JPH03201785A - Color photofilm reader - Google Patents

Abstract

PURPOSE:To always obtain a best read signal by resetting a read level so that the read condition of each color signal is identical when a color photofilm is discriminated to be a negative film. CONSTITUTION:When a color photofilm is discriminated to be a negative film, the S/N difference based on an RGB signal level difference is averaged. That is, a storage time of a line sensor 6 is extended for a color signal (B color signal) with a low signal level, each color signal is set to a read level close to a saturation level of the line sensor 6 and each color signal is read with the best S/N. Moreover, a color temperature conversion filter 9b in which levels of RGB color signals are made nearly equal to each other to form a flat level and the state is used as a reference to set the read level. Thus, the best read signal is always obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a color photographic film reading device, and more particularly, to a color photographic film reading device configured to set an optimum reading level depending on the color photographic film to be read. Regarding reading devices.

(Prior Art) FIG. 8 is a block diagram of a general color photographic film reading device. The light from the light source 20 is condensed by a condensing lens 21 and transmitted through a color photographic film 22, and this transmitted light is sent to an imaging lens 23 and is focused on the imaging surface of an imaging device (for example, a line sensor or an area sensor such as a CCD) 24. imaged above. The transmitted light read by the image sensor 24 is converted into an electrical signal and sent to the next stage signal processing circuit 25.

Further, 26 is a diaphragm mechanism disposed on the optical path of the transmitted light, and the light amount of the light source 20, the type and exposure conditions of the color photographic film 22, various filters (not shown) disposed on the optical path, etc. The diaphragm mechanism 26 is adjusted according to the sensitivity of the image sensor 24, etc., and the reading level of transmitted light is set.

(Question 8 to be solved by the invention) In the conventional color photographic film reading device described above,
By manually adjusting the aperture mechanism 26, the photographic film 22
Since the reading level of the transmitted light from the sensor was set, it took time to set it up, and its accuracy was not very good.

In particular, the reading conditions may differ depending on whether the color photographic film 22 to be read is a reversal negative, and the optimum reading level may not be set for each color signal (for example, each RGB color signal). There was a problem that a difference occurred in the SN ratio.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a color photographic film reading device that reads color photographic films at a set reading level, as shown in FIGS. 1 and 2. means for statistically processing the signal level obtained by reading the transmitted light from the color photographic film to calculate the signal level from the maximum transmission part of the color photographic film (step 103); means for setting the reading level according to the signal level from the maximum transmission part of the color photographic film (step 104), and comparing the level of each color signal obtained by reading the transmitted light from the color photographic film. , means for determining whether the color photographic film is reversal or negative (step 105); and when it is determined that the color photographic film is reversal, the reading level is re-adjusted to be the same as the negative reading condition; means for setting the reading level (step 106); and means for resetting the reading level so that the reading conditions for each color signal are the same when the color photographic film is determined to be negative (step 10).
7) A color photographic film reading device comprising:

(Function) In the above color photographic film reading device, the reading level is automatically set according to the various conditions of the color photographic film to be read.

(Embodiment) An embodiment of the color photographic film reading device according to the present invention will be described in detail below with reference to the drawings.

First, the basic structure of a color photographic film reading device will be explained with reference to FIG.

After the light from the light source 1 is focused by a pair of condensing lenses 2 and 3, it is transmitted through a color photographic film 4, which is a transparent original, and this transmitted light is directed onto the imaging surface of a line sensor 6 by an imaging lens 5. imaged.

The line sensor 6 is a solid-state image sensor that is mechanically scanned (sub-scanned) in a direction perpendicular to its longitudinal direction (main-scanning direction) and reads surface information of the color photographic film 4.

7 is a heat ray absorption filter disposed between the condenser lenses 2 and 3, and 8 is an RGB switching filter. This RGB switching filter 8 changes the light from the light source 1 into R (red) and G (green).
, B (blue). Also, 9a, 9
b is a group of conversion filters which are appropriately arranged depending on the type (reversal or negative) of the color photographic film 4 to be read, as will be described in detail later.

Furthermore, 10 is a diaphragm (mechanism) disposed between the imaging lens 5 and the line sensor 6.

The line sensor 6 has its light reading period (light accumulation period) freely set by the line sensor storage circuit 11, and its sensitivity is adjusted. The output of the line sensor 6 is converted into a digital signal with a predetermined number of bits by the A/D conversion circuit 12 in the next stage, and then the output is converted into a digital signal with a predetermined number of bits.
, 14.15. Note that the output of the line sensor 6 is sent to a signal processing circuit (not shown) during actual reading.

Reference numeral 16 denotes a control calculation circuit (eg, CPU) that adjusts the signal level according to the flowchart shown in FIG.

The control calculation circuit 16 includes the preliminary scanning memories 13, 14, and 15.
Based on the processing results, the aperture 10 and the line sensor storage circuit 11 are controlled to comprehensively adjust and set the reading level. Furthermore, based on the processing result, it is determined whether the photographic film 4 is negative or universal, and the conversion filters 9a and 9b are appropriately arranged based on the determination result.

Next, the operation of the image reading apparatus configured as above will be explained with reference to the flowchart shown in FIG.

Prior to preliminary reading, a reading level is provisionally set (step 100). With the photographic film 4 removed from the optical path (this is approximately equal to the maximum transmission area of a reversal color photographic film), the signal level from the line sensor 6 is measured by the control calculation circuit 16. Based on this measurement result, the aperture (mechanism) is adjusted so that the line sensor 6 is at a (maximum) level at which it is not saturated.
10 and the line sensor storage circuit 11 adjust the amount of incident light and temporarily set the reading level.

Next, after the desired photographic film 4 is set, the R
The GB switching filter 8 is sequentially switched and preliminary reading of the photographic film 4 is executed (step 101).

The pre-read signal data is sequentially stored in the pre-scan memories 13, 14, 15 and pre-processed. The signal data for each pixel is subjected to averaging processing and median filter processing to reduce reading errors due to dust and the like (step 102).

As shown in FIG. 3, the preliminary reading range is set within the inner frame n, which is the maximum photographing frame N of the photographic film 4 reduced by 5 to 10%. Although the range actually read by the line sensor 6 may be adjusted to be within the inner frame n by optical zooming, only the signal data corresponding to the inner frame n may be used as the signal data for the preprocessing. Bye.

From the preprocessed signal data, a histogram as shown in FIG. 4 showing the relationship between brightness (luminance) and appearance rate is generated and statistically processed (step 103). When generating a histogram, signal data may be thinned out as appropriate.

From the generated histogram, the top 3-5% of brightness (
Find the average value of the bright areas). The average value of this bright area is used as the signal level of the maximum transmittance area of the photographic film 4 (corresponding to the white of the subject in reversal, and the black of the subject in negative) to set the reading level. That is, the reading level is set so that the average value of the bright portion becomes the maximum level at which the line sensor 6 is not saturated (step 104).

Specifically, the signal level m at the time of temporary setting and the average value M of the bright area
The line sensor storage time is changed using the diaphragm 10 and the line sensor storage circuit 11 so that the signal level from the line sensor 6 is M/m times higher than the temporary setting. to set the reading level. Note that the line sensor 6 may be moved to the position of the maximum transmission area, the signal level of the maximum transmission area of the photographic film 4 may be actually read, and this signal level may be adjusted to the maximum level at which the line sensor 6 is not saturated. .

Next, a description will be given of how to determine whether the photographic film 4 is negative or versatile. Figure 5 shows the spectral characteristics of the maximum transmission area of reversal color photographic film (corresponding to the white of the subject) as a dotted line, and the solid line represents the spectral characteristics of the maximum transmission area of negative (corresponding to the black of the subject). It is something that As is clear from the figure, the transmittance of negative photographic film decreases on the short wavelength side. As a result, in the light transmitted through the maximum transmittance portion of the negative photographic film, the signal levels of the RGB signals differ as shown in FIG. Therefore, by comparing the RGB color signal levels of the maximum transmission area obtained in the reading level adjustment process, for example, if the R signal and B signal levels are approximately equal, it is determined that the signal is universal, and by comparing it with the R signal level. If the level of the B signal is low, it is determined that the signal is negative (step 105). The above determination is executed by the control arithmetic circuit (CPU) 16 using signal data on the preliminary scanning memory 13, 14, 15. As shown in FIG. 7, the B signal level of the negative photographic film is:
Since it is smaller than the B level of reversal photographic film, the two may be compared for discrimination.

When it is determined that the color photographic film is reversal, the imaging conditions for the negative-taking version are made the same and adjusted to the characteristics of the negative so that the depth of field and light source are constant (step 106).

That is, a color temperature conversion filter 9a (indicated by a dash-dot line in FIG. 5) having substantially the same spectral characteristics as the unexposed portion of the negative is set between the condenser lenses 2 and 3.

Note that the storage time of the line sensor may be changed according to the RGB color signals to adjust the level of each RGB color signal to match the characteristics of the negative.

Further, when the color photographic film is determined to be negative, the SN ratio difference based on the RGB signal level difference shown in FIG. 6 is smoothed out (step 107). That is, for a color signal with a low signal level (such as a B color signal), the line sensor 6
By increasing the accumulation time of the line sensor 6 for each color signal,
The reading level is set close to the saturation level of the color signal, and each color signal is read so as to have the best signal-to-noise ratio. Also,
A color temperature conversion filter 9b may be provided so that the levels of RGB color signals are approximately equal, and the reading level may be set based on this flat state.

As described above, the read level adjustment based on the preliminary reading (preliminary scanning) is completed, and the actual reading of the color photographic film 4 is executed (step 108).

(Effects of the Invention) As described in detail above, according to the color photographic film reading device of the present invention, the reading level is set by calculating the signal level of the maximum transmission part of the color photographic film to be read, and further, It is determined whether the color photographic film to be read is reversal or negative, and the reading level is reset so that the reading conditions for both are time -, and the signal level of each color signal is time -. Since the read level is reset, the best read signal can always be obtained depending on the conditions of the color photographic film.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a color photographic film reading device according to the present invention, FIG. 2 is a flowchart showing the operation of the color photographic film reading device, and FIG. 3 is a reading during preliminary reading (preliminary scanning). Figure 4 is a histogram showing the level of the read signal, Figure 5 is a diagram showing the spectral characteristics of the maximum transmittance area of beam versal and negative, and Figure 6 is the output level of each color signal for negative. FIG. 7 is a diagram showing the output levels of the universal and negative B (blue) color signals, and FIG. 8 is a configuration diagram showing a conventional example. 4...Color photographic film, 6...Line sensor,
9a, 9b... Filter group, 10... Aperture (mechanism)
, 1 tri-line sensor storage circuit, 13.14.15... memory for preliminary scanning, 16...
Control calculation circuit. =(ttN-[) -110 2nd figure 2nd figure brightness 2nd figure [n(9) 1990 first month Σ

Claims (1)

[Scope of Claims] A color photographic film reading device for reading a color photographic film at a set reading level, comprising: statistically processing the level of a signal obtained by reading transmitted light from the color photographic film; means for calculating the signal level from the maximum transmission area of the color photographic film; means for setting the reading level according to the calculated signal level from the maximum transmission area of the color photographic film; means for determining whether the color photographic film is reversal or negative by comparing the levels of each color signal obtained by reading transmitted light; and when the color photographic film is determined to be reversal, reading the negative. and means for resetting the reading level so that the reading conditions for each color signal are the same when the color photographic film is determined to be negative. A color photographic film reading device characterized by: