I noticed that when a plane is positioned away from the light source, not only does the value decrease, but the saturation does too.
Not only that, when the value decreases, the saturation must decrease from what I understand.
A lot of planes positioned in core shadow have a low saturation grey'ish tint to them.
Does this seem right to you?
Should I see them as two distinct entities, because our eye perceives value and saturation in different cells no, is their only relationship the light hitting them? Or is it good to notice the relationship?
I know there's a lot of books on colour theory, discussing the relationship of hues and how they relate....but is there a book which anyone would recommend, which maybe also has a good explanation of saturation and values and their relationship to light and each other? It's mostly for picking the right colours for each plane.
Last edited by Kaycy is tanning; October 10th, 2009 at 10:47 PM.
Sometimes, but not always. I mean for example I've seen illustrations with rather saturated shadows, however the chroma is affected.
This http://www.anderszorn.org/Eldsken.html has rather saturated shadows. The skin tones are lighter in value.
I know there's the old joke, color is relative but it is. If you study impressionist paintings they weren't tonalists. (Though some came from that background)
You can try looking for Creative Illustration by Andrew Loomis. Most of what I was actually learning from was from Jason Manley's lecture on Color theory (besides other books). That and I looked at Briggsy's http://www.huevaluechroma.com site.
Last edited by Arshes Nei; October 11th, 2009 at 07:44 AM.
Thanks, that's very chromatic (edit from saturation) and still it has a core shadow. The light itself there seems to have a yellow hue too. I'm going to check out that book and site, thank you.
Last edited by Kaycy is tanning; October 11th, 2009 at 12:52 AM.
Yea, Arshes Nei is right, and this doesn't relate only to paintings, but also studying life.
I too noticed variations in saturation, but you can't make up a formula, or at least I can't yet. There are times when planes in different light have the same saturation or palnes that have the same light have different saturation, or think about the planes in the light that tint towards the color of the lightsource. There's a lot going on in there.
I guess, at some point you will notice some 'patterns' and will expect some things to happen, and most of the times they will. Experience will give us this.
"Don't judge a book by it's cover" Frank Frazetta 1928-2010
DA gallery http://michaelsyrigos.deviantart.com/gallery/
CA Sketchbook http://www.conceptart.org/forums/sho...d.php?t=131601
Nod, there's a lot more going on. I'm reading "computer graphics-Foley" and learned that the angle of the plane does not always determine value either.
Something called Lambertian reflection http://en.wikipedia.org/wiki/Lambertian_reflectance where the angle at which the light is hitting the plane =/= it's value. Examples are chalk, wood, etc, rough surfaces which cause diffuse reflections. Moving around the object will not dramatically change it's value apparently, since the surface being rough (chalk, wood) causes the light being scattered instead of directly reflected.
I did know this from real-life, I know matte surfaces will look a lot different, I just never read about the reasons up till now.
Last edited by Kaycy is tanning; October 10th, 2009 at 11:37 PM.
Kaycy, it's because of Lambertian reflection that value does relate to the angle of the plane. Each point on the subject looks the same value from any angle of viewing, but that value drops as the surface turns away from light, because progressively less light energy hits the surface per unit area. Lambertian reflection applies (approximately) to dull surfaces and to the body (or "diffuse") reflection of polished opaque surfaces.
On your original question the pages beginning with this one might be helpful, but I need to add a lot more:
Yes, you're absolutely right, I reread that chapter. (16.1.2 Diffuse reflection). It's actually the viewing angle that doesn't matter, but the angle to the light does, like you say.
This is part of the simplified model they use:
"Dull, matte surfaces, such as chalk, exhibit diffuse reflection, also known as Lambertian reflection. These surfaces appear equally bright from all viewing angles because they reflect light at equal intesity in all directions. For a given surface, the brightness depends only on the angle ° between the direction L to the light source and the surface normal N."
edit: Now that I think about it, this seems to be the basic model for simple modeling I've been using to model something (dull surfaces as you mention), disregarding the viewing angle for lighting, but only for composition (unless I use spectral highlights).
BTW, I really enjoy reading your site, I was particularly interested in the cosine equation where the plane ° to the lightsource does not go up and down linearly with the value but the value stays quite high at 0-60° and then quickly descends (cosine) towards perpendicular stance. It's described in the book and I can relate tot that in RL, and see it.
My original questions seems answered more or less for me thanks to your article. I thought the chroma would change, but chroma and saturation stay similar becaus the light saturation nor the surface material changes under inclination of planes, but the value (energy) on a 'per pixel basis' does (cosine equation) (I hope I got that right).
I (hope) I got at least half of those things correct. It really doe shelp studying this when I need to pick colours, I was guessing more or less at first and eyeballing it, now my colours are a bit closer to RL (painter 11). I watched some videos of someone painting in painter who had no issues picking the right colours for his concepts, his skin tones and chroma were spot on each time, painter doesn't have the visual value balance 'bar' photoshop uses, hopefully I get better at this by understanding light.
Last edited by Kaycy is tanning; October 11th, 2009 at 06:05 AM.
It's a very informative exercise, when working from life, to view your subject from several different angles and see how the values and chroma change, even though the lighting is the same.
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