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Thread: Layer Opacity

  1. #1
    Join Date
    Feb 2007
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    Layer Opacity

    Does anyone understand the layer opacity dial?

    I paint with oils, 50% Thinners on default paper. Add an extra layer.

    I paint black on top layer and white on bottom layer.
    I set opacity dial to 50% - and would expect a 50% gray - but no, the result is a it's a 67% gray.

    Other values black top, white buttom:
    opacity 10% - result 94% gray
    opacity 25% - result 85% gray
    opacity 50% - result 67% gray
    opacity 70% - result 49% gray
    opacity 75% - result 44% gray

    Values from white bottom, black top:
    opacity 10% - result 25% gray
    opacity 25% - result 44% gray
    opacity 50% - result 66% gray
    opacity 70% - result 81% gray
    opacity 75% - result 84% gray

    Have anyone figured out what to expect when using opacity?

    My goal was to use it for colour mixing - but I guess that might not work...

    Using ArtRage 2.2 Full on Win XP with mouse.

    - DoodLS

  2. #2
    Join Date
    Apr 2006
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    I don't have an answer for you, but I have a question!

    What exactly did you mean that wanted to use it for colour mixing? I would think this would be very difficult -- wouldn't you need layers for each color your are trying to mix, and for each area of the painting in which you were mixing colors (e.g. if you had three spots with mixed colors, each mixed from three colors, you would need 9 layers).

    D.

  3. #3
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    Colours are blended with gamma correction so they visually appear more linear. ArtRage isn't intended for use with precise colour blending values - there are other applications more suited to that sort of use.
    AndyRage's mantra for graphics engine code:
    "Sure - how hard can it be?"

  4. #4
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    If you really want precise numeric colour picking, you can use the precise colour picker in ArtRage.

    Single click in the bottom-right corner's current colour swatch to bring up the numeric picker. Then you can precisely enter the colour you want.
    Attached Images Attached Images  
    AndyRage's mantra for graphics engine code:
    "Sure - how hard can it be?"

  5. #5
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    With colour mixing - I mean just that: The art of mixing colours as in real life - without using the numeric colour picker.

    But sometimes it's hard, e.g. when using chalk. I have then used this method with layers previously - but allways thought I would get a 50/50 mix of two colors:
    I would typically want to mix two colors (that I allready have) to get a midtone between the two. E.g. I would paint a red on the lower layer, then add a new layer with 50% opacity and paint a yellow on top of that. That gives me a nice orange which I can then Alt+click pick up and paint along with (together with the two original colours). This way I would be able to do colour fades.

    I have then read some books on colour mixing and mixing paint directly on canvas. Some examples are with painting green leaves. You would start with painting yellow and then paint over with blue to get the resulting green. But in a pc yellow+blue = gray - so that doesn't work.

    It's just a silly idea I know, but i thought it would be nice to try and use ArtRage - painting simulator - as a real painting simulator, and mix the colours I want to use, using only e.g. red/green/blue & white+black oils - to get the resulting colour. I find that the colours I mix are often much better than if I would use the Color Control.

    DoodLS

  6. #6
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    In a future version of ArtRage I'll likely use a different colour mixing model to the one currently in ArtRage. It's a bit old and crusty now. I know I can do better.
    AndyRage's mantra for graphics engine code:
    "Sure - how hard can it be?"

  7. #7
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    Andy - I think it's ok allready. You have done a GREAT job!!!

    Red/Yellow/Blue is the pigment based approach (subtractive).
    Red/Green/Blue is the light based approach (additive).

    Obviously one can argument for both models in a paint-simulator, but since the screen is rgb based anyway, and computers usually are too - I think it is just OK that you have choosen that model.

    I just felt I need to know what to expect, when using canvas based/layer based colour mixing in ArtRage.

    The gamma approach is absolutely OK. I don't have any experience from real world colour mixing at all - but I'll bet ya a 50/50 mix of pure white/pure black (if such a thing exists) probably wouldn't give a 50% gray anyway. I believe real world colour mixing is just a tad more complicated than that - one day I might ask Tinzo...

    DoodLS

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