CA2228690A1

CA2228690A1 - Method for preparing full color posters of very high quality and sharpness

Info

Publication number: CA2228690A1
Application number: CA 2228690
Authority: CA
Inventors: John O. Kobel
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-03-05
Filing date: 1998-03-05
Publication date: 1999-09-05
Also published as: WO1999045432A1; AU3243899A

Description

METHOD FOR PREPARING FULL COLOR POSTERS OF
VERY HIGH QUALITY AND SHARPNESS
This invention is concerned with a method for preparing full color posters of vend high quality and sharpness on standard photographic papers.
To prepare a quality full color poster from any digitized image, with or without text, it is of conventional practice to produce full-sized color separation negatives of the scanned original art work, and then to use these separation negatives to produce the poster either by contact on a photographic paper, by serigraphy, or by four-color process printing.
This conventional method is efficient but quite expensive if the number of posters to be prepared is small.
It has now been discovered that full color posters can easily be prepared in small numbers at a substantially lower cost by a method comprising the steps of:
a) producing color separation negatives of the digital file to be reproduced as a poster, these negatives being usually four in number and of full size, or sized to fit a photographic enlarger (4" x 5" to 11" x 14" in size);
b) producing the corresponding color separation positives of the color separation negatives produced in step (a);
c) printing the separation positives in successive order by direct application and exposition of each of the same onto a display transparency film or color negative material so as to form a full color negative;
d) exposing the full color negative obtained in step (c) to a tinted light in order to vary the base color of this negative as much as necessary to obtain any requested color tone; and e) using the exposed full color negative of step (d) to produce the requested reproduction, i.e. the requested poster, either of the same size or of an enlarged size, in much the same way as a conventional continuous-tone color negative would be used.

2 The same results may be achieved by directly producing color separation positives of the digital file, instead of producing color separation negatives as called for in step (a) and thereafter producing the corresponding color separation positives as called for in step (b). In such a variant, steps (c) through (e) remain the same.
It has also been found that it is possible to change the optics of an existing imagesetter of the same type as conventionally used to produce color separ~~tion negatives or positives, in order to mechanically combine steps (a) through (c), thereby producing a single screened film with all four colors printed on it - in other words, a full color screened negative.
The display transparency film sold by KODAK under the trademark DURP,CLEAR has proved in practice to be particularly useful to produce the full color negative disclosed in step (c) or in the converted imagesetter. Other types of clear base photographic products can be used but have proved so far not to give as good results. Color negative material can be used but it is generally less precise, and produces less sharp prints.
The above method has been tested with great success, using digital files of a minimum of ten (10) MB. It allows the production of large, full color posters of vend high quality and sharpness from digital files, small or large, in a very simples yet efficient manner.