JPH0265374A - Color picture reader - Google Patents

Abstract

PURPOSE:To easily execute conversion to optimum picture data by calculating difference between the reference value of a reference look-up table and the value of a digital picture signal before the conversion and setting a look-up table, for which the reference look-up table is shifted only for the difference, or sending a value, for which the difference is added to the digital picture signal, to the look-up table. CONSTITUTION:The difference (correcting value) between the output value of a photo-detecting element 3068 and the reference value of a reference look-up table R is obtained in the exposure quantity of a standard negative film and samely, processing is executed to the output value of a G and the output value of a B. Then, the respective correcting values are obtained. When picture data are processed, the above mentioned correcting values to be obtained are sent from a controller 3039 to a look-up table converting circuit 3031. Then, while the above mentioned correcting values are added to the respective R, G and B picture data, the conversion is executed by the look-up table. Thus, the converted picture data are outputted through an interface circuit 3038.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a color image reading device, and particularly to a color image reading device that reads a transparent original such as a 35 mm color film as image data using a photoelectric conversion element such as a CCD line sensor. Regarding equipment.

[Prior Art] Conventionally, this type of image reading apparatus generally performs briscanning (pre-reading scanning) of a document in order to detect the average density of the document. Then, depending on the average density value of the document detected during this briscan, the lamp light intensity of the document illumination light source is changed, or the lens aperture of the imaging lens is changed to find the optimum density. The document is being read and scanned in this state.

[Problem to be solved by the invention] However, in the conventional device as described above,
When reading images from films with different exposure conditions such as underexposure and overexposure, such as photographic film, the exposure range that can be applied to these films is extremely narrow just by processing corresponding to the lens aperture and the amount of light. In addition, when reading film originals at high speed using a solid-state image sensor such as a CCD line sensor, if you try to handle film originals that have exposure changes within a range of ±2 steps in EV value (exposure value), the light amount requires a change of more than 6 times. Therefore, the light source becomes large, and even if a Kohler illumination optical system or a heat ray absorption filter is used, the effect of heat on the film document is large, and there is a high possibility that the film will be deformed. Therefore, in reality, there is a problem in that it is not possible to deal with film originals having different exposure amounts by controlling only the light amount.

Furthermore, since the characteristics of different films, such as 35III11 photographic film, vary greatly depending on the type of film, there is a problem in that the reference table of the look-up table must be a table specific to that film. In addition to this, if the aforementioned underexposure or overexposure of the film is added, the light intensity and lens aperture will change, and if this cannot be handled, it is necessary to select a table that can handle it from among the unique tables. was there.

For this reason, the conventional bag d has the disadvantage that a large number of cheap pools must be prepared in advance depending on the type of film and the degree of underexposure and overexposure for the film.

An object of the present invention is to eliminate the above-mentioned drawbacks, and to prepare as many look-up tables as there are film types according to the film type, this requires a relatively small memory capacity for the look-up tables. It is an object of the present invention to provide a color image reading device capable of responding subtly and appropriately depending on the degree of overexposure or underexposure of a film.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an image sensor that reads a color image formed by an optical system as color data, and an A that converts the output of the image sensor into a digital signal.
/D conversion means, a reference lookup table storing conversion data for output density conversion, and a difference between the reserved value of the digital signal obtained from the A/D conversion means and the reference value of the reference lookup table as a correction value. A/D conversion is performed using a correction value calculation means to calculate, a table conversion means to set a lookup table in which the contents of the reference lookup table are shifted entirely by the correction value calculated by the correction calculation means, and the lookup table. The apparatus is characterized by comprising a density correction means for adjusting the density of the output of the means.

In addition, in order to achieve the above object, the present invention includes an image sensor that reads a color image formed by an optical system as color data, and converts the output of the image sensor into a digital signal.
/D conversion means, a lookup table storing conversion data for output density conversion, and calculating the difference between the average value of the digital signal obtained from the /D conversion means and the reference value of the lookup table as a correction value. a correction value calculation means; an addition means for adding the correction value calculated by the correction value calculation means and the value of the digital signal output from the A/D conversion means; and a lookup table using the addition result of the addition means as converted data. The apparatus is characterized in that it is equipped with a density correction means for adjusting the output (by 4 degrees).

[Function] With the above configuration, the present invention calculates the difference between the reference value of the reference lookup table and the value of the digital image signal before conversion, and creates a lookup table in which the reference lookup table is shifted by the difference. Since the value obtained by adding the difference to the digital image signal is sent to the lookup table, it is only necessary to store the lookup table that serves as a reference for the number of film types, and the exposure For images where the amount is under or over,
By simply shifting the lookup table or shifting the image data, it is possible to easily convert the image data to the optimal image data.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIGS. 1(A) and (8) show the basic configuration of an embodiment of the present invention. In this figure (^), A is an image sensor that reads a color image formed by an optical system as color data. B is an A/D conversion means that converts the output of the image sensor A into a digital signal. C is a reference lookup table that stores conversion data for output density conversion. D is A
This correction value calculation means calculates the difference between the average value of the digital signal obtained from the /D conversion means B and the reference value of the reference lookup table as a correction value. Reference numeral E denotes a table conversion means for setting a lookup table F in which the contents of the reference lookup table are entirely shifted by the correction value calculated by the correction value calculation means. G is a density correction means that uses the lookup table F to adjust the density of the output of the ^/D conversion means B.

In addition, in Fig. 1 CB), A is the image sensor, and B is the A/
D conversion means, C' is a look-up table, and D' is correction value calculation means. H is the correction value calculation means D' and A/
Adding means adds the value of the digital signal outputted from the D converting means B, and (2) is a density correcting means that sends the addition result of the adding means H to the look-up table C' as data to be converted and adjusts the output density.

FIG. 2 shows a specific circuit configuration of an embodiment of the present invention.

In this figure, 3001 is a light source (lamp) for illuminating a transparent original, 3002 is a heat ray absorption filter that removes heat rays from the light rays from the light source 3001, and 3003 is a filter 3.
This is an illumination optical system that converts illumination light passing through 002 into a parallel light beam. 3004 is a sub-scanning drive table that moves the transparent original in the sub-scanning direction; 3005 is a rotating table that rotates the transparent original; 300
6 is a film holder for storing a transparent original, and 3007 is a transparent original such as a 35 mm photographic film. 30
08 is a movable mirror that switches the optical path of the light beam (original image) transmitted through the transparent original 3007; 1009 is a mirror that deflects the optical path of the original image; and 301O is an imaging lens that forms the original image that has passed through the mirror 3009. .

3011 is a projection lens for projecting the original image reflected by the movable mirror 3008; 3012 is a mirror that deflects the optical path; 3013 is a mirror that deflects the same optical path; 3014
is a screen serving as a monitor on which the original image that has passed through the mirror 3013 is projected. 3015 is the screen 3014
3016 is the screen 3
014 is a touch panel that manually controls the trimming area.

3017 is a lamp holding member that supports the light source 3001. 3018, 3019, and 3020 are CCD positioning mechanisms, 3021 are three-color separation prisms that separate the transparent original image formed by the imaging lens 3010 into three colors of R, G, and B, and 3022, 3023, and 3024 are prisms, respectively. CC using a CCO (charge-coupled device) array that photoelectrically converts the original image of each color separated by 3021
This CCD line sensor is a D line sensor, and the reading position can be finely adjusted by the corresponding CCO alignment mechanism 3018, 3019, 3020.

3025 is a CCD line sensor 3022, 3023.
Amplify the analog output of 3024 and convert it to ^/D (analog/
3026 is an adjustment (g generation source) that generates a standard signal for adjustment to the analog circuit 3025; 3027 is an analog circuit unit 3025 that performs digital) conversion;
3028 is a shading correction circuit that performs shape ink correction on the output signal of the dark correction circuit 3027; 3029 is the output of the shading correction circuit 3028; A pixel shift correction circuit 3030 corrects pixel shift in the main scanning direction with respect to the signal, and a pixel shift correction circuit 3030 outputs the R, G, and B signals that have passed through the pixel shift correction circuit 3029, for example, Y (yellow), M (magenta) depending on the output device. , C (cyan). Further, 3031 is a look-up table (LOT) conversion circuit that performs LOG conversion and γ conversion of signals.

3032 is a minimum value detection circuit that detects the minimum value of the output signal of the lookup table conversion circuit 3031; 3033 is an under color removal (O
A lookup table (L
OT), 3034 is a lookup table 3031
3035 is a masking circuit that performs masking processing on the output signal of the masking circuit 3034, and 068 circuit (undercolor removal circuit) that performs undercolor removal processing on the output signal of the masking circuit 3034 based on the output value of the lookup table 3033. be.

3036 is a density conversion circuit that converts the recording density of the output signal of the OCR circuit 3035 into a specified density, and 3037 is a scaling processing circuit that converts the output signal of the density conversion circuit 3036 to a specified scaling factor.

3038 is an interface circuit (I/F) that transmits signals between a printer or input/output terminal (not shown) and this device;
3039 is a controller that controls the entire device, and inside the controller 3039 there is a CPU (central processing unit) such as a microcomputer, a ROM (read only memory) in which processing procedures are stored in program form, and a data storage. RAM used as a work area
(random access memory), etc.

3040 is an average value detection circuit that detects the average value of the output values manually input from the scaling processing circuit 3037 through the interface circuit 3038 and the controller 3039; 3041 is an operation unit that issues instructions to the controller 3039; and 3042 is a control unit for the controller 3039. This is a display unit that displays the status, etc.

3043 is a lens aperture control unit that controls the aperture of the imaging lens 301O, 3044 is a lens distance ring control unit that adjusts the focus of the imaging lens 3010, and 3045 is a mirror drive unit that drives the movable mirror 3008. 3046
3047 is a trimming frame control unit that controls the trimming frame display 3015 and a touch panel control unit that controls the touch panel 3016. 3048 is a rotary table rotation control unit that drives and controls the rotary table 3005; 3049 is a sub-scan control unit that controls scanning of the sub-scan drive table 3004; 3050 is a lamp light amount control circuit that controls the light amount of the light source (lamp) 3001; 3051; is a lamp position driving source that adjusts the position of the light source 3001 via the lamp holding member 3017.

3052 is a timing generator that generates a timing signal (clock) under the control of the controller 3039; 3053 is a bus that connects each of the above-mentioned control units and processing circuits with the controller 3039; 3054 is a data line for output equipment; 3055 is an output Synchronization signal line for equipment,
and 3056 are communication lines.

Next, the operation of each part will be explained.

The light source 3001 is a light source such as a halogen lamp, and the light emitted from the light source 3001 is passed through a heat absorption filter 30.
02 and an illumination optical system 3003, a transparent original 3007 such as a 35 mm photographic film placed on a film holder 3006 is illuminated. By switching the optical path by a movable mirror 3008, the image of the transparent original 3007 is transmitted onto the screen 3014 through the projection lens 3011 and mirrors 3012 and 3013, or through the mirror 3009, the imaging lens 301O1, and the three-color separation prism 3021. CCD line sensor 30
22 to 3024.

In the case of the above-mentioned mode (■), the CCD line sensors 3022 to 3024 are connected to the timing generator 3052.
The output signals of each CCD line sensor are input to an analog circuit 3025. The CCD positioning mechanisms 3018 to 3020 each
This is for registering the CD line sensors 3022 to 3024 with the three-color separation prism 3021, and needs to be adjusted at least once. The analog circuit 3025 is composed of an amplifier and an A/D converter, and converts the signal amplified by the amplifier into the A/D converter in synchronization with the timing clock for ^/D conversion output from the timing generator 3052. Perform A/D conversion.

Next, RlG, B output from the analog circuit 3025
A dark processing circuit 3027 applies dark signal level correction to each digital signal, a shading correction circuit 3028 performs shading correction in the main scanning direction, and a pixel deviation correction circuit 3029 corrects pixel deviation in the main scanning direction. , for example, by shifting the write timing of a FIFO (first-in, first-out) buffer.

Next, the color conversion circuit 3030 performs color correction of the color separation optical system 3021, and converts the R, G, and B signals into Y, M, and C color signals depending on the output device.

1, convert to Q color signal. The next lookup table conversion circuit 3031 converts the luminance linear signal into LOG or performs arbitrary γ conversion by referring to a table.

Reference numerals 3032 to 3037 constitute image processing circuits for outputting images in four colors, Y, M, C, and BK (black), which are mainly used in printers such as color laser copying machines. Here, the minimum value detection circuit 3032, masking circuit 3034, lookup table 3033, and υC
The combination of the R circuit 3035 performs printer masking and ucR (undercolor removal).

Next, the density conversion circuit 3036 performs table conversion of each density signal, and the scaling processing circuit 3037 roughly performs scaling processing in the main scanning direction.
M', C', 8K" signal interface circuit 3038
The data is sent to the output device's printer via the . The interface circuit 3038 is connected to a data line 3054 for the output device, a synchronization signal line 3055, and a control command communication line such as R5232C, and also communicates with a general computer (for example, a personal computer) via a communication line 3056. A3 is possible.

On the other hand, the lamp position driving source 3051 is the lamp 305 as a light source.
This is for adjusting the lamp position when converting 1, and the lamp 3001 is positioned manually or automatically in accordance with the manual key operation on the operation unit 3041. The lamp light amount control section 3050 and the lens aperture control section 3043 are C
The amount of light received by the image projected onto the CD line sensors 3022 to 3024 is adjusted. Further, the mirror drive unit 3045 controls the movable mirror 3008 and performs optical path conversion to switch whether to guide the image of the transmission thickness fJ% 3007 to the screen 3014 or to the CCD line sensors 3022 to 3024.

In the case of mode (2) in which an image of the transparent original 3007 is projected onto the screen 3014, a trimming frame display controller 3046 displays a trimming area in order to instruct trimming of the image displayed on the screen 3014. 3015, and a touch panel control unit 3047 controls a touch panel 3016 that manually controls the trimming area.

Further, the lens distance ring control unit 3044 controls the imaging lens 3
By controlling the distance ring of 010, the CCD line sensor 302
The images projected on 2 to 3024 and the screen 3014 are focused. The adjustment signal generation source 3026 generates a signal manually input as a standard signal when adjusting the analog circuit 3025.

Next, the overall control operation of this apparatus will be explained with reference to the flowchart in FIG.

A/D Conversion Means It is assumed that the control procedure in this flowchart is stored in the ROM inside the controller 3039.

Preparation operation: When the N source switch (not shown) is turned on, the controller 3039 initializes each part (step S1) and enters a state of waiting for a command manually input from an external device or from the operation unit 3041 via the interface circuit 3038. . In this state, when the film holder 3006 with the transparent original 3007 mounted thereon is set on the rotating table 3005, the light source 3001 illuminates the heat ray absorption filter 300.
02 and an illumination optical system 3003 including a condenser lens, etc.
The image of the transparent original illuminated through the movable mirror 300
8 and projection lens 3011 and mirror: 1012, 301
3 and projected onto a screen 3014.

Transparent originals 3007 have image orientations of portrait and landscape orientation, but if you want to rotate the image and project it, you can rotate the image from an external device via the interface circuit 3038 or from the operation unit 3041 to the controller 3039. When the rotation is instructed (step S2), the controller 30
39 is a rotary table rotation control unit 3048 via a bus 3053
A rotation control command is sent to the rotary table 3005 to rotate the rotary table 3005 (step S3). At this time, since the film holder 3006 is fixed to the rotating table 3005, it rotates together with the rotating table 3005. In this manner, when the transparent original 3007 is rotated, the image projected onto the screen 3014 is also rotated.

Next, if you want to trim the image, use the operation section 3041.
When trimming is instructed to the controller 3039 from an external device or from an external device via the interface circuit 3038 (step S4), the controller 3039 sends a trimming information input command to the touch panel control unit 3047, and the touch panel control unit The trimming information input to the controller 3034 is taken into the controller 3039 via the bus 3053, and the controller 3039 sends trimming frame control information created based on the imported trimming information to the trimming frame display control unit 3046 via the bus 3053. to display the trimming area (step SS).

Next, from the operation unit 3041 or the interface circuit 3
When the external device instructs the controller 3039 to start image reading via 038, image reading starts.
This is carried out according to the following procedure (step S6).

Optical path switching: First, the controller 3039 outputs a drive control signal to the mirror drive unit 3045 to urge the movable mirror 3008, so that the image of the transparent original 3007 is transferred by the mirror 3009 and the imaging lens 301O via the three-color prism 3021. Each CCD line sensor 3022-3
024 (step S)
7).

Dark correction signal set secondary, dark correction circuit 3027
In order to set the dark correction information to
03g, the lamp light amount control circuit 3050 is controlled to turn off the lamp, or the sub-scanning control unit 304
9 to move the sub-scanning drive stand 3004 to a light-shielding position where each CCD line sensor 3022 to 3024 is shielded from light (before step S8). Next, the dark correction circuit 3027 is controlled by the controller 3039, and the dark correction circuit 3027 is controlled based on the signal that is converted into a digital signal and outputted via the analog circuit 3025.
A dark correction signal is set up (after step S8).

Shading correction data set: Subsequently, each CCO line sensor 3022-3024 is illuminated by illumination light.

Step S9) of moving the sub-scanning drive base 3004 to the exposure position where % is exposed, the lamp light amount control circuit 3050 adjusts the lamp tip to an appropriate brightness, and the dark correction circuit 302
Shading correction data is manually set in the shading correction circuit 3028 using the dark-corrected signal in step 7 (step 510).

AE (automatic exposure adjustment), then controller 3039
The color conversion circuit 3030, lookup table conversion circuit 3031. Masking circuit 3034, OCR circuit 3
035, density conversion circuit 3036, scaling processing circuit 3037
In step 511), the average value is detected for the raw data manually input to the controller 3039 via the interface circuit 3038 while performing sub-scanning at high speed. The circuit 3040 is used to detect the average value (step 512), and the lamp light amount control circuit 3050 is controlled to adjust the brightness of the light source 3001 so that the detected average value approaches a certain level (step 513). CC by changing the aperture of the imaging lens 301O or by controlling the lens aperture control unit 3043 to change the aperture of the imaging lens 301O.
The amount of light from the D line sensors 3022 to 302 is adjusted (step 514).

AF (auto focus) secondary, dark correction circuit 30
The signal subjected to dark correction by 27 is input to the controller 3039 via the interface circuit 3038 with the subsequent processing circuit set to through mode, and the lens distance ring control unit 304 uses the information of the input signal.
4 to focus the imaging lens 301O (
Step 515).

After the selection, a pixel shift correction amount is set in the pixel shift correction circuit 3029 (step 516). In addition, the color conversion circuit 3
Select the type of color conversion for 030, and select f! of the lookup table for lookup tables 3031 and 3033. Select type Ii, select the type of masking for the masking circuit 3034, and select u for the OCR circuit 3035.
The presence or absence of CR is selected, the unique type of density conversion is selected for the density conversion circuit 3036, and the type of scaling and sharpness is selected for the scaling processing circuit 3037 (step 517).

Furthermore, the lamp light amount control circuit 3050 controls the lamp light amount to be appropriate, sends the sub-scanning speed and trimming information to the sub-scanning control unit 3049, moves the transparent original 3007 to the sub-scanning start position, and makes it standby (step 518
).

In the operation based on the reading start command from the data output Al1 creation unit 3041 (step 519), a start command is issued to the output device (not shown) via the interface circuit 3038 (step 520), and the sub-reading is performed based on the synchronization signal from the output device. Scanning is started (step 522), an image is captured while being synchronized with the output device, and the processed image data is output via the interface circuit 3038 (step 523).

Data output B: In the reading operation based on the reading start command via the interface circuit 3038 (step 519
), reports the completion of preparation to the output device (not shown) via the interface circuit 3038 (step 521), starts sub-scanning based on the synchronization signal from the output device (step 522), captures images while being synchronized with the output device Then, the processed image data is output via the interface circuit 3038 (step 523).

Next, the control operation that constitutes the central part of the present invention will be explained in more detail.

In the step 511 fi filling procedure in FIG. 3 described above,
As described above, the controller 3039 controls the lamp light amount control circuit 3050 to turn on the lamp 300, and the color conversion circuit 3030. Lookup table conversion circuit 30
31. Masking circuit 3034. IC1 circuit 3035
゜Density conversion circuit 3036. and variable magnification processing circuit 3037
is controlled to be in a through mode (input data is output as is), and raw data is manually input to the control roller 3039 via an interface 3038 while sub-scanning the film original 3007 at high speed. This raw data is data for 256 arbitrary lines near the center of the film original film [3007], and is data after dark processing and shading processing.

In the processing procedure of the next step S12, the following formula (
1) Calculate the average value Y given by.

Y=0.3π10 0.6110.1T...
- (1) Here, R, G, and B are average values of R data, G data, and B data of each raw data. In the next steps 513 and 514, the lamp light amount control circuit 3050 is controlled to change the brightness of the light source 3001 so that this value Y approaches a certain reference level, or the lens aperture control section 3043 is controlled to take an image. By changing the aperture of the lens 3010, the CCD line sensors 3022 to 30
Adjust the exposure amount of 24. If the aperture of the imaging lens 301O is changed, the process returns to step 510, the shading data is reset, and the same process as described above is performed.

However, in most cases, underexposure and overexposure of the film original 3007 cannot be sufficiently corrected even by the above-mentioned lamp light amount operation or lens aperture operation. In order to be able to correct this, in the embodiment of the present invention, the lookup table correction 37(s) of the lookup table conversion circuit 3031 is determined as described below.

R of the reference lookup table of the lookup table conversion circuit 3031 for mts exposure of a certain film
, G, 8 curves are shown in FIG.

Here, the horizontal axis is input data, and the vertical axis is output data.

Further, the reference levels of R, G, and B of this standard lookup table are set to 200.

In contrast, the underexposed film original 3007
is blisscanned, and the value of Y at this time (average value) is determined. FIG. 4 shows an example of Y=125. The difference between Y and the reference level L at this time is defined as a correction amount S.

That is, 5=Y-L...(2) and correct the values of the reference lookup table RGB! By using R', G', and B' added by iS, an underexposed film is dealt with.

Therefore, in the embodiment of the present invention, the lookup table conversion circuit 3031 for film originals such as underexposed
The lookup table setting is performed according to the control procedure shown in the flowchart of FIG.

First, after the process of step 510 in FIG. 3 is completed, the program enters this subroutine, sets the film J] 13007 (step 531), and reads line data for arbitrary 256 lines (step 532). The average value detection circuit 3040 is used to perform the above (1) on the read raw data.
The value of Y is calculated based on the formula (step 533), and the calculated value of Y is compared with the reference level L (step 534).

If the value of Y and the value of L are approximately equal, the standard table is set in the lookup table 3031 (step 535), and the process proceeds to step 515 in FIG.

However, when the value of Y and the value of L are different, this value Y
Either control the lamp light amount control circuit 3050 to change the brightness of the light source 3001 so that the brightness approaches that reference level L, or
Alternatively, the lens aperture control unit 3043 is controlled to change the aperture of the imaging lens 3010 (step 535);
If the aperture of the imaging lens 301O is changed here (step 537), the process of step S10 in FIG. 3 is executed to reset the shading data (step 5).
38), the process returns to step 5e11 and performs the same process as described above.

On the other hand, in step 536, the lamp light amount control circuit 30
50 to change the brightness of the light source 3001, the line data for any 256 lines mentioned above is read (step 539), and the average value detection circuit 3040 is used for the read raw data to calculate the above value. The value of Y is calculated based on the equation (1) (step 540), and the correction amount S is calculated based on the above equation (2) using the calculated value of Y and the reference level L (step 541). Next, set the lookup table of the lookup table conversion circuit 3031 while adding the calculated correction fXS to the value of the standard table (step 542), step 5 in FIG.
Proceed to step 15.

In this way, the selected lookup table of the lookup table conversion circuit 3031 is a table shifted by the correction amount S from the reference table for the number of film types.

Next, other embodiments of the present invention will be described.

In the embodiment described above, the correction amount S is added to the reference lookup table as the lookup table to be set,
The table is set.

In contrast, the following embodiment adds the correction fiS to the data read from the film original 3007, and uses the lookup table of the lookup table conversion circuit 3031 as a reference lookup table to achieve the same effect as the previous embodiment. It is intended to have the following. Moreover, this correction amount S is set based on a detection value of a sensor other than the operation sensor.

Below, with reference to FIGS. 6 to 10, g\
Let me explain the details.

FIG. 6 shows the circuit configuration of another embodiment of the invention described above.

In this figure, the parts that differ from Figure 2 are listed as 30.
59 is a buffer memory corresponding to the pixel shift correction circuit 3o29 in FIG. 2, 3060 is the entire image sensor, and 3061 is R.
CCD line sensor with color separation filters, 306
2 is a CCD line sensor with a G color separation filter;
3063 is a CCD line sensor having a B color separation filter. Also, 3064 is a CCD line sensor 30
61 to 3063 are CCD alignment mechanisms that perform alignment, 3065 to 3067 are CCD line sensors 3061
This is a drive signal output from the timing generator 3052 to drive each of the timing generators 3063 to 3063. 3068 is a light receiving element provided on the image sensor 3060 to obtain the correction value S. The rest of the structure is the same as that of the previous embodiment shown in FIG.

The image sensor 3060 is a 3-line line sensor 3061~
3063, each line sensor 3061 to 30
63 are independently driven by drive signals 30G5 to 3067 output from the timing generator 3052. Further, each of the line sensors 30B1 to 3063 is capable of capturing R, G, and B color separated images using respective on-chip color filters.

The buffer memory 3059 stores each line sensor 3061 to 3.
This is a delay memory for correcting positional deviation in the sub-scanning direction in 063, and is configured using, for example, several FIFO memories. The amount of delay for each color is controller 3
039 in advance according to the sub-scanning speed.

The basic operation of this embodiment is the same as that of the embodiment shown in FIG. 2, but the flowcharts of FIGS. Explain with reference to.

First, the processing operation corresponding to step Sll-514 in FIG. 3 will be explained. In step 1 of FIG. 3, the controller 3039 controls the lamp light amount control circuit 3.
050, lights up the lamp 3001, dark correction circuit 3027, shading correction circuit 3028, pixel shift correction circuit, lookup table conversion circuit 303
1. Masking circuit 3034, [ICR circuit 3025,
The density conversion circuit 3036 and the magnification processing circuit 3037 are all controlled to be in the through mode (manual data is output as is), and the original is set so that the film original 3007 is in the center position.

Next, the subroutine shown in FIG. 7 is entered, and step 551 is entered.
At this point, data D' from the light receiving element 3068 is taken into the controller 3039 via the interface 3038. As shown in FIG. 8, this light receiving element 3068 is designed so that it can averagely measure light around the center of the film 3007 and can measure each of R, G, and B lights.
A silicon photodiode with color separation filters is used.

Next, the lamp light 1IIJ control circuit 3050 is controlled to change the brightness of the light source, or the lens aperture control section 3043 is controlled so that the average value D' of this data D' approaches the reference value L'. By changing the aperture of the projection lens 301O, the CCD line sensors 3022 to 30
Adjust the exposure amount to 24 (steps S52, S53
．． 554). When the aperture of the projection lens 301O is changed, shading data is reset before image reading (steps S55 and 556).
However, when the amount of light is maximum and the lens aperture is wide open, if the above data value D' is short of the above reference value L', the correction amount S' is calculated and the correction amount S
' to easily obtain optimal image data (steps 557, 558, 55Q) - In other words, the light receiving element 30 read in step 551
The output of 68 is the output of 3 trees of R, G, B each, i, l,
, o l , , o l 8, and the transmission average densities D'R and D'G of RlG and B, respectively.

0'6 is determined in step 551.

For example, when reading a 35 mm negative film with a wooden device, the output values D' R of R, G, and B of the light receiving element 3068 are
, D' o, D' a are 1023 when the concentration is; and are zero when the concentration is 3.0, so that the gain of the amplifier in the analog circuit 3025 is adjusted.

Then, from the output value of this light receiving element 3068, for example, the average transmission density DR of the R output value DJ7 is determined by the following equation (3).

As a result, the exposure amount of a standard negative film can be determined from the graph shown in FIG.

In other words, it can be considered that the actual image data is distributed around this exposure amount. Therefore, the difference S'S' between the output value D'9 of the light receiving element 3068 at this exposure amount, that is, D' n, and the reference value L' R of the reference lookup table R. = L'R-D' R... (4) is the correction ff
It becomes l S' p+.

Further, similar processing is performed on the output value D' of G and the output value D' of B to obtain a correction value srG.

Find sj 6. In step 559 of FIG.
As described above, the values of S' R, S' G, and S' are determined, and the process of detecting the detected value of the correction value is completed.

Next, operations corresponding to steps 519 to S23 in FIG. 3 will be explained.

In the operation based on a reading start command from the operation unit 3041 (step 519), a start command is issued to the output device (not shown) via the interface circuit 3038. In step 520), sub-scanning is performed based on a synchronization signal from the output device. Start (step 522).

In this sub-scanning, the image is captured while being synchronized with the output device, and the processed image data is sent to the interface circuit 3038.
(step 523).

When processing the image data in step S23 described above, the correction value S' R obtained in step S59 of FIG.
, S' G, S' a to the controller 303'lh
) to the lookup table conversion circuit 3031, and R
, G, and B each image data S'□ sj G.

While adding sl 6, a look-up table conversion as shown in FIG. 1O is performed. The image data thus converted is output via the interface circuit 3038.

In the embodiment described above, a light receiving element is used separately, but it goes without saying that an image reading sensor may also be used.

(Effects of the Invention) As explained above, according to the present invention, the difference between the reference value of the reference lookup table and the value of the converted digital image signal is calculated, and the reference lookup table is adjusted by the amount of the difference. Since the shifted look-up table is set, or the value obtained by adding the difference to digital image No. 78 is sent to the look-up table, the look-up table that serves as a reference for the number of film types is stored. For images with underexposure or overexposure, you can easily convert them to optimal image data by simply shifting the lookup table or shifting the image data. It will be done.

[Brief explanation of the drawing]

Figures 1 (A) and (B) are block diagrams showing the basic configuration of an embodiment of the present invention, Figure 2 is a block diagram showing the circuit configuration of an embodiment of the present invention, and Figure 3 is a block diagram showing the circuit configuration of an embodiment of the present invention. Flowchart showing the overall operation procedure of the embodiment of the invention; FIG. 4 is a graph showing an example of data conversion by lookup table conversion in the embodiment of the invention shown in FIG. 2; FIG. 5 is a graph showing the embodiment of the invention shown in FIG. 2. 6 is a block diagram showing the circuit configuration of another embodiment of the present invention. FIG. 7 is a flowchart showing the operation procedure of the main part of the embodiment of the present invention shown in A detailed flowchart, FIG. 8 is a Ume-style diagram showing an example of a schematic configuration of the light-receiving element shown in FIG. 6, FIG. 9 is a graph of a characteristic curve showing an example of the relationship between film exposure and density, and FIG. 7 is a graph showing an example of data conversion by lookup table conversion in the embodiment of the present invention shown in FIG. 6; 3001... Light source (lamp), 3004... Sub-scanning drive stand, 3005... Turntable, 3007... Transparent original, 3008... Movable mirror 3010... Imaging lens, 3014... Screen , 3015...Trimming frame display device, 3016...Touch panel, 3018.3019.3020...CCD alignment mechanism, 3021...3 color separation prism, 3022.3023.3024...CCD line sensor, 3031... Lookup table change I^ circuit,
3038... Interface circuit, 3039... Controller, 3040... Average value detection circuit, 3043... Lens aperture control section, 3044... Lens distance ring control section, 3050... Lamp light amount control circuit, 3061.3062.3063...CCI) line sensor, 3068...light receiving element. Figure 1 (A) Figure 4 Figure 1 (B) Figure Figure Figure

Claims (1)

[Scope of Claims] 1) An image sensor that reads a color image formed by an optical system as color data, an A/D converter that converts the output of the image sensor into a digital signal, and a converter for converting output density. a reference lookup table storing data; a correction value calculation means for calculating a difference between a reserved value of a digital signal obtained from the A/D conversion means and a reference value of the reference lookup table as a correction value; and the correction value. Table conversion means sets a lookup table in which the contents of the reference lookup table are shifted entirely by the correction value calculated by the calculation means, and the density of the output of the A/D conversion means is determined using the lookup table. A color image reading device comprising a density correction means for performing adjustment. 2) An image sensor that reads a color image formed by an optical system as color data, an A/D converter that converts the output of the image sensor into a digital signal, and a lookup device that stores conversion data for output density conversion. a table; a correction value calculation means for calculating a difference between the average value of the digital signal obtained from the A/D conversion means and a reference value of the lookup table as a correction value; and a correction calculated by the correction value calculation means. addition means for adding the value and the value of the digital signal output from the A/D conversion means; and density correction means for sending the addition result of the addition means to the lookup table as data to be converted and adjusting the output density. A color image reading device comprising: