JPH0721618B2 - Photo printing method - Google Patents

Description

The present invention relates to an improvement in a photographic printing method using a CRT as a printing light source.

[Conventional technology]

A CRT is used as a printing light source, a photographic film such as a negative film is arranged in front of this CRT, and a negative image recorded on the CRT is illuminated with a flying spot light so as to be printed on a photosensitive material such as photographic paper. Is known (for example, Japanese Patent Publication No. 45-5336).

Photographic printing is also known in which sharp-cut color filters of yellow, magenta, and cyan are used, white exposure is first performed, and then the color filters are inserted into the printing optical path for subtractive color exposure. In this subtractive color photographic printing, a yellow filter is inserted in the printing optical path when the color exposure is stopped, a magenta filter is inserted when the green exposure is stopped, and a cyan filter is stopped when the red exposure is stopped. Is inserted.

[Problems to be solved by the invention]

When a CRT is used as the printing light source in photoprinting with the subtractive color method, when a flying spot light is scanning in the middle of the screen, if a color filter is inserted in the printing optical path, CR
Exposure unevenness occurs because the number of exposure frames differs depending on the position of T on the screen. In order to prevent the occurrence of this exposure unevenness, the exposure time may be rounded up or down and each color filter may be inserted during the blanking period. However, if the exposure time is increased or decreased in this way, the exposure amount of each color deviates from an appropriate value, and the color balance deteriorates.

Furthermore, if a high-intensity CRT is used to perform photo printing in a short time, the amount of light emission per frame increases,
When the exposure time is controlled in the frame cycle, the number of exposure steps becomes coarse, and it becomes impossible to finely adjust the color balance.

[Object of the Invention]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a photographic printing method capable of preventing uneven exposure, improving color balance, and finely adjusting the color balance.

[Means for solving problems]

In order to achieve the above object, the present invention provides a CRT exposure time for white exposure without inserting three types of color filters into a printing optical path and with subtractive color exposure with at least one color filter inserted in a printing optical path. The light emission brightness of the CRT is changed so as to be an integral multiple of the frame period of.

[Action]

Since the light emission brightness of the CRT is changed between the white exposure and the color reduction exposure, the exposure amount of each color can be accurately controlled to improve the color balance, and the color balance can be finely adjusted. Further, since the light emission luminance is changed so that the exposure time becomes an integral multiple of the CRT frame period, the exposure unevenness caused by the scanning exposure of the flying spot light is eliminated.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

〔Example〕

In FIG. 1, a negative carrier 11 is arranged on a black and white CRT 10, on which a color negative film 12 is slidably set. At the time of printing a negative image, the CRT 10 emits light by the driver 1 to illuminate the color negative film 12. The light transmitted through the color negative film 12 is imaged on the photographic paper 16 by the printing lens 15 while the shutter 14 is open. A cyan filter 17, a magenta filter 18, and a yellow filter 19 are arranged between the printing lens 15 and the shutter 14, and the filters 17 to 19 for the respective colors are inserted into the printing optical path by the filter driving unit 20. In addition,
The shutter drive unit 21 controls opening / closing of the shutter 14.

The photographic printing paper 16 is pulled out from the photographic printing paper roller 25 by a pair of drawing rollers 24, and is sent to an exposure position formed by a mask 27 via a guide roller 26. The photographic printing paper 16 exposed at this exposure position is sent by a feed roller 28 to a winding section or a photographic developing section (not shown).

A red photometry unit 30, a green photometry unit 31, and a blue photometry unit 32 are arranged diagonally above the negative carrier 11 and measure a part of the light transmitted through the negative image. These photometric units 30-
The output signal of 32 is digitally converted for each color by the A / D converter 33, and then taken into the controller 34. The controller 34 calculates the three-color exposure amount using a well-known exposure arithmetic expression having the average transmission density as a variable. Also the controller
34 is the light emission brightness of the CRT during white exposure from the three-color exposure amount,
It controls the emission brightness when the color filters 17 to 19 are inserted and when the color filters 17 to 19 are inserted. The signal representing the emission brightness is sent to the brightness adjustment circuit 35.

The keyboard 36 has various keys and gives necessary instructions to the controller 34. Further, the keyboard 36 is provided with well-known density correction keys, color correction keys, correction keys, function keys, etc., which are empirical for a negative image in which subject feria may occur in automatic control. It is possible to input the correction amount defined in.

Next, the operation of the above device will be described with reference to FIGS. 2 and 3. First, the color negative film 12 to be printed is set on the negative carrier 11. When the power is turned on, the brightness adjusting circuit 35 causes the CRT 10 to emit light at the reference brightness L _W and illuminate the color negative film 12. A part of the light transmitted through the color negative film 12 enters the photometric units 30 to 32 and is photoelectrically converted. The output signals of the photometry units 30-32 are
Controller 3 after digital conversion by A / D converter 33
It is taken into 4 and converted into the average transmission density here. Using this average transmission density, the exposure amounts for red, green and blue are calculated respectively. Further, when the keyboard 36 is operated to input the density or the color correction amount, it is added to the automatically calculated exposure amount.

As shown in FIG. 2, the controller 34 obtains the minimum value of the three-color exposure amount and sets it as the white exposure amount E _W. At the time of white exposure, the CRT10 emits light with the reference brightness L _W.
Since the light emission amount per frame is known, the white exposure amount E _W is divided by this to obtain the number N _W of white exposure frames. Here, if it is not divisible, the number of frames may be rounded up or down, but if the density is appropriate, the light emission luminance of the CRT 10 is reduced to make divisible.

In this embodiment, since the red exposure amount is the largest and the blue exposure amount is the smallest, the white exposure amount E _W is subtracted from the red exposure amount and the green exposure amount, respectively, and the common exposure amount E _GR is calculated. The common exposure amount E _GR is given by subtractive color exposure, but in this case, the emission brightness of the CRT 10 is reduced to L _GR in order to reduce the adjustment step of the exposure amount. Since the amount of light emission per frame at the time of dimming is known, the number of frames N _GR can be obtained by dividing the common exposure amount E _GR by this. The emission brightness is adjusted also when the number of frames N _GR is calculated. Next, by subtracting the white exposure amount E _W and the common exposure amount E _GR from the red exposure amount, the monochromatic exposure amount E _R is obtained. From the light emission luminance L _R of the CRT 10 during this monochromatic exposure,
Calculate the number of frames N _R.

When the keyboard 36 is operated to instruct the photo printing, the controller 34 sends a signal to the shutter drive unit 21 to open the shutter 14 at a timing synchronized with the vertical synchronization signal from the driver 13. When the shutter 14 is opened, the color negative film 12 is illuminated with the white light emitted from the CRT 10 which is emitting light at the reference brightness L _W. The negative image of the color negative film 12 is formed on the photographic paper 16 by the printing lens 15.

During white exposure, the controller 34 counts the vertical synchronizing signal to check the number of frames, and when the number of exposed frames reaches N _W , sends a signal to the filter driving unit 20 to turn yellow, as shown in FIG. The filter 19 is inserted into the printing optical path to stop the blue exposure.

When the yellow filter 19 is inserted, the controller 34 sends a signal to the brightness adjusting circuit 35 to reduce the emission brightness of the CRT 10 to L _GR . When the number of exposure frames reaches N _GR during the dimming, the controller 34 inserts the magenta filter 18 into the printing optical path and stops the green exposure. At the same time, the controller 34 sets the light emission brightness of the CRT 10 to L _R. Then, when the number of exposed frames reaches N _R , the cyan filter 17 is inserted into the printing optical path to stop the red exposure. At the time of inserting the cyan filter 17 or immediately thereafter, the shutter 14 is inserted into the printing optical path via the shutter drive unit 21, and the color filters 17 to 19 are retracted from the printing optical path instead.

After printing the color image, the pull-out roller 24 rotates to pull out the photographic paper roll 25 or the unexposed portion for one frame and set it at the exposure position. The exposed portion is sent to the winding section or the photo developing section.

In this embodiment, two color filters are combined to substitute for a red filter, a green filter, and a blue filter, and a video signal is input to the driver 13 to sequentially expose three color planes by an additive method. It is also possible to print the video image on the photographic paper 16 with.

〔The invention's effect〕

As described above in detail, the present invention, during white exposure without inserting the color filter into the printing optical path, and during subtractive exposure with the color filter inserted into the printing optical path, the exposure time is an integral multiple of the frame period of the CRT. As described above, since the emission brightness of the CRT is changed, even if the CRT is used as a light source, the color image recorded on the original image can be printed by exposure without unevenness of exposure. That is, when using a CRT as the light source,
If the color filter is inserted into the printing optical path while the flying spot light is scanning in the middle of the screen, the number of exposure frames varies depending on the position of the CRT on the screen, and uneven exposure occurs, but this is eliminated. This allows
Color balance can be improved.

Further, since the light emission brightness of the CRT is changed between the white exposure and the color reduction exposure, the number of steps for adjusting the exposure amount can be reduced, and the color balance can be finely adjusted. In particular, by lowering the emission brightness of the CRT at the time of color reduction exposure as compared with that at the time of white exposure, fine adjustment of the color balance can be better performed.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a photographic printing apparatus embodying the present invention. FIG. 2 is an explanatory diagram showing the three-color exposure amount. FIG. 3 is a timing chart showing a photograph printing state. 10 …… CRT 12 …… Color negative film 14 …… Shutter 16 …… Printing paper 17 …… Cyan filter 18 …… Magenta filter 19 …… Yellow filter

Claims (2)

[Claims] 1. A photographic printing method in which a CRT is used as a printing light source, yellow, magenta, and cyan color filters are inserted into a printing optical path to print a color image recorded on an original image on a photosensitive material. The CRT emission brightness is adjusted so that the exposure time is an integral multiple of the CRT frame cycle during white exposure without inserting the filter in the printing optical path and during subtractive exposure with at least one color filter inserted in the printing optical path. A photo printing method characterized by being changed. 2. The CR during the subtractive color exposure is more than the CR during the white color exposure.
The photographic printing method according to claim 1, wherein the emission brightness of T is lowered.