JPH06284433A - Film picture reader - Google Patents

Abstract

PURPOSE:To improve the picture quality of a reproduced picture by reducing black color distortion and coloring of the black color of the reproduced picture when a film picture is reproduced on a monitor television receiver or the like. CONSTITUTION:A peak hold circuit 12 detects signal levels RPK, GPK, BPK of a lowest luminance of a positive image of a film picture of a color negative film 3 based on R, G, B picture signals obtained by picking up the picture with a CCD 7. Furthermore, a NAM circuit 17 and a detection circuit 19 detect a maximum level VMAX among the signal levels RPK, GPK, BPK and an exposure control arithmetic operation circuit 20 generates an exposure control signal based on the maximum level VMAX Then drive of a light source 1 and an aperture 6 is controlled through drivers 8, 9 based on the exposure control signal so that a light receiving level at a low luminance edge of a dynamic range of the CCD 7 is equal to the signal levels RPK, GPK, BPK of the minimum luminance part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film image reading apparatus for reading an optical image of a film image photographed on each frame of a film through a photoelectric conversion member.

[0002]

2. Description of the Related Art FIG. 8 is a block diagram of a conventional film image reading apparatus. In the figure, an image (hereinafter referred to as a film image) of the color negative film 103 illuminated by the light source 101 via the diffusion plate 102 with a predetermined illuminance is
Color CCD (Charge Coupled Devic) with lens 104
e) An image is formed on the image pickup surface of 106, and the color CCD 106
Is photoelectrically converted by and read as an image signal. This image signal is separated from the color CCD 106 into image signals of respective colors of R, G, B, and double sampling (C
DS) circuit 107 and low-pass filter (LPF) 10
8 and the required noise is removed by the CDS circuit 107 and LPF 108, and then input to the negative / positive (N / P) inversion circuit 114.

Further, an image signal for a negative image (hereinafter referred to as a negative signal) is converted into an image signal for a positive image (hereinafter referred to as a positive signal) by an N / P inversion circuit 115,
After the white balance is adjusted by the WB amplifier 116, it is output to the image signal processing circuit in the subsequent stage (not shown). Then, after being subjected to γ correction and conversion into an NTSC signal by the image signal processing in the subsequent stage, the film image is output to the monitor TV for reproduction. Note that 117 and 118 are circuits that generate signals for white balance adjustment, and are division circuits that calculate the average value of the ratio of the image signals of B and R colors to the G image signal.

On the other hand, R, which is output from the LPF 108,
The matrix circuit 109 generates a predetermined luminance signal from the G and B image signals, and the detection circuit 110 smoothes the luminance signal to remove unnecessary portion luminance information such as a blanking period. A luminance signal including the luminance information of 1 is detected, and the detection signal is input to the exposure control arithmetic circuit 111. The exposure control calculation circuit 111 generates an exposure control signal from the input luminance signal, and based on the exposure control signal, the light emission amount of the light source 101, the aperture value of the aperture 105 and the CCD via the drivers 112, 113 and 114.
The drive of 106 is controlled to adjust the exposure level during imaging.

The adjustment of the exposure level will be briefly described with reference to FIG. FIG. 9 is a diagram showing film image reading characteristics of a conventional film image reading apparatus.

In the figure, the abscissa is the subject brightness, the ordinate is the output level of the negative signal in the CCD 106 to LPF 108, and f is an ideal CC having a dynamic range capable of covering the density characteristics of the color negative film 103.
The output level characteristic of the negative signal of each color of R, G, and B when a film image is captured using D is equivalent to the density characteristic of the color negative film 103.

The subject brightness does not directly represent the brightness of the film image (negative image) which is the object of the film image reading apparatus, but the brightness of the positive image obtained from the film image. Therefore, since the height relationship between the subject brightness and the actual brightness of the film image is reversed, the output level characteristic f decreases as the subject brightness increases.

In the conventional film image reading apparatus described above, the minimum output of the dynamic range W1 of the CCD 106 is taken into consideration in consideration of the fact that the ratio of the high brightness portion of the image captured on the color negative film 103 is usually large in the positive image. The level L is the density characteristic f of the color negative film 103.
The exposure level in the exposure control is adjusted so as to be in the vicinity of the saturation point Q on the high brightness side.

Further, in US Pat. No. 5,053,874, a lightness reference portion (usually an unexposed portion) is provided in a film image of a color negative film, and the film image is obtained by using a signal level of the lightness reference portion. A film image reader is shown which adjusts the black level of the positive signal.

[0010]

The former of the above-mentioned conventional film image reading devices is a CCD as shown in FIG.
Since the dynamic range W1 of 106 is narrower than the straight line portion (W2 + W3) of the density characteristic f of the color negative film 103, and the dynamic range W1 is adjusted to the high luminance side of the subject luminance, for example, it has the lowest luminance of the film image. When a portion (hereinafter referred to as the lowest luminance portion) is at the point P of the output level characteristic f, the low luminance area W between the point P and the point P'corresponding to the low luminance end of the readable area W2.
The output levels of 3 are all clipped to the maximum output level H of the CCD 106. Therefore, the reproduced image in the low-luminance region W3 is an image in which black is crushed.

FIG. 10 is a diagram showing the output characteristic of the conventional film image reading apparatus. In the figure, W2 'is a reproducible area of the film image, and W3' is a blackened area in which the reproduced image is blackened, which correspond to the readable area W2 and the low luminance area W3 of FIG. 9, respectively. The image in the low-brightness region W3 exceeds the dynamic range W1 of the CCD 106 and is all clipped and read at the maximum output level H. Therefore, even when the image is inverted to the image signal of the positive image, it is at the point P ′ in FIG. It is crushed to the corresponding black level and is not reproduced accurately.

Further, the conventional film image reading apparatus adjusts the white balance of the image signal of each color of R, G, B based on the signal level of the intermediate portion (gray portion) of the dynamic range W1 of the CCD 106, for example. However, since the density characteristics of the R, G, and B colors of the color negative film 103 do not generally match in the entire area of the subject brightness, the image signals of the R, G, and B colors converted to the image signal for the positive image are obtained. As shown in FIG. 10, the output levels match only at the point D corresponding to the reference point, and the output levels differ in other regions. Therefore, the range of the blackout region for the image signals of R, G, and B is different,
Coloring occurs in the reproduced image in the blackout area W3 ', and the quality of the reproduced image significantly deteriorates. For example, in the example of FIG. 10, the reproduction signal of the color R is included in the blackout region W3 ′,
A red coloring will occur in the portion to be reproduced black.

In order to avoid the above coloring problem, for example, the white balance of the read image signal is adjusted with reference to the output level of the lowest luminance portion (the output level corresponding to point P in FIG. 9). However, since the output level corresponding to the point P is clipped to the maximum output level H by the CCD 106 as described above and the black level is not accurate, it is difficult to reliably remove the above coloring phenomenon. is there.

FIG. 11 is a diagram showing the output characteristics of the conventional film image reading apparatus for film images having different average luminances.

In the conventional film image reading apparatus, the CCD
Since the dynamic range W1 of 106 is adjusted to the high luminance side of the film image, as shown in FIG. 11, the output characteristics of the film image with many bright portions are higher than those of the film image with few bright portions. The shape is shifted to the luminance side. Therefore, for example, the portion of the subject brightness E becomes a reproducible area in a film image having few bright portions, but becomes a blackout area in a film image having many bright portions, and blackout occurs in a low-luminance portion of the reproduced image. become. That is, if the average luminances of the film images are different, the reproduced image of the low luminance portion having the same luminance may or may not have blackout.

In the latter one of the above-mentioned conventional film image reading apparatuses, the density of the low-luminance portion in the film image is higher than that of the unexposed lightness reference portion, so that the low-luminance portion and the lightness reference portion are formed. Since the image information having the density between them disappears, the dynamic range of the image pickup system is narrowed. Also in this film image reading apparatus, it is difficult to eliminate the coloring in the blackout area W3 '.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a film image reading apparatus capable of appropriately reproducing a low-luminance portion of a film image and improving the quality of a reproduced image.

[0018]

SUMMARY OF THE INVENTION The present invention is a film image reading apparatus in which a light image of a film image photographed on a film is received by an image pickup means composed of a photoelectric conversion member and is read as an image signal. From the signal detecting means for detecting the image signal corresponding to the lowest luminance part in the positive image in the film image, and the level of the image signal detected by the signal detecting means is received at one end of the readable range of the image pickup means. An exposure level calculation means for calculating an exposure level matching the level and an exposure control means for controlling the exposure of the film image based on the calculation result of the exposure level calculation means are provided.

[0019]

According to the present invention, each time a film image of each frame is picked up, a film image is picked up in advance, and the image signal corresponding to the lowest luminance portion in the positive image in the film image is detected from the obtained image signal. To be done. Then, the exposure level is calculated so that the level of the detected image signal corresponding to the lowest luminance portion matches the light receiving level at one end of the readable range (dynamic range) of the image pickup means. Then, for example, the exposure in capturing the film image during reproduction is controlled based on the previously obtained calculation result.

[0020]

1 is a block diagram of a first embodiment of a film image reading apparatus according to the present invention. In the figure, 1 is a light source for illuminating the color negative film 3 and 2 is the light source 1
Diffusion plate for diffusing the light emitted from the device, 3 is a developed color negative film, 4 and 4'is a take-up roller pair for winding the color negative film 3, and 5 is an image taken on each frame of the color negative film 3. An optical system for forming an image (hereinafter referred to as a film image) on the image pickup surface of the image pickup device 7 described below, a diaphragm 6 for adjusting the amount of light incident on the image pickup device 7 described below,
Reference numerals 8 and 9 denote drivers for driving the light source 1 and the diaphragm 6, respectively.

In the image pickup device 7, photoelectric conversion elements (hereinafter referred to as pixels) such as photodiodes are arranged in a two-dimensional matrix, and R, R are provided on the light receiving surface of each pixel.
The G and B color filters are composed of an area sensor composed of a single-plate type color CCD (Charge Coupled Device) image sensor arranged in a checkered pattern. Image sensor 7
(Hereinafter, referred to as CCD 7) receives a film image formed on the image pickup surface for a preset time, and converts the received light energy into an electric signal (hereinafter referred to as an image signal) according to the amount of received light. Read. The image signal read by the CCD 7 separates the light receiving signal of each pixel into an image signal of each color of R, G, B, scans in the raster scanning direction, and is sequentially read by the processing circuit in the subsequent stage.

Reference numeral 10 is a correlated double sampling (CDS) circuit for reducing reset noise generated in the CCD 7, 11 is a low-pass filter (LPF) for reducing sampling noise, and 12 is an image signal (hereinafter referred to as a negative image) for a negative image. , Negative signal) is inverted to an image signal for a positive image (hereinafter referred to as “Positive signal”) Negative / Positive (N /
P) An inverting circuit.

Reference numeral 13 denotes an offset correction circuit for adjusting a black level by applying a predetermined offset to the image signal after N / P inversion, and 14 performs a predetermined signal processing on the image signal of each color of R, G and B. A signal processing circuit for generating an NTSC signal composed of a luminance (Y) signal and a chroma (C) signal, 15
Is a monitor TV for reproducing and displaying a film image read by the film image reading apparatus.

The CDS circuit 10, LPF 11, N /
The P inversion circuit 12 and the offset correction circuit 13 include R, G,
Each of the three circuits having the same function corresponding to each color image signal of B is provided. In the following description, for convenience,
The image signals of each color of R, G, and B for the negative image are R _N ,
G _N, expressed in B _N, R for positive image, G, image signals of respective colors of B is set to be represented by _{R P, G P, B P} .

Further, the signal processing circuit 14 has a WB circuit 141 for adjusting white balance and γ for gradation correction.
Image signals R _p , G _p , and B of the respective colors of the circuit 142, R, G, and B
Y and color difference signals from _{p (R P -Y), (} B P -Y) matrix circuit 143 generates a and the Y signal and color difference signals (R _P -Y), from the (B _P -Y) above It has a Y / C signal generation circuit 144 that generates a Y signal and a C signal.

Reference numeral 16 denotes R, G, and
A peak hold circuit that holds the peak levels of the image signals R _N , G _N , and B _N of each color of B and outputs them as peak level signals R _PK , G _PK , and B _PK , and 17 is the peak level signals R _PK and G _PK . _PK, detects the maximum level of B _PK, the maximum level signal _{V NAM (= MAX {R PK} , G PK, B PK})
Non-additive mixing (NAM (Non Addit
ive Mixing)) circuit, 18 is an offset calculation circuit for calculating an offset value for the offset correction circuit 13.

The film image of each frame of the color negative film 3 is output from the CCD 7 because the darkest portion (hereinafter referred to as a black portion) in the reproduced image has the lightest density and the highest light transmittance. Of the image signals, the level of the image signal corresponding to the black portion becomes maximum. Therefore, the peak hold circuit 16 is connected to the CCD 7
The black portion of the film image is detected by detecting the peak level of the image signal of each color of R, G, and B read in (1).

By the way, since the gradation characteristics of each color of R, G, B in the color negative film 3 are usually different, the black portion of the film image corresponding to the peak level detected for each color of R, G, B is It does not match. R,
From the detected peak level for each of G and B, it is necessary to further specify the black portion in the film image to be the reference. In this embodiment, the black portion of the film image corresponding to the maximum peak level of the peak levels of the R, G, and B colors is used as a reference, and the NAM circuit 17 uses the reference black portion (hereinafter referred to as reference). The black part) is detected.

The offset calculation circuit 18 includes R, G,
Three arithmetic circuits 181, corresponding to the image signals of the respective colors B,
182 and 183, and subtracts the maximum level detected by the NAM circuit 17 from the peak level of the image signal of each color of R, G, B respectively, and the image signal of each color of R, G, B R _N , G Offset level R _OS (= R _PK for _N and B _N
−V _MAX ), G _OS (= G _PK −V _MAX ), B _OS (= B _PK −V
_MAX ) is calculated. Then, these offset levels R _OS , G _OS , and B _OS are converted into offset levels R _OSP , G _OSP , and B _OSP for the positive signal, and the offset correction circuit 1
It outputs to the correction circuits 131, 132, 133 provided corresponding to the image signals R _P , G _P , B _P of each color of R, G, B in 3 respectively.

Reference numeral 19 removes unnecessary signal components such as the blanking period from the maximum level signal V _NAM output from the NAM circuit 17 and detects the maximum level signal V _NAX ′ in the image signal for the true film image. The detection circuit, 20 is
From the detected maximum level signal V _{N AM} ′ to the maximum level V _MAX
And an exposure control calculation circuit for calculating a predetermined exposure control value related to the light emission amount of the light source 1 and the aperture amount of the diaphragm 6 based on the maximum level V _MAX . Exposure control arithmetic circuit 20
Is, for example, the maximum level V _MAX a pre set, for example, the maximum output and the reference level V _ref slightly lower than the level using information level difference obtained by comparing the maximum level V _MAX is the reference of the CCD7 Exposure is performed so as to match the level V _ref , that is, the output level of the CCD 7 with respect to the transmitted light of the reference black portion of the film image (hereinafter referred to as the reference black portion level) matches the maximum output level of the dynamic range of the CCD 7. Calculate the control value.

The exposure control value is calculated as a correction coefficient value for the current light emission amount of the light source 1 and the current aperture amount of the diaphragm 6, and the calculation results are output to the drivers 8 and 9, respectively. The drivers 8 and 9 multiply the current control value by the input correction coefficient value to generate a new control value, and change the light emission amount of the light source 1 and the aperture amount of the diaphragm 6 based on this new control value. For example, when the maximum level V _MAX , that is, the reference black part level V _MAX is lower than the reference level V _ref ,
Change the aperture of the diaphragm 6 to a value larger than the current aperture,
The amount of light incident on the CCD 7 is increased so that the reference black portion level V _MAX matches the reference level V _ref . If the reference black portion level V _MAX does not reach the reference level V _ref even if the diaphragm 6 is opened, the light emission amount of the light source 1 is changed to a value larger than the current light emission amount, and the incident light amount to the CCD 7 is further increased.

In the above structure, a film image is picked up at a predetermined cycle like a moving image, and each image signal is predetermined by the CDS circuit 10, LPF 11, N / P inversion circuit 12, offset correction circuit 13 and signal processing circuit 14. After the image signal processing is performed, the image is reproduced on the monitor TV 15.

In the first image pickup, a preset control value is output from the exposure control calculation circuit 20 to the driver 8 of the light source 1 and the driver 9 of the diaphragm 6, and preset exposure control (hereinafter referred to as initial exposure control). ) Is done. That is, the frame of the color negative film 3 set to be imaged is illuminated with light emitted from the light source 1 with a predetermined light amount (illuminated with a predetermined illuminance), and a film image having a predetermined brightness is formed on the frame surface. To be done. The optical image of the film image is formed on the image pickup surface of the CCD 7 by the optical system 6. Then, the CCD 7 receives the optical image formed on the imaging surface for a predetermined time and reads the film image. The amount of light transmitted to the CCD 7 is limited to a preset amount of light by the diaphragm 6, and in the first imaging, initial exposure control determined by the amount of transmitted light and the light receiving time (shutter speed) of the CCD 7 is performed. .

The image signals read by the CCD 7 by the above exposure control are the image signals R _N , G _N , R, G, B of the respective colors of R, G, B.
It is separated into B _N and read by the CDS circuit 10,
After the noise caused by the read / read operation of the image signal of the CCD 7 is removed by the S circuit 10 and the LPF 11 in the subsequent stage, it is inverted by the N / P inversion circuit 12 into positive signals R _P , G _P , and B _P. These R, G, B image signals R _P ,
Offset correction circuit 13 performs low level (black level) correction on G _P and B _P , respectively.

The black level correction is performed by the image signal R _P ,
This is performed by applying offsets of the offset levels R _OSP , G _OSP , and B _OSP input from the offset calculation circuit 18 to the low levels of G _P and B _P. As a result, the black levels of the image signals R _P , G _P , and B _P are corrected to the signal level corresponding to the reference black portion in the film image. Then, after black level correction, the signal processing circuit 14 performs predetermined signal processing such as WB balance and γ correction and generation of Y and C signals, and monitors the Y and C signals.
15 and the film image is reproduced on the monitor TV 15.

On the other hand, the image signals R _N , G _N and B _N output from the LPF 11 are input to the peak hold circuit 16 and the offset calculation circuit 18. The peak hold circuit 16 holds the peak level of each of the input image signals R _N , G _N , and B _N to generate peak level signals R _PK , G _PK , and B _PK , and these peak level signals R _{The PK} , G _PK , and B _PK are input to the NAM circuit 17. The NAM circuit generates a maximum level signal V _NAM from the input peak level signals R _PK , G _PK and B _PK and inputs it to the detection circuit 19. Detection circuit 19 detects a maximum level signal V _NAM 'in the input of the maximum level signal V _{NA M} to remove unwanted detection signal in smooth to blanking period or the like has an image signal corresponding to only the film image Then, the detected signal V _NAM ′ is input to the exposure control arithmetic circuit 20.

Then, the exposure control calculation circuit 20 detects the reference black portion level V _MAX from the maximum level signal V _NAM ′, and calculates a predetermined exposure control value based on the reference black portion level V _MAX . The exposure control value is fed back to the drivers 8 and 9, and the exposure control based on the exposure control value is performed in the second imaging.
Hereinafter, a predetermined exposure control value based on the brightness of the reference black portion of the film image is sequentially calculated from the image signal captured last time, and the exposure in the current imaging is controlled by the exposure control value.

The maximum level signal V _NAM generated by the NAM circuit 17 is input to the offset calculation circuit 18. The offset calculation circuit 18 uses the maximum level signal V
The offset levels R _OSP , G _OSP , and B _OSP are generated from the _NAM and the peak level signals R _PK , G _PK , and B _PK input from the peak hold circuit 16 and input to the offset correction circuit 13.

In the above embodiment, the proper exposure control value is fed back to the drivers 8 and 9 of the light source 1 and the diaphragm 6 when reproducing each film image.
Film images of all frames of the color negative film 3 are picked up in advance to calculate exposure control values for each film image, and when reproducing each film image, the light emission amount of the light source 1 and the aperture 6 of the aperture 6 are adjusted by the exposure control values. The exposure amount may be controlled by setting the opening amount.

FIG. 2 is a diagram showing the film image reading characteristics of the film image reading apparatus.

In the figure, the horizontal axis represents subject brightness, the vertical axis represents the output level of the negative signal output from the CCD 7 or LPF 11, and f represents an ideal CCD having a dynamic range capable of covering the density characteristics of the color negative film 3.
It is an output level characteristic of a negative signal of each color of R, G, and B when a film image is picked up using. The output characteristic indicated by the dotted line is the characteristic of the R image signal, the output characteristic indicated by the solid line is the characteristic of the G image signal, and the output characteristic indicated by the alternate long and short dash line is the characteristic of the B image signal.

The subject brightness does not directly represent the brightness of the film image (negative image) which is the object of the film image reading apparatus, but the brightness of the positive image obtained from the film image. Therefore, since the height relationship between the subject brightness and the actual brightness of the film image is reversed, the output level characteristic f decreases as the subject brightness increases. W1 is the CCD 7
Is an actual dynamic range, and W2 is a readable area of the subject brightness corresponding to the dynamic range W1.

As is clear from the figure, since the actual dynamic range W1 is narrower than the ideal CCD dynamic range, it is lower than, for example, the readable area W2 in the image signal obtained by reading the film image. The image signal of the luminance portion is clipped at the maximum output level H of the dynamic range.

In the film image reading apparatus according to the present invention,
When capturing a film image as described above, the light emission amount and aperture of the light source 1 are adjusted so that the output level V _{MAX of the} CCD 7 that receives the transmitted light of the reference black portion in the film image becomes the maximum output level H of the dynamic range. Exposure control is performed by adjusting the opening amount of No. 6.

That is, in FIG. 2, assuming that point P is the reference black portion level in the film image, the maximum output level H of the dynamic range of the CCD 7 is the reference black portion level P.
The exposure control is performed so as to match with. Since the reference black area level P has the lowest brightness in the film image,
With the above exposure control, a signal having an output level corresponding to the luminance is surely read on the low luminance side, and the output level of the low luminance portion is not clipped by the dynamic range W1 of the CCD 7. As described above, a blackout region (a region corresponding to W3 in FIG. 9) does not occur in the low-luminance portion in the film image.

FIG. 3 is a diagram showing the output characteristics of the film image reading apparatus. In the figure, the horizontal axis represents the subject brightness, the vertical axis represents the output level of the positive signal, which is the output level output from any one of the N / P inversion circuits 12 to γ circuit 142. W2 ′ is a reproducible area corresponding to the readable area W2 in FIG. 2. The output characteristic indicated by the dotted line is the characteristic of the R image signal, the output characteristic indicated by the solid line is the characteristic of the G image signal, and the dashed line is the dashed line. The output characteristic shown is the characteristic of the B image signal.

As described above, since the maximum output level H of the dynamic range W1 of the CCD 7 is made to coincide with the reference black portion level P, the luminance at the low luminance end of the reproducible area is the subject luminance corresponding to the reference black portion level P. Corresponding to.
Therefore, in the output characteristics of the positive signal, a black crushed area does not occur on the low luminance side of the reproducible area, so that the low luminance portion of the film image is suitably reproduced on the monitor TV 15 without causing the black crushed, and the image quality deteriorates. Is reduced.

In adjusting the black level of the positive signal, the black level of the image signals R _P , G _P , and B _P of each color of R, G, and B is based on the signal level V _MAX corresponding to the point P of the reference black portion. Since the output level of each color is substantially the same at the low luminance end of the reproducible area W2 ', the chromatic color is not colored in the image of the low luminance portion to be reproduced in black.

FIG. 4 is a diagram showing output characteristics of the present film image reading apparatus for film images having different average luminances. This drawing depicts an example of the output characteristics of a positive signal obtained by capturing two types of film images having different average luminance at the coordinates shown in FIG.

In the figure, is the characteristic of a film image in which the photographed subject has many bright parts and the average brightness of the entire screen is high. Is a characteristic for low film images. In both characteristics, the dotted line is the characteristic of the R image signal, the solid line is the characteristic of the G image signal, and the alternate long and short dash line is the characteristic of the B image signal.

Based on the average brightness of the film image, for example, the dynamic range W1 of the CCD 7 is controlled so that the dynamic range W1 is in the region from the intermediate region to the high brightness (see FIG. 2) with respect to the subject brightness (see FIG. 2). In a high-definition film image, the image signal of the low luminance portion where the output level of the CCD 7 is equal to or higher than the maximum output level H of the dynamic range W1 is clipped at the maximum output level H, and the black color of the reproduced image of the low luminance portion is crushed Will end up.

In the film image reading apparatus, the reference black portion level V _MAX obtained by picking up each film image is CCD.
Since the exposure control is performed so as to match the maximum output level H of the dynamic range W1 of 7, the minimum output level of the film image with high average brightness and the minimum output level of the film image with low average brightness are shown in FIG. And the minimum output level corresponds to the lowest luminance part of each film image, the black of the reproduced image of the low luminance part is not destroyed.

Further, as described above, the reference black level V
Image signals R _P , G _P , and B _P of R, G, and B colors based on _XAM
Since the black level is corrected, the subject brightness at which the image signals R _P , G _P , and B _{P of} the R, G, and B colors have the minimum levels substantially match, and coloring occurs in the reproduced image in the low-luminance portion. Nor. Therefore, even when the average brightness of the film images is different, it is possible to preferably reproduce the black portion of each reproduced image.

FIG. 5 is a block diagram of a second embodiment of the film image reading apparatus according to the present invention. In the first embodiment, the film image is captured by the area sensor, but in the second embodiment, the film image is captured by the line sensor.

In the figure, members having the same functions as those shown in FIG. 1 are designated by the same reference numerals. Also, 30
Is an image pickup device including a color CCD line sensor in which three CCD line sensors are arranged in the sub-scanning direction (see FIG. 6) and each CCD line sensor is provided with a spectral filter of R, G, B ( Hereinafter referred to as line sensor).

As shown in FIG. 6, the line sensor 30 scans the film image F formed on the image pickup surface from one end A to the other end A'to read the film image F.
That is, the line sensor 30 scans the image signals R _N , G _N , and B _N of the respective colors of R, G, and B while scanning in the sub-scanning direction in synchronization with the scanning speed in the main scanning direction (see FIG. The data is sequentially read in the S direction) and input to the CDS circuit 10.

Reference numeral 31 is a clamp circuit for adjusting the levels of the image signals R _N , G _N , and B _N to a predetermined reference level (light reception level when light is not incident), and 32 is an analog signal converted into a digital signal. It is an A / D converter. The clamp circuit 31 and the A / D converter 32 are provided.
Has three circuits each having the same structure corresponding to each of the R, G, and B color image signals.

Numeral 33 denotes R in the line sensor 30,
This is a delay circuit that corrects the deviation of the reading timing of the image signals of R, G, and B colors due to the arrangement position of the CCD line sensor of each of G and B colors. Delay circuit 33
Is a line delay circuit 331, 332 for delaying the phase of each of the R and B color image signals by a predetermined amount.
have.

For example, R, which constitutes the line sensor 30,
When the CCD line sensors for the respective colors G and B are arranged in the order R, B, G in the sub-scanning direction (see FIG. 6), the line delay circuit 331 includes the CCD line sensor 2 in the sub-scanning direction. The line delay circuit 332 delays the phase of the R color image signal R _N by the amount of movement by the line, and the line delay circuit 332 causes the CCD line sensor to move by the amount of one CCD line sensor in the sub-scanning direction. Delay the phase of B _N. As a result, the read timings of the R and B color image signals are corrected so as to match the read timing of the G color image signal, and the R, G, and B color images obtained by reading the image of the same line of the film image are read. The signals R _N , G _N , B _N are corrected to form a set of image signals to be processed.

Reference numeral 34 is a circuit block corresponding to the peak hold circuit 16 and the NAM circuit 17 in FIG. 1, which is a reference black portion detection circuit for detecting the reference black portion in the film image. The reference black part detection circuit 34 includes a delay circuit 341,
It is composed of a first averaging circuit 342, a latch circuit 343, a second averaging circuit 344, a comparison circuit 345, a latch circuit 346, and a NAM circuit 347. The delay circuit 341, the first and second averaging circuits 342,
344 and the latch circuits 343 and 346 are R,
3 circuits having the same structure corresponding to the image signals of G and B colors are used.
It has one by one.

The delay circuit 341, the first averaging circuit 342, and the latch circuit 343 in the reference black part detection circuit 34 are described.
The second averaging circuit 344 reduces the erroneous detection at the time of extracting the image signal corresponding to the reference black portion from the image signal read by each pixel forming the line sensor 30, so that 4 (= 2 × 2) ) The image signal is handled on a pixel-by-pixel basis, and four image signals of (2 × 2) pixels are extracted and an average value of these image signals is calculated.

That is, as shown in FIG. 7 (a), the film image is an image signal K (i, j; i = 1, 2, ..., N, j =) read by each pixel of the CCD line sensor.
1, 2, ..., M) arranged in a two-dimensional matrix of (n × m), image signals K (i, j), K (i +) are obtained as shown in FIG. 1, j), K (i, j + 1), K (i + 1, j + 1) average value K _AVE (I, J; I = 1, 2, ..., N / 2, J =
1, 2, ..., M / 2) are extracted.

Here, the operation of each of the delay circuit 341, the first averaging circuit 342, the latch circuit 343 and the second averaging circuit 344 will be briefly described by taking the G image signal G _N as an example. The phase of the G image signal G (1,1) output from the A / D converter 32 is delayed by one line in the sub-scanning direction by the delay circuit 341, and
Image signal G (2,2 of the next line output from the converter
1) and the average value G _AVE1 (1, of the image signal G (1,1) and the image signal G (2,1).
1) = (G (1,1) + G (2,1)) / 2 is calculated.

The average value G _AVE1 (1,1) is the latch circuit 3
The next average value G _{AV E1} (1,2) = (G (1,2)
It is input to the second averaging circuit 344 together with + G (2,2)) / 2. Then, in the second averaging circuit 344, the average value of the average value G _AVE1 (1,1) and the average value G _{AV E1} (1,2), that is, a region composed of four pixels (hereinafter, unit region) Mean) G _AVE (1,1) = (G _AVE1 (1,1) + G _AVE1 (1,
2)) / 2) is calculated. Hereinafter, in a similar manner, the average value G _AVE (I, J; I = 1, 2, ..., N of each unit area for image signals G (1,1) to G (n, m) of n rows and m columns / 2, J =
1, 2, ..., M / 2) are calculated.

The latch circuit 346G for the G image signal in the comparison circuit 345 and the latch circuit 346 detects the peak level G _PK of the G color image signal G _N. The comparison circuit 345 receives the average value G _AVE (p, q) latched by the latch circuit 346G and the average value G input from the second averaging circuit 344G for the G image signal.
Compare with _AVE (I, J), and if G _AVE (I, J)> G _AVE (p, q),
A latch signal is output to the latch circuit 346G to change the content of the latch circuit 346G to the average value G _AVE (I, J).

That is, the average values G _AVE (1,1), G _AVE (1,2), which are sequentially output from the second averaging circuit 344G,
..., G _AVE (I, J) is compared with the peak value of the previously output average value G _AVE , and every time the peak value is exceeded, the content of the latch circuit 346G is updated to the average value G _AVE. , The maximum average value G _MAX (I, J) corresponding to the peak level G _PK of the image signal G _N is detected.

The latch signal output from the comparison circuit 345 is also input to the latch circuits 346R and 346B for the R and B image signals R _N and B _N in the latch circuit 346, and the R and B image signals are input. For R _N and B _N , the average value of the region of 4 pixel units corresponding to the same position as the position detected as the black portion in the film image by the G image signal G _N is the maximum average value R _MAX (I, J ), B _MAX (I, J).

The maximum average values G _MAX (I, J) and R _MAX (I,
J) and B _MAX (I, J) are input to the NAM circuit 347, and the N
The AM circuit 347 allows the maximum level V _MAX ′ of these to be reached.
(= MAX {G _MAX (I, J), R _MAX (I, J), B _MAX (I, J)})
Is detected. The maximum level V _MAX ′ corresponds to the maximum level V _MAX described in the first embodiment, and the black portion of the film image corresponding to the maximum level V _MAX ′ becomes the reference black portion. Then, the maximum level V _MAX ′ is input to the exposure control calculation circuit 20, and the correction coefficient values of the light emission amount of the light source 1 and the aperture amount of the diaphragm 6 are calculated as in the first embodiment.

The above-mentioned correction coefficient value is obtained by the D / A converter 3
5, 36 are respectively converted into analog signals and fed back to the drivers 8, 9 and, in the next image pickup operation, the CCD 3 for the transmitted light of the reference black portion of the film image.
The exposure control is corrected so that the output level of 0 becomes the maximum output level of the dynamic range of the CCD 30.

Reference numeral 37 denotes an offset calculation circuit of the offset correction circuit 13, which corresponds to the offset calculation circuit 18 of FIG. The offset calculation circuit 37 includes R, G,
Level difference detection circuits 38, 3 for the B color image signals
9 and 40 and multiplication circuits 41, 42 and 43.
The level difference detection circuits 38, 39 and 40 detect the maximum level V _MAX ′ detected by the NAM circuit 347 and the peak levels G _MAX (I, J) and R _MAX (I of the image signals of R, G and B colors. ,
J), B _MAX (I, J) level difference ΔR (= V _MAX ′ −R
_MAX (I, J)), ΔG (= V _MAX ′ −G _MAX (I, J)), ΔR
(= V _MAX ′ −B _MAX (I, J)) is detected. In addition, the multiplication circuits 41, 42, and 43 have the level difference ΔR,
Offset values R _OS , G _OS , are obtained by multiplying ΔG, ΔB by a correction coefficient value for exposure control calculated by the exposure control calculation circuit 20.
Calculate B _OS .

The offset values R _OS , G _OS , and B _OS are input to the offset correction circuit 13, and the white levels of the image signals R _N , G _N , and B _N obtained by the next image pickup are the offset values. R _{O S,} G _OS, is corrected by B _OS. The image signals R _N , G _N , and B _N after white level correction are the N / P inversion circuit 1
R _P to the positive signal by 2, G _P, after being converted to B _P, is input to the signal processing circuit 14, is performed process of generating a predetermined signal processing and the Y signal and the C signal described above monitors TV1
5 is output.

As described above, since the white level of each image signal R _N , G _N , B _N is corrected to the level corresponding to the reference black portion at the stage of the negative signal before N / P inversion, N / P The black levels of the R, G, and B image signals R _P , G _P , and B _P after inversion are adjusted to the black levels corresponding to the reference black portions in the film image. Therefore, as described with reference to FIGS. 3 and 4, the monitor TV 15 is appropriately reproduced without coloring the low-luminance portion in the film image.

When the image signal is read for the first exposure calculation, the maximum level V _MAX is set to the line sensor 30.
When it is equal to or exceeds the maximum value of the dynamic range of, as a reading error, the reference setting values of the light source 1 and the aperture 6 are changed, and the reading operation of the image signal for the exposure calculation is performed again.

Although the signal processing circuit 14 is provided in the film image reading apparatus in the above-described embodiment, the signal processing circuit 14 is used.
R, G, B image signals R _P , G _P , B _P
May be directly output.

Although the case of reading a film image of a color negative film has been described, the same exposure control may be performed when a film image of a monochrome negative film or a reversal film is read.

[0076]

As described above, according to the present invention,
In a film image reading device that receives an optical image of a film image shot on a film by an image pickup unit composed of a photoelectric conversion member and reads it as an image signal, from a previously picked-up image signal to the lowest luminance portion in the positive image in the film image. The corresponding image signal is detected, and the exposure level at the time of exposure is adjusted so that the level of the image signal matches the light receiving level at one end of the readable range (dynamic range) of the image pickup means. The low-luminance portion of the film image is properly captured regardless of the luminance distribution of the image. As a result, the reproduced image in the low-luminance portion is not blackened and the image quality is not deteriorated.

Further, by adjusting the black level of the reproduced image to the black level corresponding to the lowest luminance portion in the film image, even when the average luminance of the film image is different, the low luminance portion can be properly reproduced. In addition, it is possible to prevent unnecessary coloring from occurring in the reproduced image of the low luminance portion.

[Brief description of drawings]

FIG. 1 is a block diagram of a first embodiment of a film image reading apparatus according to the present invention.

FIG. 2 is a diagram showing film image reading characteristics of the film image reading apparatus according to the present invention.

FIG. 3 is a diagram showing output characteristics of the film image reading apparatus according to the present invention.

FIG. 4 is a diagram showing output characteristics of the film image reading apparatus according to the present invention for film images having different average luminances.

FIG. 5 is a block diagram of a second embodiment of the film image reading apparatus according to the present invention.

FIG. 6 is a diagram showing a reading and scanning direction of a CCD line sensor for a film image.

7A and 7B are diagrams showing an image signal obtained by reading a film image, FIG. 7A is a diagram showing a state in which image signals of respective pixels are arranged in a two-dimensional matrix, and FIG. 7B is a diagram showing (2 × 2) pixels. It is a figure which shows the state which extracted the average value of the image signal of each image in the unit, and has arranged it in the two-dimensional matrix form.

FIG. 8 is a block diagram of a conventional film image reading device.

FIG. 9 is a diagram showing film image reading characteristics of a conventional film image reading apparatus.

FIG. 10 is a diagram showing output characteristics of a conventional film image reading apparatus.

FIG. 11 is a diagram showing output characteristics of a conventional film image reading apparatus for film images having different average luminances.

[Explanation of symbols]

 1 Light Source 2 Diffusion Plate 3 Color Negative Film 4, 4'Winding Roller Pair 5 Optical System 6 Aperture 7 Imaging Device (CCD) 8, 9 Driver 10 CDS Circuit 11 Low Pass Filter 12 N / P Inversion Circuit 13 Offset Correction Circuit 14 Signal Processing Circuit 141 WB circuit 142 γ circuit 143 Matrix circuit 144 Y / C signal generation circuit 15 Monitor TV 16 Peak hold circuit 17 NAM circuit 18 Offset calculation circuit 19 Detection circuit 20 Exposure control calculation circuit 30 Line sensor 31 Clamp circuit 32 A / D converter 33,341 Delay circuit 34 Reference black part detection circuit 342,344 Averaging circuit 343,346 Latch circuit 345 Comparison circuit 347 NAM circuit 35,36 D / A converter 37 Offset calculation circuit 38,39,40 Level difference detection Circuit 41, 42, 43, multiplication circuit M motor

Claims (1)

[Claims] 1. A positive image in a film image in a film image reading device which receives an optical image of a film image photographed on a film by an image pickup means composed of a photoelectric conversion member and reads it as an image signal. Signal detecting means for detecting an image signal corresponding to the lowest luminance portion, and an exposure level at which the level of the image signal detected by the signal detecting means matches the light receiving level at one end of the readable range of the image pickup means. Exposure level calculation means for
A film image reading apparatus comprising: an exposure control unit that controls the exposure of the film image based on the calculation result of the exposure level calculation unit.