NL7903072A - DEVICE FOR PRINTING PHOTOGRAPHIC COLOR NEGATIVES. - Google Patents

Description

E 5586-1 *

P&C

Gunther Palm in Voorburg, the Netherlands

Device for printing photographic color negatives.

The invention relates to an apparatus for printing photographic color negatives, having a measuring device for the color values of the film to be printed, which determines the filter settings to be used in printing. Such printing equipment is widely used by finishing centers. The filter settings to be used depend on various factors.

A first factor is the type of paper on which is printed. This is usually constant, so that constant filter settings could be used in this regard. However, another factor determining the desired filter settings is the nature of the films to be processed. Since finishing plants offer a wide variety of brands and types of films, while the color values of the negatives of different brands and types of films vary widely, different filter settings are required for each brand and type of film. Therefore, the color values of each negative to be printed are usually measured, and the measurement results determine the filter settings to be used when printing that negative. However, the measurement result is not only influenced by the properties of the relevant brand and type of film, but also by the nature of the recording. Depending on the main subject of the recording (blue sky, green meadow, yellow beach), but also depending on the type of light used in the recording (sunlight, flash light, incandescent light, candlelight), a certain color will often be overrepresented or underrepresented in the color negative and this influences the measurement results and, therefore, the selected filter settings, without there being essentially any reason to do so. After all, there is no reason to weaken the color blue by means of a certain filter setting if the image to be printed consists largely of a blue sky. Extremely complex measuring devices 30 have therefore been developed, which are capable of independently determining whether a particular color is rightly overrepresented or underrepresented and which in that case omit correction. Measuring devices have also been developed that take into account only the measured total density of each negative and do not respond to the underrepresented or 7903072 .S 2 '' ié ί * overrepresented of certain colors. However, such devices are only suitable for printing negatives of a certain brand and type of film, since the color values of different brands and types of film differ greatly from each other, even if these are otherwise identical images. Such devices must be switched for other brands and types of film, so that they cannot process different brands and types of film without a different switch for each film.

The object of the invention is to provide a device of the type described above which can process any brand and type of film, if properly developed, without the need to perform a switch for each brand and type of film. The brand and type of the film need not even be known.

The invention is based on the insight that color-positive films, provided they are not too old, have been stored and exposed in a reasonable manner and have been developed correctly, always provide images with an acceptable color balance, without any correction being necessary . Since such films are developed with a standard process (whereby the process used must of course be adapted to the make and type of the film), a correction is not even possible.

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The same may therefore be expected from the actual color negative image of a color negative film. Here, too, the color negative image exhibits an acceptable color balance, provided the film is not too old, has been reasonably stored and exposed, and has been properly developed. That nevertheless, when printing different brands and types of film, completely different filter settings are necessary in order to obtain a good, color balance of the prints, this is due solely to the fact that, in contrast to color slide films, color relief films are provided with a color mask which arises during the development and whose color varies widely for different brands and types of film.

A good color balance of the deduction is therefore ensured if filter settings are chosen when printing that compensate for the presence of the color mask. The color mask is found in pure form (unaffected by the negative images on the film) on unexposed parts of the developed film, and therefore a measurement of unexposed parts of the developed film yields measurement results 7S03OJ2

Claims (4)

In addition to the measurement described above in order to achieve a correction of the influence of the color mask, if desired, a measurement can be made in the usual manner of the density of the various negative images in order to obtain a correction for overexposure or underexposure of the relevant negative image and, moreover, Color measurements on the negative images are used to correct for the overrepresentation or underrepresentation of certain colors in the image by varying the filter settings, caused, for example, by the nature of the light used in the recording. 30 CONCLUSIONS: 1. Apparatus for printing photographic clay negatives, having a measuring device for the color values of the film to be printed, which determines filter settings to be used in printing, characterized in that the measuring device determines the filter settings on the basis of the measurement results of an unexposed part of the developed film. 2. Device according to claim 1, characterized in that the measuring device 7903072 - X. perform a measurement on an unexposed portion of the leader strip of each film. Device as claimed in claim 1, characterized in that the measuring device performs a measurement on an unexposed part between two images of each film. Device according to claim 1, characterized in that the measuring device performs a measurement on an unexposed part next to the image series of each film. 7903072