True or False (Lighting and colour) (12/25/09 Post #9: New question)

[Alex Chow]

Here I go again...

In this Briggs post, assuming white main light and white ambience/secondary light, brightness is the only aspect that changes while hue and saturation stays the same in the shading series.

(diagram by Briggs)

Taking a look at this picture:



True or false...

The diffuse reflected regions where the presumably white sunlight hits are more desaturated (going towards white) than the shadowed areas only because sunlight is incredibly strong. This makes it a special exception to what Briggs stated in the post. This does not apply to weaker lights, most notably artificial light.

Thanks in advance.

[plundh]

Constant saturation holds true in the real world, but a photograph doesn't show real life perfectly. It lacks the dynamic range to show colors that bright, so it just shows up as white. It has more to do with the exposure of the photo than how light works in life. Basically, your statement is true for photos.

Pigments have the same limitation, so if you were painting this scene from life, you would somehow have to solve this problem to give an illusion of brightness.

[Elwell]

As Zvuv said, those lights are only blown out because of the limitations of photography.

[Alex Chow]

That makes sense. I've always wondered why some artists (digital) paint it the "photograph" way and some with more constant saturations.

Thanks.

[HunterKiller_]

Color theory is only there to help, you're not a slave to it.

If it looks good, it looks good.

[Alex Chow]

Color theory is only there to help, you're not a slave to it.

If it looks good, it looks good.

Better to know colour theory and "break the rules" than "breaking the rules" and not knowing why I did something other than noticing other artists doing it.

[Baron Impossible]

It depends on the material. If the sphere was - bizarrely - made of flesh and skin you could expect enhanced saturation around the terminator, due to subsurface scattering where the light emerges through the skin. Similar to if you shine a torch behind your closed fingers.

[Aaron Death]

I asked exactly the same question. haha

Well, for a start the rule only applies to the underlying diffuse reflection; in various parts of the lit areas this colour will be modified by specular reflections of the light source (the highlight) and of the environment; for strongly coloured objects in most natural lighting situations the effect of these additions will mostly be to locally desaturate the colour. (Another complicating factor is multiple reflection, which can boost the saturation locally both in the shadows and in the lights).

Secondly, there are a couple of good reasons why just picking colours from photos can give the wrong impression of what is actually happening:
1. Colour noise tends to be greater in the darker areas of an image - try sampling from a larger set of pixels or blurring the image to get a more realistic measure of shadow saturation.
2. Any overexposure of the lights will result in artificially low saturation. Once one of the R,G or B components of a colour reaches 255 there is nowhere higher for it to go, and further exposure just adds more of the other two components, resulting in desaturation. Even in an apparently well exposed photograph some individual colours can easily reach this limit and so be "clipped" and artificially desaturated. This is true of any colours in the photo with brightness (B) = 100.

A uniform saturation series is just as series of colours in which the R/G/B ratio stays the same and only the brightness changes. It's hard to argue with the idea that this is basically going to work as a series of image colours representing a surface of one colour reflecting different amounts of light.



Anyway, I'm really glad you like the site. As far as making colour difficult goes, whenever a student tells me I'm doing this I take out my copy of Colour Science by Wyszecki and Styles to show them what some real writing on colour looks like!

[Alex Chow]

I figured it was best to necro my own thread rather than to create a new one.

Does anybody have any pictures which utilizes exposure (artificially desaturating high-end values on the lights) effectively? This could be photographs or artwork, preferably with a figure. I know Anime-styled colouring does this a lot but I'm not so sure I can learn from that...

I've been trying to "break the rules" but I haven't been able to do it without making it look really wrong.

If I find anything, I'll post it here too. That said, Google isn't bringing up useful pictures.

EDIT: Here's something to get started:

[Anid Maro]

Hrm, as far as paintings go you may want to look at the work of artists from around the advent of photography. The first image I thought of was Olympia by Manet, he seemed quite fascinated by the effect of the direct lighting from photography at the time which lent towards very washed out lights.

[PieterV]

Velazquez has similar effects in some of his paintings (or at least his reproductions). Im quite fond of the effect myself, it gives a certain drama. It's basically a strong full-light + higher chroma midtone.
It's not really a photographic effect pur-sang tough.







The last one looks pretty overblown by the camera tough, but the effect is there.

Caravaggio also has pretty heavy chiaroscuro...

[Serpian]

I'm not sure if this is what you meant, but I thought of this post by James Gurney:

http://gurneyjourney.blogspot.com/20...and-glare.html

I will try to refrain from saying that this link might shed a little light on the problem.

[Alex Chow]

I'm not sure if this is what you meant, but I thought of this post by James Gurney:

http://gurneyjourney.blogspot.com/20...and-glare.html

I will try to refrain from saying that this link might shed a little light on the problem.

That's actually what I meant. In fact, I didn't know the eye temporarily creates this effect in strong sunlight. I thought only photographs would show the glare. Thanks!

I'll check out Manet. Good call.

As some people have stated in my Ambient Light thread, though, it's hard to tell if Velasquez intended the colours to be that way because these are reproductions. Maybe he did... maybe he didn't but I'm not so sure if I want to refer to those (for purposes of this topic) because it may not have been Velasquez's intentions (of course, if anybody has any info to shed light on this, I'll be happy to read it). Thanks for the recommendation, though. He's an awesome artist regardless. Caravaggio as well, though I think he's a safer bet since he's just a madman for contrast.

[dpaint]

Zorn uses this lighting situation all the time. I think impresionist painters use it more because they are trying to get that sense of light and they use the shadows and reflected light as the focus and let the lights go allot of time.