JPH0326807B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a screen position detection method and apparatus for detecting the position of an exposure screen of a film such as a photograph.

Conventionally, in film processing laboratories, etc., in order to automate the printing process, etc., the center position of the exposure screen of negative film is detected, and a notch (as shown in Fig. 1) is cut out at the side edge of the film base corresponding to the center position. It was usual to provide a notch (hereinafter referred to as a notch).
However, density unevenness B often occurs on the film base due to blurring, fogging, etc. of light from the exposure screen A.

In conventional screen position detection methods and devices, in order to detect such density unevenness on the film base not as exposed screen A but as base density area C, a certain tolerance range is set for the density value detected as the base density value. (This is called tolerance). In other words, if the reference value is the value measured by the screen detector of a normal base density with no density unevenness such as bleeding or fogging, then in the screen detection logical operation that calculates the center position of the screen from the measured value of this screen detector, If the density value of the negative film captured by the screen detector was greater than the reference value plus the tolerance, it was recognized as an image, otherwise it was recognized as the base density.

However, in such a conventional screen position detection method, as shown in FIG. 1, density unevenness such as bleeding exists on the right side of the screen, and this density unevenness is caused by overexposure. If there is a large density unevenness like this, it will be detected as a blurred exposed screen, and the calculation of the center position of the screen will be incorrect, and the notch 1 will be struck at position O', which is not the true center position O of the screen. It had the drawback of sagging. This also applies when there is blurring on the left side of the drawing, as shown in Figure 2, for example, where the notch 1 is placed not at the true center position O of the screen but at the erroneous position O''. Put it away.

If a notch is struck in the wrong position in this way, color laboratory systems that rely on notch information, especially in the automatic printing process, will suffer from loss due to the edges of the print being cut off, which will affect the overall system. The drawback was that it reduced efficiency.

The present invention was invented in view of the above points, and provides a tolerance for film base density unevenness, etc., by moving relative to a film such as a photograph.
A film surface density detection means for detecting the density of the film surface based on VBTL and VBTH, which is a tolerance for blurring appearing at both ends of an overexposed screen; Said above
A first movement amount count that starts counting the relative movement amount between the film surface density detection means and the film from the time when it is detected that the film surface density has become larger than the sum of VBTL, and stops counting after a predetermined period of time has elapsed. and the first movement amount counting means, and then the film surface density detecting means detects that the density of the film surface becomes greater than the sum of the base density of the film and the VBTH within the predetermined time. If this is detected, the count is reset and counting is started again, and within the predetermined time, the film surface density detection means detects that the film surface density is greater than the sum of the film base density and the VBTH. If it is not detected, the second count continues counting.
An apparatus characterized in that it is equipped with a movement amount counting means and a calculation means for calculating the center position of the screen based on the count value by the second counting means, the object of which is to An object of the present invention is to provide a screen position detection device capable of determining the true center position of a screen even if there is large density unevenness such as bleeding at the side edge of the screen.

The present invention will be explained in detail below based on FIGS. 3 to 5.

FIG. 3 is a block diagram showing an example of the configuration of a screen position detection device according to the present invention. In Figure 3,
Reference numeral 31 denotes a light source for irradiating the negative film 33 to measure the film density.
3 is irradiated. The light transmitted through the negative film 33 is detected by a light receiving element 34, amplified by a screen density detection circuit 35, converted into a digital signal, and then input to a screen detection logical operation circuit 37. The light source 31, slit 32, light receiving element 34, and screen density detection circuit 35 as a whole constitute the screen density detector 3.
6. Further, the negative film 33 is driven by a pulse signal 38 and moved between the slit 32 and the light receiving element 34 one pulse at a time. Meanwhile, the pulse signal 38 is counted by two counters 39 and 40, and the counted value is input to the screen detection logic operation circuit 37. The screen detection logical operation circuit 37
Now, the screen density detection circuit 35, count 3
It takes in the screen data from 9 and 40, performs a logical operation to detect the position of the screen, calculates the notch driving position on the screen, and outputs a notch driving signal to the notch driving blade drive circuit 41. The notch driving blade drive circuit 41 is connected to the screen detection logic operation circuit 37.
The notch driving blade 42 is driven in accordance with the notch driving signal from. The notch driving blade 42 is driven by a drive signal from the notch driving blade driving circuit 41, and drives a notch into an appropriate position on the side edge of the negative film 33.

Although the configuration example of the present invention has been described above, the principle of the present invention will be explained in more detail next.

In this invention, two levels of tolerance are provided when detecting the screen of a negative film. In other words, the tolerance for normal film base density unevenness, normal bleeding, etc.
There are two levels of tolerance: VBTL (VBTL) and tolerance for relatively large blurring especially seen at both ends of an overexposed screen (VBTH).

First, detection of the right side of the exposure screen will be described.
Since the negative film 33 is driven in the direction of the arrow shown in FIG. 3 (from left to right), the surface of the negative film is scanned by the slit light in the direction of the arrow shown in FIG. If the density on the film base surface becomes greater than the value obtained by adding the tolerance VBTL to the reference value, which is the normal base density (this density is defined as D _L ), at the position shown in Figure 4a, then at this position, the screen A distance monitoring counter 39 that recognizes the right side and stops counting at a certain distance (for example, 2 mm) from this position is set and starts counting, and at the same time, an exposure section accumulation counter 40 also starts counting. i.e. two tolerances
Certification of exposed and unexposed areas will begin while establishing VBTL and VBTH. This recognition is repeated while driving the film one pulse at a time using the film drive pulse 38. During this time, the exposure section accumulation counter 40 counts and accumulates the count number in the portion recognized as the exposure section. Now, before the counter 39 finishes counting, that is, within a certain driving distance of the film from the position shown in _FIG . Assume that it has grown. At this time, the slit light is at the position shown in FIG. 4b. In this case, this position on the film is replaced as the true right side of the exposure screen, the accumulation counter 40 is corrected, and the distance counter 39 is reset. This means that from the position where the right side is detected with the tolerance VBTL (the position where the film density is darker than D _L ; the position in Figure 4 a), the position where the exposed area is detected with the tolerance VBTH (the position where the film density is darker than D _H Darker position; position in Figure 4b)
This is because there is an extremely high probability that it is a blur. When the right side of the exposure screen is replaced in this way, the subsequent screen detection process involves providing two tolerances, VBTL and VBTH, and identifying the exposed and unexposed areas of the film for each drive pulse. If there is an exposed portion, it is accumulated in the accumulation counter 40. The reason why the screen is recognized by providing two tolerances is that if the right side of the exposed screen has blur, there is a high probability that the left side to be detected next will also have blur.

Next, if the film density has not become darker than D _H and the detected position on the right side of the exposure screen has not been replaced by the time the distance counter 39 finishes counting, the accumulation counter 40 continues counting without making any corrections. At the same time, in subsequent detection, exposed areas and unexposed areas are identified using only the tolerance VBTL, and if there is an exposed area, it is stored in the accumulation counter 40. The reason for certifying screens only with tolerance VBTL is that if there is no blurring on the right side of the exposed screen, there is an extremely high probability that it is a properly exposed screen or an underexposed screen, and in particular, it is necessary to accurately detect underexposed screens. Tolerance
This is because it is more advantageous to detect the screen using only VBTL.

Next, detection of the left side of the exposure screen will be explained.

First, if the detected position on the right side is not corrected or replaced, the exposed and unexposed areas are recognized using only the tolerance VBTL, and when the unexposed area is detected, that position is exposed. The count number accumulated in the accumulation counter 40 is read out to the logic operation circuit 37, and the screen size detected in the logic operation circuit 37 is determined to be within the allowable size for one screen. Perform size test. If the detected screen size is within the allowable size, the notch insertion position is calculated using the screen size as one screen, and is registered in a buffer for notch insertion position storage in the logic operation circuit 37. When driving a notch, the notch position is read from the buffer, and the notch driving circuit 41 drives the notch driving blade 42 to drive the notch into an appropriate position on the negative film 33. If the detected screen is not within the allowable size, the screen is registered in the exposure block buffer in the logical operation circuit 37 as an abnormal exposure block.

Next, when the detection position on the right side is corrected and replaced, two tolerances VBTL and VBTH are set to identify exposed and unexposed areas, and the left side of the screen is detected. . When the density of the negative film becomes thinner than D _H and an unexposed area is detected (position b' in FIG. 5), the counting of the accumulation counter 40 is stopped, and the count value of the counter 40 is read out to the logic operation circuit 37. The screen size is verified, and if the detected screen size is within the allowable size, it is recognized as one screen, the notch driving position is calculated as before, and it is registered in the notch driving position storage buffer. If the detection screen is not within the allowable size, further tolerance VBTL
If it is recognized as an exposed area, the part of the film surface that was recognized as an unexposed area with tolerance VBTH is corrected and then recognized as an exposed area again. That is, the counter 40 starts counting again, and the subsequent left side is detected.

If either the tolerance VBTL or VBTH is recognized as an unexposed area and the size verification result is not within the allowable range, it is registered in the exposure block buffer in the logical operation circuit 37 as an abnormal exposure block.

As explained above, in the screen position detection method and device of the present invention, there are two tolerances, VBTL and VBTL.
Since the exposed screen is detected by setting VBTH, compared to conventional screen position detection methods and devices that do not provide a tolerance or provide only a single tolerance, large blurring due to overexposure etc. It is possible to extremely accurately detect the position of the exposed screen when film base density unevenness is particularly large on one side of the screen, and to detect the properly exposed screen.
This does not reduce the detection accuracy of underexposed screens.

[Brief explanation of drawings]

1 and 2 are explanatory diagrams showing the deviation of the notch position on the film surface by the conventional screen position detection method and device, and FIG. 3 is a block diagram showing an example of the configuration of the screen position detection device of the present invention. 4 and 5 are explanatory diagrams showing the operation of detecting an exposure screen on a film surface by the screen position detection method and apparatus of the present invention. 36 is a screen density detector, 37 is a screen detection logical operation circuit, 39 is a distance monitoring counter, 40 is an exposure section accumulation counter, 41 is a notch driving circuit, 4
2 is a notch driving blade.

Claims (1)

[Claims] 1. Moves relative to a film such as a photograph, and provides tolerance for film base density unevenness, etc.
A film surface density detection means for detecting the density of the film surface based on VBTL and VBTH, which is a tolerance for blurring appearing at both ends of an overexposed screen; A first movement in which counting of the relative movement amount between the film surface density detection means and the film is started from the time when it is detected that the film surface density has become larger than the value obtained by adding the above-mentioned VBTL, and the counting is ended after a predetermined time elapses. After starting counting at the same time as the amount counting means and the first movement amount counting means, the film surface density detecting means determines that the density of the film surface is greater than the sum of the base density of the film and the VBTH within the predetermined time. If it is detected that the density has increased, the count is reset and starts counting again, and within the predetermined time, the film surface density detecting means detects that the film surface density has reached the base density of the film.
a second movement amount counting means that continues counting if it does not detect a value greater than the sum of VBTH; and an arithmetic means that calculates the center position of the screen based on the count value by the second counting means. A screen position detection device equipped with.