JPH0642715B2 - Image information reader - Google Patents

Description

The present invention relates to an image information reading apparatus that obtains image information from a document by photoelectric conversion means, and more particularly to an image information reading apparatus having a shading correction function.

[Prior Art] Conventionally, a transmitted light image of a transparent color original is converted into three primary colors, for example, R.
Color separation into (red), G (green), and B (blue) is performed, three types of image signals corresponding to the respective color-separated images are obtained from the image sensor, and these three types of image signals are converted into digital image information. An image information reading device that does this is generally known.

[Problems to be Solved by the Invention] However, in the conventional image information reading apparatus of this type, in general, the illuminance unevenness of the illumination system for illuminating the transparent color original or the projection system for projecting the transparent color original onto the image pickup device There is a problem in that the image data that has been read out becomes uneven due to "curl" and the like, and high-quality image data cannot be obtained.

On the other hand, it is known that the read image data is corrected with a predetermined correction value corresponding to the uneven illuminance. However, when the original is read by changing the projection magnification, the uneven illuminance of the projection lens The previous correction value cannot be applied as it is because it changes depending on the magnification.

Therefore, it is conceivable that the illuminance unevenness is measured when the projection magnification is determined and the correction value is determined each time.

However, when cutting out a part of the screen and reading it, or when determining the projection magnification, it is desirable in operation to first project the image on the finder system and visually check the projected image while trimming. As described above, when the image is projected on the finder system, since the transparent original is inserted in the optical path, the unevenness in illuminance cannot be measured, and thus the correction value cannot be determined.

The object of the present invention has been made in view of the above-mentioned problems, and in addition to obtaining accurate image reading data of enlargement and reduction, and obtaining uneven illumination data corresponding to the enlarged / reduced screen, there is uneven illumination. In particular, it is to provide an image information reading device that can obtain high-quality image read image data.

[Means for Solving Problems] In order to achieve this object, in an image information reading device for converting image information of a document into an electric signal by a photoelectric conversion element,
Reading a manuscript: A correction value detecting means for detecting a shading correction value based on the illuminance distribution of mainly infrared light of the illumination light from the optical system; and a photoelectric conversion element for reading the shading correction value detected by the correction value detecting means. An image processing unit for performing shading correction on the obtained image information is provided.

[Operation] In the present invention, the shading correction value based on the illuminance distribution of the illumination light from the illumination optical system and the projection optical system is detected by the correction value detection means. At that time, a shading correction value mainly based on the illuminance distribution of infrared light is detected. Shading correction is performed on the image information read by the photoelectric conversion element in the image processing unit based on the detected correction value.

Embodiments Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows the basic configuration of the embodiment of the present invention.

In FIG. 1, a is an illumination optical system, b is an IR filter inserted in the optical path when a correction value is detected, c is a document, d is a projection optical system, e is a photoelectric conversion element, and f is a correction value detecting means. .
At the time of detecting the correction value, the light emitted from the illumination optical system a and passing through the IR filter b, the original document c, and the projection optical system d is received by the photoelectric conversion element e, and the output of the photoelectric conversion element e is input to the correction value detection means f. A correction value based on the illumination intensity distribution of the transmitted illumination light, mainly infrared light, is calculated and detected. Next, in the image reading of the document c, the shading correction based on the above-mentioned correction value is applied to the output signal of the photoelectric conversion element e by the image processing means g.

FIGS. 2 (A) and 2 (B) show the spectral transmittances of a typical negative film and reversal film, respectively. This figure (A)
Is the spectral transmittance characteristics of the negative film without exposure, this figure (B)
Shows the spectral transmission characteristics of the reversal film before exposure. Here, the horizontal axis represents wavelength and the vertical axis represents transmittance. As shown in this figure (A), (B), in the infrared region, for example 800
It is understood that both the negative film and the reversal film have high transmittance at wavelengths of nm and above. In addition, it has been experimentally confirmed that the transmittance in the infrared region hardly changes depending on the transmittance in the visible region (about 350 to 700 nm) and is high. That is, if attention is paid to wavelengths in the infrared region of 800 nm or more, it is possible to measure the illuminance unevenness on the light receiving surface regardless of the film image information. The embodiment of the present invention utilizes this principle to perform shading correction described in detail below.

FIG. 3 shows a schematic configuration of the film scanner of the embodiment of the present invention.

In the figure, 1 is an illumination lamp for illuminating a film original,
Reference numeral 2 is a condenser lens that collects illumination light, and 3 is a heatproof filter. The lamp 1, the condenser lens 2 and the heatproof filter 3 constitute an illumination system. 4 is a filter changing mechanism described later in FIG. 6 and 5 is a fifth
A shutter mechanism described later in the drawing. Reference numeral 6 denotes a sub-scanning system, which will be described later in FIG. 4, which scans the film original, and sequentially scans the film original in the vertical direction (sub-scanning direction) of the drawing substantially perpendicular to the optical axis. A projection lens 7 forms an image of the transmitted light of the film original on the sensor 11, and has a zoom function capable of changing the projection magnification.

Numeral 8 is a total reflection mirror rotatable about a pivot, which is in the optical path (observed solid line position in the figure) when the finder is observed, and a known drive mechanism, such as a rotary mechanism, is located at the position indicated by the alternate long and short dash line in the figure during film scanning. It is driven by a plunger or the like to evacuate. Reference numeral 9 denotes a focus plate of the finder, which is used by the user to observe the film original. 10 is a photometric sensor patterned on a transparent glass substrate.

The sensor 11 is a line sensor of a self-scanning type such as a CCD, and is arranged at a right angle to the optical axis and in a direction perpendicular to the drawing (main scanning direction) which is 90 ° offset from the scanning direction (sub-scanning direction) of the sub-scanning system 6. There is. Reference numeral 12 denotes a light amount adjusting mechanism such as a diaphragm mechanism and an ND filter that controls (adjusts) the light receiving surface illuminance of the line sensor 11 based on the photometric output of the photometric sensor 10. In this example, the position of the projection lens 7 is set. It is arranged.

In addition, l-l shows an optical axis.

FIG. 4 shows a detailed configuration example of the sub-scanning system 6 of FIG. In the figure, 21 is a scanning unit (carriage) that is instructed so as to be movable in the direction of the arrow (sub-scanning direction), and 22 is a scanning unit 21
A guide rail that supports the arrow in the moving direction of the arrow (sub-scanning direction), 23 is a feed screw that drives the scanning unit 21 by being rotated by a drive motor (26) described later, and 24 and 25 are rails 22 and 23. Is a support portion that supports the base at both ends with respect to a base (not shown).

Reference numeral 26 denotes a drive motor that drives the scanning unit 21 in the direction of the arrow in the drawing by rotating the feed screw, and is a step motor that drives stepwise according to the reading pitch of the sensor 11.
A film original holder 27 is fixed on the scanning unit 21 and moves integrally with the scanning unit 21. 27a and 27b are a pair of glasses of the holder 27, and sandwich the film original between them to enhance the flatness of the film original.

Reference numerals 28, 29, and 30 denote switches for detecting the scanning start position, the center position, and the scanning end position of the scanning unit 21, respectively, and corresponding protrusions 21a, 21b, which are integrally provided on three sides of the scanning unit 21. It is turned on and off (opened and closed) by 21c. That is, the scanning unit 21 is at the start position when the first switch 30 is ON, and the scanning unit 21 is when the second switch 29 is ON.
Is in the center position, and when the third switch 28 is ON, the scanning unit 21 is in the scanning end position. The detection of the central position by the switch 29 is used when observing the entire screen by the finder 9.

FIG. 5 shows the detailed structure of the shutter mechanism 5 of FIG.
In the figure, 31 and 32 are light shielding plates that are rotatably supported about rotating shafts 31a and 32a, and 33 and 34 are rotary plans that rotate and drive the light shielding plates 31 and 32 through the rotating shafts 31a and 32a, respectively. It's a jar. A range AA indicated by a chain double-dashed line in the figure is a screen range of a film original.

When observing the viewfinder, the light blocking plates 31 and 32 are driven outwardly by the rotary plungers 33 and 34,
At the opening position shown by the broken line in this figure, when reading the film original data, the light shielding plates 31 and 32 are driven inward by the rotary plungers 33, 34 and are at the light shielding position shown by the solid line. When the light shielding plates 31 and 32 are in the light shielding position, they are closed except for the slit portion 31b having the width a so that only a part of the film original facing the light receiving portion of the sensor 11 is illuminated. The original part is the light shield plate 31, 32
The light is shielded from light by this, and thereby deterioration of the image quality of the read image data due to ghost flare or the like is minimized. l-l is the same optical axis as in FIG.

FIG. 6 shows a detailed structure of the filter exchange mechanism 4 of FIG. In the figure, reference numeral 35 is a filter holder for holding a color filter or the like inserted in the optical path l-l, which is rotatably supported by a support shaft 35g. The filter holder 35 has a transparent part 35b for observing the viewfinder.
And R (red), G (green), and B (blue) color separation filters 35c, 35d, and 35e, respectively, for measuring shading correction values and detecting dust and scratches on film originals or optical systems. An IR filter (infrared filter) 35f having a visible light cut characteristic is provided.

Reference numeral 35a is a gear (gear) formed on the circumference of the semicircular filter holder 35. A small-diameter gear 36 is driven by the motor 37, and the large-diameter gear 35 that meshes with the gear 36.
Rotate the filter holder 35 via a and
5b and one of the R, G, B and IR filter sections 35c, 35d, 35e and 35f are selectively inserted in the optical path l-1.

In addition, on the side surface of the filter holder 35, the optical path l-l
Pattern electrodes 38a, 39a, 40a, 41a, 42a, 43a for detecting the position of a filter inserted therein are provided. That is, the electrode 43a is associated with the position of the transparent portion 35b, the electrode 39a is associated with the position of the R filter 35c, and the G filter 35d.
The electrode 40a is provided corresponding to the position of, the electrode 41a is provided corresponding to the position of the B filter 35e, and the electrode 42a is provided corresponding to the position of the IR filter 35f. To be done.

Further, brushes 38b, 39b, 40b, 41b, 42b, 43b are arranged corresponding to the electrodes 38a, 39a, 40a, 41a, 42a, 43a, respectively. Now, assuming that the brush 38b, which is always in contact with the electrode 38a, is at the ground level (ground potential), the brush 43b is at the low level when the transparent portion 35b is inserted in the optical path as shown in FIG. , R filter 35c is inserted, the brush 39b becomes low level and G
When the filter 35d is inserted, the brush 40b becomes low level, when the B filter 35e is inserted, the brush 41b becomes low level, and when the IR filter 35f is inserted, the brush 42b becomes low level. It becomes a level.
l-l is the same optical axis as in FIG.

FIG. 7 shows the total spectral sensitivity including the spectral sensitivity of the linear sensor 11 with respect to the spectra of the R, G, B and IR filters 35c, 35d, 35e and 35f of the filter holder 35. Here, the horizontal axis represents wavelength and the vertical axis represents sensitivity. As shown in the figure, when the IR filter 35f is used, the linear sensor 11 photoelectrically converts, particularly at a wavelength in the infrared region of 800 nm or more.

In FIG. 8, B shows an output example of the visible light filter (for example, B filter 35e), and IR shows an output at the same film position of the IR filter 35f. That is, B and IR in FIG. 8 respectively represent the output of one line of the linear sensor 11, and in FIG. 8B, the light and shade of the image on the transparent color film original is clearly shown as the output of the sensor 11. It has been reproduced. On the other hand, the sensor 1 with the IR filter 35f shown in the IR of this figure
The output of 1 is an almost constant output regardless of the magnitude of the image output of the sensor 11 in the B filter 35e shown in B, and since the change in this waveform is considered to be uneven illuminance, uneven illuminance on the light receiving surface of the sensor 11 is considered. Can be measured by the output of the sensor 11 when the IR filter 35f is used.

FIG. 9 shows the circuit configuration of the film scanner of the embodiment of the present invention shown in FIG. In the figure, reference numeral 101 is a control unit for controlling each motor and sensor in accordance with the control procedure as shown in FIGS. Reference numeral 102 denotes a mirror drive unit that controls the drive of the rotary plunger 8a that opens and closes the mirror 8.
Is a shutter controller for driving and controlling the rotary plungers 33, 34 of the shutter mechanism 5, 104 is a filter controller for driving and controlling the motor 37 of the filter exchanging mechanism 4, and 105 is driving and controlling the motor 26 of the sub-scanning system 6. It is a scanning control unit. A sensor driver 106 drives and controls the linear sensor 11. Reference numeral 108 denotes an A / D (analog / digital) converter that sequentially performs analog / digital conversion of the output of the self-scanning type linear sensor 11 such as a CCD.

109 is a calculation memory that calculates a correction value for shading correction from the illuminance unevenness data measured by the linear sensor 11 by inserting the IR filter 35f in the optical path as described below, and stores the calculated correction value, 110 is A correction processing unit that adds shading correction to the image output of the A / D converter 108 based on the correction values stored in the memory 109.

Next, the operation of the embodiment of the present invention will be described in detail with reference to the flow charts of FIG. 10, FIG. 11 and FIG.

Now, when observing the film original with the naked eye through the finder, the mirror 8 is in the optical path of l-1, the center of the film original holder 27 of the sub-scanning system 6 is at the center position of the optical path, and the shutter mechanism 5 is used. The light-shielding plates 31 and 32 are open, and the transparent portion 35b of the filter exchanging mechanism 4 is inserted into the optical path. In this state, the user (operator) confirms the image state of the film original by the image on the focus plate 9 of the finder.

Next, when the start button 112 is pressed and the scanning start signal (start signal) 211 is generated (step S1), the control unit 101
First outputs a mirror drive signal 201 to the mirror drive unit 102, retracts the mirror 8 from the optical path by the rotary plunger 8a (step S2), and then outputs a shutter drive signal 202 to the shutter control unit 103, and a pair of The rotary plungers 33 and 34 drive the shading plates 31 and 32 of the shutter mechanism 5 to the shading positions to shade harmful light such as ghost flare (step S3).

At the same time, the control unit 101 outputs a filter control signal 203 to the filter control unit 104 to selectively insert a color separation filter in the optical path.

First, the filter control unit 104 responds to the filter control signal 203 by the motor 37 until the IR filter 35f is inserted in the optical path, that is, the brush 42b becomes low level.
Is driven (step S4).

When the brush 42b becomes low level, the filter control unit 104
Is a filter replacement end signal that means the end of filter replacement
204 is returned to the control unit 101. In the subroutine shown in FIG. 11 of step S5, when the control unit 101 receives the filter exchange end signal 204 (step S101), it outputs the reading start signal 207 to the sensor driver 106, and the driver 106 responds to this start signal 207. The sensor 11 is driven (step S102). Output signal of the sensor 11 (image signal)
209 is sequentially converted into a digital signal by the A / D converter 108, and is sent to and stored in the arithmetic memory 109 (step S103), and the sensor 11 outputs the output signal 209 by a predetermined number of pixels and finishes reading one line. (Step S10
Four).

The above read storage cycle is repeated a predetermined number of times, for example 256 times, and the output data of the A / D converter 108 is sequentially stored in the memory 10.
Store in 9 (step S105). After that, the average value of the 256 times of data stored as described above by the memory 109 is obtained for each pixel, and the obtained average value is set as the illuminance unevenness data ▲ ▼ of each pixel.
The maximum value () max of ▼ is obtained (step S106).

Then, with the memory 109, for each pixel,
The ratio of the illuminance unevenness data ▲ ▼ of each pixel to the maximum value () max of the illuminance unevenness data of all pixels, that is, the following equation (1)
Then, the correction value Hn for each pixel is obtained and stored (step S107).

Hn = () max / ▲ ▼ …… (1) Hn: correction value for n pixels () max: maximum value of uneven illuminance data ▲ ▼: uneven illuminance data for n pixels Then, proceed to the subroutine of FIG. 12 at step S6. When the control unit 101 receives the filter exchange end signal 204 (step S201), the control unit 101 transmits the scan start signal 205 to the scan control unit 105. When the scanning control unit 105 receives the scanning start signal 205, first, the sub-scanning system (carriage) 6 is moved to the scanning start position,
That is, until the switch 30 turns on, the step motor
26 is driven (step S202). When the switch 30 is turned on, the scanning control unit 105 determines that scanning has ended, and returns a scanning end signal 206 to the control unit 101. At this point, the preparation operation for scanning the film original is completed.

The control unit 101 receives the scan end signal 206 (step S20
3), the reading start signal 207 is output to the sensor driver 106, and the driver 106 drives the sensor 11 according to the starting signal 207. Output signal of the sensor 11 (image signal)
209 is sequentially converted into a digital signal by the A / D converter 108, output by a predetermined number of pixels, and input to the correction processing unit 110 in order. The processing unit 110 sequentially reads out and multiplies the correction value Hn of the corresponding pixel stored in the memory 109 with respect to the output signal from the A / D converter 108, and sequentially outputs it as image read data to the outside (step S204). .

The sensor 11 outputs the output signal 209 for a predetermined number of pixels, and finishes reading one line. Upon completion of reading this one line (step S205), the control unit 101 causes the scan control unit 1 to operate.
The scan control signal 205 is output to 05, and the scan control unit 105 drives the pulse motor 26 by a predetermined pitch in response to the scan control signal 205 to complete the sub-scan for one line of the sub-scanning system 6 ( Step S206).

After that, returning to step S204, the sensor 107 is driven in the same manner as described above, and the image signal (IR signal) of one line is read. When the reading processing operation of steps S204 to S206 described above is repeated for a predetermined cycle (for one screen) (step S20
7) The reading of IR image data is completed.

Then, return to the main routine and proceed to step S7,
The control unit 101 uses the filter control signal 2 to replace the filter.
The filter control unit 104 is operated by 03 to drive the motor 37 until the R filter 35c is positioned in the optical path l-1, that is, the brush 39b becomes low level.

After the R filter 35c is selected in this manner, the process proceeds to step S8, and the R screen data is read by repeating the same processing cycle (steps S201 to S208 in FIG. 12) as the IR screen reading described above.

The G screen data and the B screen data are also read from the linear sensor 11 in the same manner as described above (steps S9, S10, S11, S1).
2) Finish the full-screen reading of the film original.

After the completion of this one-screen reading, the control unit 101 operates the scan control unit 105 by the scan control signal 205 to move the sub-scanning system 6 to the center position of the sub-scanning by the rotation of the motor 26 (step S13), and the driving is completed. After that, after the switch 29 is ON,
The filter control signal 203 operates the motor 37 via the filter control unit 104 to insert the transparent portion 35b into the optical path (switch S14), and the mirror drive signal 201 operates the mirror drive unit 102 to move the mirror 8 in the optical path. (Step S15), the shutter drive signal 202 operates the rotary plungers 33, 34 via the shutter controller 103 to open the light shielding plates 31, 32 (step S16). Through the above processing, a series of screen reading processing operations for film originals are completed.

[Effects of the Invention] As described above, according to the present invention, focusing on spectral transmission characteristics in infrared light, shading data is measured with transmitted infrared light, and a correction value is calculated based on the data, Since the read image data is corrected based on the correction value, it is possible to correct even if there is a change in the illuminance unevenness due to changes in the projection magnification or trimming, and the film original is inserted in the optical path. In addition, it is possible to measure the illuminance unevenness, to correct the sensitivity unevenness of each pixel of the image sensor, and to correct the aging of the illumination system, especially the illumination lamp.

And so on.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the basic structure of an embodiment of the present invention, and FIGS. 2 (A) and 2 (B) are characteristic curve diagrams showing the spectral transmission characteristics of a film without exposure. 3 is a schematic diagram showing a schematic configuration of the film scanner of the embodiment of the present invention, FIG. 4 is a perspective view showing a configuration example of the sub-scanning system 6 of FIG. 3, and FIG. 5 is a shutter mechanism 5 of FIG. FIG. 6 is a perspective view showing a configuration example, FIG. 6 is a perspective view showing a configuration example of the filter exchanging mechanism 4 of FIG. 3, and FIG. 7 is a characteristic diagram showing spectral sensitivity of R, G, B, and IR filters. FIG. 8 is an output waveform diagram showing an output example of the sensor 11 at the same position of the visible light filter and the IR filter film, FIG. 9 is a block diagram showing the circuit configuration of the color scanner of FIG. 3, FIG. 10, FIG. And FIG. 12 is a flow chart showing the control procedure of the control unit 101 in FIG. 1 ... Lamp, 2 ... Condenser lens, 3 ... Thermal filter, 4 ... Filter exchange mechanism, 5 ... Shutter mechanism, 6 ... Sub-scanning system, 7 ... Projection lens, 8 ... Total reflection mirror, 9 ... Focus plate, 10 ... Photometry Sensor, 11 ... Sensor, 12 ... Light intensity adjustment mechanism, 26,37 ... Motor, 27 ... Film original holder, 31,32 ... Shade plate, 35 ... Filter holder, 101 ... Control section, 102 ... Mirror drive section, 103 ... Shutter controller, 104 ... Filter controller, 105 ... Scan controller, 106 ... Sensor driver, 108 ... A / D converter, 109 ... Arithmetic memory, 110 ... Correction processor.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shigeki Yamada 770 Shimonoge, Takatsu-ku, Kawasaki-shi, Kanagawa Canon Inc. Tamagawa Plant (72) Inventor Go, Kobayashi 770 Shimonoge, Takatsu-ku, Kanagawa At the Tamagawa Plant (72) Inventor Makoto Katsuma 770 Shimonoge, Takatsu-ku, Kawasaki City, Kanagawa Prefecture Canon Inc., Tamagawa Plant

Claims (1)

[Claims] 1. A) An image information reading device for converting image information of an original into an electric signal by a photoelectric conversion element, b) Based on an illuminance distribution of mainly infrared light of illumination light from an optical system for reading the original. Correction value detecting means for detecting the shading correction value, and c) image processing means for performing shading correction on the image information read by the photoelectric conversion element by the shading correction value detected by the correction value detecting means. An image information reading device characterized by being provided.