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  1. #1
    Join Date
    Aug 2000
    Location
    Placitas, New Mexico, USA
    Posts
    38,234

    Default Color Model Stereograms

    Revisted Additive and Subtractive Color Models for two new stereograms. For the CMYK (the four colors used in desktop and commercial printing) I made a separate layer for each color and angled the screens at the precise angles and applied Multiply (Stained Glass) transparency. Just like the 4 color printing process.

    I always have trouble remembering which model is Additive and which model is Subtractive.

    Adding Cyan, Magenta, Yellow & and black transparent inks produces black. Subtracting Red, Green, and Blue light (as in display pixels) produces black. That is the official theory.

    But if you subtract CYM & K you get white and if you add 100% RG & B light you get white. So this is why it is confusing.

    Also where the CM & Y overlap you get Red Green and Blue and combining Red Green and Blue lights in 100% amounts can produce Cyan, Magenta, and Yellow. It's a miracle no?
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    Gary W. Priester
    Mr. Moderator Emeritus Dude
    , Sir

    gwpriester.com | Custom-Stereograms.com | eyeTricks on Facebook






  2. #2
    Join Date
    Apr 2012
    Location
    SW England
    Posts
    11,769

    Default Re: Color Model Stereograms

    Quote Originally Posted by gwpriester View Post
    Revisted Additive and Subtractive Color Models for two new stereograms. For the CMYK (the four colors used in desktop and commercial printing) I made a separate layer for each color and angled the screens at the precise angles and applied Multiply (Stained Glass) transparency. Just like the 4 color printing process.

    I always have trouble remembering which model is Additive and which model is Subtractive.

    Adding Cyan, Magenta, Yellow & and black transparent inks produces black. Subtracting Red, Green, and Blue light (as in display pixels) produces black. That is the official theory.

    But if you subtract CYM & K you get white and if you add 100% RG & B light you get white. So this is why it is confusing.

    Also where the CM & Y overlap you get Red Green and Blue and combining Red Green and Blue lights in 100% amounts can produce Cyan, Magenta, and Yellow. It's a miracle no?
    Wow #3 Gary! It's like Woodstock all over again.
    I can remember it so clearly as if I wasn't there.

    Deep, man.

    Acorn
    Acorn - installed and active Xara software: Cloud+/Pro+, XDPX, XWD Premium 15 & 12, XPGD10, X3D7, Xara Xtreme 5, back through time (to CC's Artworks).
    Raise software faults with MagiXara: http://support.magix.net/; if Cloud+/Pro+: https://xara.com/contact-us/

  3. #3
    Join Date
    Mar 2009
    Posts
    3,558

    Default Re: Color Model Stereograms

    Yes, that third one is beautiful and pops out so clearly!

  4. #4
    Join Date
    May 2014
    Location
    Australia: GMT+10
    Posts
    201

    Default Re: Color Model Stereograms

    Quote Originally Posted by Boy View Post
    Yes, that third one is beautiful and pops out so clearly!
    +1

  5. #5
    Join Date
    Feb 2007
    Location
    UK
    Posts
    17,695

    Default Re: Color Model Stereograms

    I always have trouble remembering which model is Additive and which model is Subtractive.
    Subtractive colour is when some wavelengths are removed between the light source and your eye - this happens when light bounces off pigment [which absorbs some wavelengths] - one of the reasons you will never get white if you mix paint colours

    Additive colour is when wavelengths are radiated from a light source and reach the eye without loss, a specific mix of wavelengths resulting in specific colour [or a specific prismatic split]

    so as an artist painting with watercolor on paper I have to bear in mind that I will never be able to paint the sky or the sun realistically as they are additive and my paint is subtractive

    it can get confusing when your additive primaries, RGB, are used to stimulate the subractive primaries CMY[K] on a computer, which I guess is what your OP is referring to; but on the basis of what I understand and was taught as a painter I do not really agree with your first attachment - glad that I can stick to RGB on the computer and let others worry about CMYK

    I think on a computer if you subtract CMYK you get white because the computer assumes your [virtual] paper is white, which is how white it is done in print; RGB combined is white because it is additive and therefore effectively the reverse of splitting light with a prism

    which begs the question how come the paper is white.... well it's never pure white of course, it's treated so that it relects as much light as possible, traditionally in our culture by adding chalk to the mix; and then it can also be coated
    is chalk pure white... no, but you would have to look very closely to see this, and so, if the paper is made well and the chalk fine the same applies [and white pigment too]
    perception loves the general case....

    where was I... oh yes - having a lot more difficulty than usual seeing these stereograms Gary, unfortunaely... maybe the woodstock days are behind me...
    Last edited by handrawn; 09 July 2020 at 10:43 AM. Reason: woodsock !!!!
    -------------------------------
    carpe diem
    carpo vitae

 

 

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