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Dave Schrader wrote about masking several weeks ago and I sent the response below. Dave has been trying to post an excellent response without any success so I will try to post his detailed and informative answer. Thanks Dave! It failed for me too. I do not know if there is a size limit and that is wy it does not show up. This time, I am splitting it in four parts and hopefully it will work. Bertho =============================================== <<<< My previous posting: >>>>> This bit of information is intriguing. I am trying to design color filters using printers and a clear transparency film. It sort of looks like an overhead transparency. My goal is to be able to select different colors and have as low transmission loss as possible for that selected color (wave length) and suppress the other wave lengths as much as possible. I have the proper spectrometric equipment to measure the printed films. I understand the need for black in the printers and why it is used but part of your description triggered my interest. Now finally the questions: What is masking and how is it used? Any suggested reading material for really understanding the different ink processes. TIA Bertho Boman ======================================== Dear Bertho, Sorry for the late reply. I attempted to post this several times to the Inkjet list, but for whatever reason it never appeared. I'm guessing that I was censored by the list owner; maybe the content is too far off track? I e-mailed Leben directly but he never replied so I gave up. Kind of makes me mad, but it's out of my control so no sense in losing any sleep over it. Anyway, here's the response that I wrote to the list in regards to your questions: (From 5/6/02): Wow, your questions cover a lot of ground, but I'll give it a shot. I'll try and describe a basic color masking scheme that I used to employ back in my dye transfer days. So here goes: The term masking can cover a lot of different areas. In dye transfer, there's overall contrast reduction masking, highlight masking, specular highlight masking, and color-correction masking. There's also various masking schemes that apply specifically to offset (which fortunately is built into separations automatically so we don't have to mush our brains thinking about it). All processes that use the subtractive primaries (cyan, magenta, and yellow) to reproduce color require masking of some form. In our Epson inkjet printers, "masking" is performed electronically via the print driver and we never have to give it a second thought. And probably the most important type of masking is for color correction. Here's the problem: the color dyes and inks that make up our photographic world are far from perfect. Whether it be the dyes in Ektacolor prints, Ilfochrome prints, offset lithography inks, Epson inks, you name it; cyan, magenta, and yellow all have spectral deficiencies; you'll see this described in books as dye deficiencies, but it applies equally to inks if not more so. The problem isn't so much in originals (i.e. slides) but rears its ugly head when we try to reproduce them. So here's what's going on: <<<<< to be continued >>>>> - Turn off HTML mail features. Keep quoted material short. Use accurate subject lines. http://www.leben.com/lists for list instructions.