuminance.

[ru. Like this] -1? rili ink phenomenon 1lI7
Conventionally, various correction measures have been taken to prevent this.
Book 1: Shaping can be corrected by processing the output from the image sensing element, or the shading waveform can be stored in a memory element such as RAM, and the contents of the memory element can be read out and corrected during photoelectric conversion of the original surface. There are things etc. However, there are only a few studies on shading correction in this type of plane scanning type LIT imaging device. (Object of the Invention) In view of the above points, the purpose of the present invention is to provide a multi-cuff image +1i1 image device 6'@J
The object of the present invention is to realize a shading correction device with 7:+I higher performance than IJ. (Li and l composition of the invention) The present invention that achieves this object includes a photoelectric conversion element that converts each reflected light on a uniformly irregular surface and a document surface into an electric signal, and a uniformly irregular Receiving the reflected light from the surface h)
a first correction means for equalizing the output of r'Ic electric substation test r; a first storage means for pre-recording a specific correction amount for each name color; J to the correction means, Rimeda compensation i1 coefficient and each e stored in the first storage means.
+f+j's 1(ljilLit) and the second correction coefficient for each color fO, and the second ?i11i',lE means: Each (!21i
Second record 1Q to memorize the tll'+ iE l series of j
Means to '! If! i L/, in actual delivery, the corresponding color is the signal obtained by photoelectrically converting the passing light. :1 means is characterized in that it is configured to perform correction using correction coefficients stored in the means. (Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Figure 1 shows an example of a small tIlj from Kiba! It is the cause of frost. J3 in the figure, 1 is the original 1i'i tlJ
-)"C' f1^ Photoelectric conversion element such as CD, which changes to the signal, 2 3 receives the output h(!1 of the photoelectric conversion element 1 and the output e2 of the reference voltage generator 20)'(18 according to the difference between e and e? It is a differential amplifier that outputs Co. As a pano JC?, selector switch Stk2 outputs Ea,
Fll, 1iiJ of []c) are selected and 'j' is obtained. IJ: Generate clock pulse Riruri1
5 is a frequency dividing circuit 1ii+ which receives the output of the clock generator 1 circuit 4, and 6 is a control circuit which receives the output of the frequency dividing circuit 5 and performs various controls 11. The output φ of the output circuit 4 and the output φ2G of the frequency dividing circuit 5,
Changeover switch S? Either one is selected by 1ii
The first transfer control pulse φ (receives the output of the 7131 clock generation circuit 4) is applied to the photoelectric transformer AI 'f'I to transfer the second transfer control pulse to the charging transformer J''-1. E3 receives the output of the control circuit 6 (a timing circuit that generates each timing pulse and address signal, 1).
Reno data sent from RAL1 circuit 6]
I/! F toshi (receive) the Suitsuji S3, and il the contents
10 is a special memory circuit for each color ffj], and a second memory circuit that stores Y-(supplement iE m for color balance), '+ i tit
The output of the first memory circuit 5) and the second memory circuit 10 are received by the Higashiguchi device, which performs the heavy-duty operation, and the third Higashiguchi device 12 stores the results of the east-exiting device for each color. The following are the 10 circuits. i
3 +, Convert either fiJ of the output of the 1 control circuit 6 or the third memory circuit 12 into the input 1-11 ab [1 gui, 3), /△change 1 momme device, input / Switching of J is performed by switching switch FS4). Timing rotation
The output J of 88 is the first to S3 memory circuits 9 after A4. 'IO, 12 is given as an address signal. '14 is the output 0 of the differential amplifier 3 (a lean-pull hold circuit that pulls + to a small root, i3i LJ, the outputs of the Lindslure 1 to pull circuit 14, and the output 1) of the /Δ converter '13. 11 after receiving the JVV
The processing circuit for the performance Q, 1G, is the processing circuit for the performance Q processing circuit VfI i ! 5
Compare the output J VO with 阜iXL 1) fj V r and illuize 1-i, 11 1111 times iri+
6 Nill;,? - i, Li, i! ,
' i direct V r IJ, basis ill electric 1-t I-s III: I+'CI+, min EI-,,l, with I'<p
It can be changed as follows. '8 in Rimple Elementary School
'I 'I's 1 non-shilling pulse (J, from the frequency divider circuit 5 C comparison 23'1G has Jj.
Is there a sequence for each color? 111 correct! III
It is sent as an Ilt signal to a subsequent image processing circuit (not shown). The operation of the shading correction device configured as described above is as follows. First, the case of calculating the shading correction coefficient for a uniform reflective surface will be explained. At this time, it is assumed that the switches S1 to S5 are in the positions shown in FIG. Reflected light from a uniform reflection surface (not shown) is applied to the photoelectric conversion element 1, and the reflected light is photoelectrically converted. This photoelectric conversion signal c1
enters the differential amplifier 3 and is compared with the reference voltage e2 from the reference voltage generator 2. The differential amplifier 3 generates a signal e0 corresponding to the difference between e1 and e2, and e0 is held in the subsequent sample and hold circuit 14. The sample hold circuit 1
The hold output VX of No. 4 enters one input terminal of the arithmetic processing circuit 15. On the other hand, the control circuit 6 outputs predetermined data for shading correction, and the D/A converter 1
3, it is converted to an analog signal. This D/A converter 13
The output Vy enters the other input terminal of the arithmetic processing circuit 15. The arithmetic processing circuit 15 receives Vx input and Vy input, performs the calculation Vx·Vy, and converts the result to V0 (=Vx·Vy).
Vy). V0 enters comparator 16 via switch S5. The comparator 16 is provided with a reference voltage Vr for the uniform reflective surface, and compares the voltage V0 sent from the arithmetic processing circuit 15 with the reference voltage Vr. The result is transmitted from the comparator 16 to the control circuit 0. The control circuit 6 determines Vy such that Vo=Vr from the output of the comparator 16, and uses this as a correction coefficient in the first storage circuit 9.
Store in. That is, when V0>Vr, it means that the sensitivity of the photoelectric conversion element 1 is over, so the value of Vy is made small to compensate for the oversensitivity, and conversely, when V0<Vr, it means that the sensitivity of the photoelectric conversion element 1 is insufficient. Therefore, the value of Vv is increased to compensate for the lack of sensitivity, and a correction coefficient for making the output of the photoelectric conversion element 1 uniform is stored in the storage circuit 9. In this way, the first storage circuit 9 stores shading correction coefficients for correcting the spatial distribution of the amount of light caused by the light source, lens, photoelectric conversion element, and the like. Next, the case of calculating the shading correction coefficient for each color will be explained. At this time, the connections of the switches S3 to S5 are reversed as shown in FIG. The correction coefficient stored in the first storage circuit 9 and the second storage circuit 1
A unique correction amount for each color stored in 0 is taken out and multiplied by a multiplier 11. The result is the third storage circuit 12
is stored for each color as a shading correction coefficient for the light transmitted through the color filter. That is, the third storage circuit 12 stores shading correction coefficients in which color balance is achieved between each color. Regarding the correction for each color, as shown in FIG. 3, the output level of the signal after passing through the color filter is completely different depending on the color. In the figure, the horizontal axis shows the type of color, and the vertical axis shows the output voltage of the photoelectric conversion element 1, respectively. Incidentally, the △ mark indicates the characteristic without a filter, the X mark indicates the characteristic after passing through the red filter, the .-mark indicates the characteristic after passing through the blue filter, and the ◯ mark indicates the characteristic after passing through the green filter. Further, WW indicates a reference level line after the output voltage is corrected. Therefore, correction is performed for each color to achieve this description level, and the necessary correction amount for each color is stored in advance in the second storage circuit 10 as described above. When reading actual document information, the image signal read by the photoelectric conversion element 1 is multiplied by the shading correction coefficient for each color stored in the third storage circuit 12 in the arithmetic processing circuit 15, and a shading-corrected color signal is obtained. is output and sent to a subsequent image processing device (not shown). That is, the image signal e1 read by the photoelectric conversion element 1 is sent to the differential amplifier 3.
is converted into a signal e0 according to the difference from a predetermined reference voltage 2, and then sent to the arithmetic processing circuit 1 via the sample and hold circuit 14.
5 as the measurement signal Vx. On the other hand, the correction coefficient for each color stored in the third storage circuit 12 is stored in the switch S4.
The signal enters the D/A converter 13 via the D/A converter 13, is converted into an analog signal, and is then provided to the arithmetic processing circuit 15 as a new correction signal Vy. The arithmetic processing circuit 15 outputs Vx and Vy as an image signal V0 subjected to arithmetic shading correction. In addition, when actually reading a similar document, the first transfer control pulse φ of the photoelectric retrieval element 1 is switched from the output φ2 of the frequency divider circuit ( ) to the output φ1 of the clock light generation circuit 4 to enable high-speed operation. It has become. Switch S to switch from φ2 to φl? °
(Do it. In addition, in the above-mentioned 52, the main unit 11 and the processing circuit 1
5 and ab[1g performance method b's were used, but there is no need to be limited to this; 'j'-r digital performance t31 performance 315
You may also use formula. In this case, 1, convert the output of the optical 7n converter Takako 1 into digital data 1a, :me, Δ,,
/ l) Move the transducer off-center. - Instead of C, the D/Δ variable rag 13 + used in the actual example of Figures 1 and 2
aI become depressed. (Moving bed of the invention) As explained in detail, the deviation of the wooden button 1!
i50) From the correction to correct the sensitivity jL, to the shedding correction for each color, note down the coefficients of 10 and 1.
By correcting the image face signal from the photoelectric conversion element using the tT coefficient, accurate Marub 7J no image □□
□You can get information.

[Brief explanation of drawings]

Fig. 1 shows an embodiment of the present invention, and Fig. 11 shows the commercial 1t'+ composition, Fig. 21ii1t shows the cutting shape fui of the switch, and Fig. 3 shows the photoelectric radiation after passing through the IL color filter. Conversion 15 completed output 'l-,'l I! + is a small figure. '1...Photoelectric conversion element 2...-It g small IL system (1 unit 3...differential amplification 11g 4...ri 1-1 output/L, jf145...frequency divider circuit 6 ... Control circuit (° 87 ... rotation) 5 control circuit E) ... Timing circuit 9.10.12 ... Memory circuit 11 ... Heavy equipment 1 Go 3 ... 1) / l＼Hen model 14
・・・Ripple hold circuit

Claims (1)

[Claims] Uniform - Original Notes: Each foul light on the 1st page and the manuscript side is electrically calculated.
&1@ photoelectric converter and the photoelectric converter 1! II! The first correction for uniformizing the output of the photoelectric conversion element by receiving () the refracted light from the uniform-reflective surface by the thread: f stage and corrections specific to each color are recorded in advance 10 times and d3. <The first storage means, the correction coefficients stored in the '1st il iF means, and the correction standards for each color stored in the first storage means are subjected to floating HF processing, and each (B, B1 is equipped with a second correction means for storing correction coefficients for fn, and a second storage means for storing correction coefficients for each color fn. The signal obtained by photoelectrically converting the corresponding color filter) II) is converted to +11. 1. A 1-de C correction device, characterized in that it is configured to store a correction 1 series number C and a correction J stored in the second storage means.