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Adding white to a transparent film for laser printing

Nov 11, 2012, 13:25
Post: #1
Adding white to a transparent film for laser printing
The attached file shows the front castle of a ship with two ranges of windows on its white wall. I am trying to print this image with a laser printer on a transparent film while keeping the original white of the wall, letting only the windows inside their black frame transparent (the first two window frames of the upper row on starboard have been filled with a greyish tone merely as an experiment) - as if that transparent were projected on a dark surface rather than on a white one.

My question, which will probably sound completely absurd to anyone used to the RGB combination of colours is: since the addition of all colours (i.e. 255) is equal to white and therefore to transparency (or to the absence of colours), and since transparency will show as, well, transparency when printed on a transparent film, how can white - in this case the white background of the wall - still be added to the transparent film while keeping only the windows inside their frame transparent?

All my attempts with a variety of painting tools (including those of Mypaint) and profiles failed. Should this be done with two different layers instead?

Any help or advice will be very much appreciated.


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Nov 11, 2012, 16:28
Post: #2
RE: Adding white to a transparent film for laser printing
(Nov 11, 2012 14:05)ofnuts Wrote:  There is no concept of "transparency" in printing (at least not with consumer grade products). Printers and print drivers expect to be used with white paper to they don't print anything for white(*), so if your ship had of some solid color, having white windows would do the trick, but since your ship is white it would all be transparent.

In fact you can't print white on a transparent sheet... because no combination of your printer colors will produce white: even though RGB processing as done by Gimp is "additive" (you obtain yellow by adding red and green to black), printing is subtractive: you obtain yellow by removing cyan and magenta from white, and adding up the colors from the three cartridges produces black ( a not very clean black in practice, which is why you usually have also a pure black cartridge).

(*) this also applies to transparencies, since they are projected on a white screen...

Thank you Ofnuts. This is what I suspected, unfortunately.
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Nov 12, 2012, 19:38
Post: #3
RE: Adding white to a transparent film for laser printing
(Nov 12, 2012 14:03)paynekj Wrote:  I've come across the idea of printing white in the realm of model making (printing decal sheets), but according to this article I googled-up ALPS printers are no-longer made: http://desktoppub.about.com/cs/printing/f/white_ink.htm

Kevin

Thanks for this very intersting link (I also once had an ALPS printer, which is no longer made and I don't know of any other printers that could process white on a transparent support. As the article from 'About.com' suggests, the answer is that there are none).

Model making is precisely the field of application I am concerned with and most, if not all techniques described in the 'About.com' article seem relevant to it. However, none of them look trivial - notwithstanding the fact that they probably could not be applied in conjunction with GIMP - and I would have to enquire more about their use and cost.

Meanwhile, thank you again for your information.
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Nov 13, 2012, 08:42
Post: #4
RE: Adding white to a transparent film for laser printing
(Nov 12, 2012 20:45)paynekj Wrote:  Continuing on with the thought, as you can get multi-tone blank inks for creating black and white photographic prints, someone must have done something similar and made a white ink? So I googled white inkjet and found:
http://www.britmodeller.com/forums/index...opic=45423

And it appears Epson make a printer that prints white: http://www.epson.com/cgi-bin/Store/jsp/P...on.new=Yes

Good to know that a solution exists, after all. But until I can find the lucky owner of an Epson SP WT7900, I'm afraid I'll have to abide to the last tip given in the 'About.com' story, namely handpainting.

Thanks nonetheless.
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