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Thread: Too much cyan in real colour blending mode

  1. #1
    Join Date
    Apr 2009
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    Too much cyan in real colour blending mode

    I seem to get entirely too much of the colour cyan when using real colour blending.

    As you can see in the first attached image, wet green plus wet blue results in cyan, and so does wet blue plus wet yellow. If I keep moving the brush, most of the time, the cyan will eventually disappear. With real colour blending switched off I get the familiar mushy grey from most combinations. The example is in watercolour but it also happens with the oil brush. It's possible to get pure cyan or pure white (depending on some random factor I haven't identified) by continuing to lay on paint in circles.

    The second attached image shows a similar effect where the cyan doesn't immediately appear. It doesn't always turn out like this and different shades of red or green give different results. On the left is the starting situation and on the right is what happens when I continue laying on green paint. Sometimes the cyan is less pronounced, and sometimes I eventually get pure white. This also happens with watercolours, but is harder to see and easier if "Paper Wet" is enabled.

    The easiest way for me to reproduce this is as follows:

    0) select oil brush at 100% size
    1a) either pick bright saturated blue blue,
    1b) or pick a bright saturated red close to the top of the colour picker's range (i.e. on the violet side of red, not the yellow side)
    2) paint a stroke somewhere on the canvas
    3) pick a bright saturated green
    4) paint a stroke next to the red or blue one
    5) draw circles in the middle of the two strokes, if it doesn't quickly turn bright cyan, try again

    I'm still on a Mac with Mac OS X 10.6. Oil brush settings appear to be 99% load, 8% thinners, 50% pressure, auto-clean on as of now.
    Attached Images Attached Images   

  2. #2
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    Here is a link to a picture in ArtRage format with which I can reproduce this reliably by making circles in the middle of either of the two painted areas with the flat palette knife:

    http://discordia.erinye.com/toomuchcyan.ptg

  3. #3
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    Yellow and magenta NO red. :(

    Nice topic.

    If you mix cyan and magenta you get blue in real-mixing.
    And yellow and cyan is green.
    In normal-mixing it is light-blue and light-red.

    But where is red? If you mix yellow and magenta you must get red.
    But it is grey.

  4. #4
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    Real colour blending currently has some inconsistencies in certain high-saturated colour combinations. We're looking to improve it, and make it more flexible for artists using different media.
    AndyRage's mantra for graphics engine code:
    "Sure - how hard can it be?"

  5. #5
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    Only with the felt pen you get red.

  6. #6
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    Quote Originally Posted by michal View Post
    But where is red? If you mix yellow and magenta you must get red.
    With primary magenta, such as used in print, you should get red. My real-life primary magenta does produce red with yellow too. And of course my printer does.

    If you strictly work with the traditional red-yellow-blue system that we learn in school, where your magenta really is secondary violet mixed from red and blue, adding in yellow will however produce brown or grey as it does in ArtRage. (It should be noted that my watercolor pencils produce beautiful browns where AR only comes up with mushy grey )

    I tried with the felt pen as per your suggestion, but I only get traces of red, and only if I turn off Art Pen mode. So I'm guessing this is not really mixed red, but rather a result of the non-opaque colour. I get mushy grey in this mode if I apply more colour.

    Most of the real color blending in AR seems to follow what I would expect from mixing RYB colours in real life, but unlike real life, with no other primary colours available. There are two problems with it:

    1) It just seems that the resulting brightness is slightly off in some cases, and this effect is more pronounced when the colours are bright and saturated. For example, mixing secondary green and primary blue should result in aquamarine, but somewhere about halfway on the brightness scale in the colour picker, mixing green and blue starts to produce bright cyan that appears to become brighter the more colour you mix in. Nothing like this appears to happen when I try to mix any of the other RYB tertiary colours, though.

    2) While this is already a huge improvement over anything else I have available, I would of course prefer if I could have more primary colours. In real life I can have more than three and I can choose which ones I use. I realise it's not easy to implement this, I only know one other publicly available painting software that implements realistic color mixing (KDE Krita) and there, the realistic mixing part is currently not working at all and I don't know if it is even different from what AR does.

    I guess the real problem is that the only way to make this accurate is scanning huge amounts of manually painted sheets and then locating the closest matches when simulating mixing... hm, now this is something to think about, as it would let us use real paints to create lookup tables for our favourite real-world paints and use their mixing behaviour in AR ;-)

  7. #7
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    Click image for larger version. 

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    If find this a real big problem. I dont know why only just red doesnt work.
    Maybe an error in the algoritme of real color blending?

  8. #8
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    Quote Originally Posted by Danny the Fool View Post
    With primary magenta, such as used in print, you should get red. My real-life primary magenta does produce red with yellow too. And of course my printer does.
    -In airbrush you see also red because is more yellow pixel to the magenta pixel than real blending.


    If you strictly work with the traditional red-yellow-blue system that we learn in school, where your magenta really is secondary violet mixed from red and blue, adding in yellow will however produce brown or grey as it does in ArtRage. (It should be noted that my watercolor pencils produce beautiful browns where AR only comes up with mushy grey )
    -Strange :s a second error?

    I tried with the felt pen as per your suggestion, but I only get traces of red, and only if I turn off Art Pen mode.
    -Yes that is true. Maybe the blending is different.
    -The art pen you get Grey.

    So I'm guessing this is not really mixed red, but rather a result of the non-opaque colour. I get mushy grey in this mode if I apply more colour.
    -Ok

    Most of the real color blending in AR seems to follow what I would expect from mixing RYB colours in real life, but unlike real life, with no other primary colours available. There are two problems with it:
    -But cyan and magenta is beautiful blue. So blue is not a primaire color in RCB(Real color blending) . What i suppose.

    1) It just seems that the resulting brightness is slightly off in some cases, and this effect is more pronounced when the colours are bright and saturated. For example, mixing secondary green and primary blue should result in aquamarine, but somewhere about halfway on the brightness scale in the colour picker, mixing green and blue starts to produce bright cyan that appears to become brighter the more colour you mix in. Nothing like this appears to happen when I try to mix any of the other RYB tertiary colours, though.
    -Ok that is good point. But maybe they use the CYM spectrum en not the RYB spectrum.

    2) While this is already a huge improvement over anything else I have available, I would of course prefer if I could have more primary colours. In real life I can have more than three and I can choose which ones I use. I realise it's not easy to implement this, I only know one other publicly available painting software that implements realistic color mixing (KDE Krita) and there, the realistic mixing part is currently not working at all and I don't know if it is even different from what AR does.
    -Im wondering how the algorimte is working. The real color blending is great absolutly! But i was disapoint that red not work.

    I guess the real problem is that the only way to make this accurate is scanning huge amounts of manually painted sheets and then locating the closest matches when simulating mixing... hm, now this is something to think about, as it would let us use real paints to create lookup tables for our favourite real-world paints and use their mixing behaviour in AR ;-)
    ................................

  9. #9
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    Click image for larger version. 

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    No problems.

  10. #10
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    In my experience real color blending would mimic real medium where in oil or acrylic a primary blue with a red make violet. Primary yellow and blue make green and primary yellow and red make orange.
    I think the real world color blending does this in ar 3.
    Especially if you blend them together with a palette knife.
    Even watercolor will blend to achieve these secondary colors with the palette knife.
    I used the first palette knife setting to blend first watercolor then oil then felt pen and last gloop... they all did a pretty amazing job as far as I am concerned at duplicating real medium blending.
    I don't really understand why we are trying to compare it to cmy ink colors.
    In real world artist color you start with red as a primary color....you don't blend to make red. It is a primary color.
    It looks remarkably accurate to me. (click image to view larger)
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    Last edited by screenpainter; 12-17-2009 at 03:10 AM.

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