DE329273C - Process for producing the yellow partial image for subtractive three-color photographs - Google Patents

Description

Process for the production of the yellow partial image for subtractive three-color photographs. The invention relates to the production of peculiar yellow partial images for the subtractive Three color photography in conjunction with the red and blue part positives A better reproduction of the natural color tones than before can be achieved; the Invention is based on the following observation: 'A copy of the yellow negative of a Set of negatives for a three-color photograph, the one with ordinary, especially blue-sensitive -Emulsion is obtained without a color filter, represents a black and white image, in which, however, by highlighting the yellow that contains the yellow partial image. So it can: without having to make a special picture, a black and white picture with a of the three partial images of a three-color frame for photographs in natural colors be united.

If you now in the production of the yellow partial image from one of the such a negative made silver copy by bleaching the same with, for example a solution of a ferricyanide and then toning the bleached image with a solution of mercury salts, the bleaching continues only so far that the Image only partially disappears; so you get a yellow picture afterwards, which apart from the yellow color values of the recorded object also its drawing and reproduces shadow tones in a faint gray image.

If now such a yellow image: with the red and blue partial positives united by layering. is, so you get - a color photograph, in which the reproduction of the colors is more natural than the usual three Partial images, created color photographs, what mainly the gray image is attributed, which is present next to the yellow image.

For example, a. Bromide silver or chlorine-bromide print made from the yellow negative; that used to make the copy Paper should expediently be parchmented or otherwise suitable for prevention be pretreated for warping. This copy is then used in one of the following. Solutions bleached, depending on whether a pure yellow or a reddish yellow is obtained want.

a) i part of a 5 percent potassium ferricyanide solution, 1 part of a 5 percent potassium bromide solution, or - b) 3o parts. a 5 percent lead nitrate solution;) `i: Ara k- rs -iö @ ei @ e, an iQpro7, entigen potassium- 10 parts of an 10 percent aluminum nitrate solution, 1 part nitric acid, -15 parts acetic acid, 50 parts water.

The bleaching continues until a pale gray. Image remains, whereupon the copy after washing in a clay bath with the following composition is brought: q: o parts of a 5 percent mercury chloride solution, 6o parts of a 8 percent potassium iodine solution.

As soon as the trigger has achieved the desired tone, it becomes from the The bath was taken out and washed in the usual way. It should be noted that the yellow tone after taking the copy out of the bathroom continues a little developed, and must be used in deciding when to remove the trigger should be taken into account accordingly. The development of the yellow tone can but interrupted at every point in the toning process by immersing the fume cupboard in an acid bath ' will. In this way a print of a suitable yellow color is obtained; which corresponds to the yellow parts of the image to be produced, and which one moreover contains gray base image.

Claims (1)

PATENT CLAIM: Process for the production of the yellow partial image for subtractive three-color photographs, characterized in that a silver copy is produced from a negative obtained with an ordinary, particularly blue-sensitive emulsion without a color filter - this only bleaches so far that a pale gray image of the entire object remains, and then tones it yellow in a known manner with the help of iodine mercury.