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  1. #1
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    Saturation colour theory help

    Wondering if anyone can help. I've been painting digitally for a while now, but still learning. And was trying to show a friend some stuff, but got stuck on this question.

    Often i paint desaturated shadows and more saturated highlights and i've found a lot of digital paintings use this. But why? Or even am i wrong?

    In terms of realistic painting theory, are highlights always more saturated that the shadows or can you have desaturated highlights and saturated shadows?

    I assume the saturation comes because the saturation of the lights colour adds on to the saturation of the local colour of the object. And also what happens if the colour of the light is the compliment of the local colour of the object its illuminating, does that cancel out the saturation?

    Sorry saturation confuses me, what do you guys do for it? Any rules of thumb or anyone know of any good articles that explain this?

    Any thoughts

    Thanks very much

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  3. #2
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    shadows are usually desaturated. Think about it, not alot of light gets in there and what does is getting reflected off other surfaces so it loses some wavelengths of color before it hits the shadow area.

    Highlights are actually typically less saturated then the light area. This is because when highlights occur they act more like a mirror then just bouncing a few wavelengths of light. So they are more white then any other color.
    a highlight can be desaturated if the thing it is a part of is desaturated. for example a highlight on a brown item, pure brown is a pure desaturated color as far as pigments are concerned.

    If the light color is the compliment of the item it is illuminating it will desaturate it.

    i would recommend reading Johannas Ittens "The Art of Color"
    also i would suggest a physics text book on light. Understanding how light works will be imensly helpful.

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  5. #3
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    Prom has some excellent insights in parts of his tutorial.

    http://itchstudios.com/psg/art_tut.htm

    "The proper rewards are not simply tacked on to the activity for which they are given, but are the activity itself in consummation." -C.S. Lewis
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  6. #4
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    Ah thanks very much. That helps a lot.

    Is it also true then that a midtone, not a highlight but a brighter diffuse on an object would be more saturated?

    Thanks for the hints i will check out the site and have a look at the book. Really appreciate it.

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  8. #6
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    Wow thanks Briggsy. Thats a really useful read

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  9. #7
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    Been thinking about this some more, how would the shading series go if a blue ball was illumated by a yellow light

    So the highlight would be yellow. For the diffuse reflection would the shading series go through cyan - green - green/yellow - yellow, because the light mixes with the local blue colour and goes through all the shades to yellow.

    Edit > >

    No sorry course it goes to white cos the two are complimentary. What i guess i'm asking is when one coloured light illuminates another different coloured object does the shading series become all the shades between the two colours on the colour wheel?
    cheers

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  10. #8
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    ps hey sweetoblivion31,

    this is the book yeah? I found a cheaper cut down version of it in black but i think this is the original.

    Pricey tho, waterstones are charging 70 quid but amazons sellers have it half price : )

    http://www.amazon.co.uk/Art-Color-Su...655772&sr=1-17

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  11. #9
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    yea thats the book.
    there is a smaller version with a black cover. From looking through them the difference seems to be that the big one has a ton of examples using master paintings and the small one doesn't.

    As far as the ball it all depends. What is the ball made of is a huge thing. What is the value of the ball. is it a pure yellow light and a pure blue ball? cause according to physics a pure yellow light shined on a pure blue ball with just make it black cause there is no blue light to reflect back to your eye.

    the best way to do it is to get a lamp a few colored objects (like legos or something thats one color) and a few colored photographers filters and just play around and see what happens.

    theoretically it goes like this (none shiney surface). light side = local + color of light. shadow side = local + compliment of color of light. Cast shadow = local color (but this time of the object the cast shadow is on) + compliment of colro of light.
    so the blue ball would be blue green or green or yellow green (depending on the strength of the light and the color blue) on the light side and blue violet in the shadow side.

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  12. #10
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    Thanks for that sweetoblivion314

    i might go for the larger book as its not so pricey on amazon. And really appreciate the explanation, helps alot.

    The only thing i'm still confused about is why does the shadow side get the local colour and the compliment of the light source. As far as i've understood it the shadow colour is the local colour + background environment ambience but depends on the environment not the colour of the light right?

    Sorry just trying to clear it up in my head, its all very usefull stuff

    thanks

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  13. #11
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    honestly i don't know the physics behind why the compliment thing happens. It just does. If you experiment with blocks it gets cool cause with a white table if you put up an orange filter the cast shadows on the table are this dark blue color. But thats with a single light source and little ambient or reflected light. Ambient light will always affect your colors too, but it will just add to that compliment thing.

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  14. #12
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    Fair enough, i will give it a go. I wonder maybe its a psychological thing. I've heard that warm light will make shadows look cool and vice versa, because your eyes overcompensate for the colour.

    Cheers for that

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  15. #13
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    Sweetoblivion is pretty much right about the colour of the yellow sphere in blue light. The colour you get depends on what is in common between the wavelengths in the light source and the wavelengths reflected by the ball. I think that it would be possible to make a sphere that essentially reflected only "blue" wavelengths (so to speak), but it would be a very dark sphere (e.g. painted in pthalo blue without any white); most actual blue surfaces reflect a range of wavelengths peaking in the blue region, but extending at lower levels through most or all of the rest of the spectrum. In a monochromatic yellow light (e.g.a sodium lamp) a blue sphere would therefore look either black or yellow (like everything else). A yellow light made with a filter on the other hand would probably contain high levels of red, orange, yellow and green wavelengths, and low levels of blue and violet, and would tend to have some dominantly green wavelengths in common with most blue surfaces.

    Note that since the resultant colour is the product of the colour balance of the light source and the reflectance of the ball, it would probably not change much until the very edge of the lit area, unless the ambient/secondary light closely challenged the main light in strength.

    The appearance of the complimentary colour of the light source in the shadow regions is a special case of simultaneous contrast - i.e our perception of colour being influenced by the surroundings. For a detailed explanantion see here:
    http://www.webvision.med.utah.edu/Co...#37;20Contrast

    I think that the effect on the sphere in the shadow would be more to make the blue more saturated rather than to shift it to violet, since blue rather than violet is the complement of yellow when we are dealing with questions involving light stimulus rather than mixing paint.

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