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Video: Light and Color

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Your Text: Insert Slimies » Insert UBB Code » Close Last Tag \| All Tags UBB Help	Man, stuff makes my brain hurt. I get locked onto an idea and my brain runs itself into the ground. ---- A long time ago I was playing with making nebula. Pretty cheesie junk, really. Clouds, Difference Clouds, and colourizing. Standard and boring. But the part that I was interested in was creating several nebula with various hues and putting them together. How do you put a yellow nebula together with a red nebula? And maybe mix in a low magenta nebula? Since light is additive, I just added them together. Yellow nebula with a black ground on one layer, red nebula with a black ground on another layer, and then Linear Dodge. Tada. Nice shades of orange where they over-lapped. ---- In coding, a great trick is to use a look-up table. It's great to calculate parametrics on the fly, but a look-up table can come in damn handy when it comes to speed. An example of this would be gamma. Don't bother doing gamma on each individual value. Rather, build the gamma table and then fly through the data. ---- I've been doing research into the physics of light. Not exactly how they travel, but rather colours and how they interact with surfaces. Nanometer stuff. When it comes to what I'm up to, RGB doesn't cut it. Currently, neither does Lab (but I'm working on hacking Lab for what I want). Converting a wavelength to colour is pretty easy. This is the wavelength and this is the RGB for said wavelength. But I have been fighting and fighting with putting various wavelength together. (One of the big mistakes that I have been making is trying to correlate spectrum and Cie XYZ in ways that they don't correlate. Shame on me!) If you look at a spectrogram of a light source, you will see spikes and all that stuff all over the place. How do you put all of those spikes together for a final RGB value? How does brightness come into play? ---- A long time ago, I was playing with rastor look-up tables. This led to 2D Remap. It also led to a couple of other things, but I left them behind for various reasons. ---- So I was browsing for nanometer and RGB algorithms. Came across some code that uses a look-up table for nanometer > RGB. Sure, no big deal. Expected. But down at the bottom of the code, there was this tiny little and inconspicious loop. What did it do? Turns out that it runs through the data set and [i]adds up RGB values for each nanometer > RGB[/i]. O M G Was it really that easy? Created a rastor nanmeter look-up table, threw a bunch of wavelengths into it, and added them up. Looks like it works. Pffft. Been absolutely wracking my brain over the simpliest and elegantiest of operations: addition. After all, the mantra is [i]light is additive[/i]. So I can create light sources using nanometer data sets. Now I just gotta throw in some surfaces with nanometer reflection data sets and see what pops out. ---- I think the light and surface interaction is going to prove interesting and frustrating. Consider a fleshtone. Largely some shade between red and yellow, so orange of some kind. But what nanometers do you add up to get such a fleshtone? Ugh. Not to mention that it may not be a straight-up nanometer right in the orange range. What if you created the orange shade by literally adding red and yellow nanometers? What about a hint of yellow, a hint of green, and lots of red? How would that interact with a nanometer light source? ---- Typing out some of the stuff in my brain has helped ease the pain. Loading...
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