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Seeking Online Additive Color Calculator

CurtisOliver

CurtisOliver

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Wish I knew how to do that. :)

Edit: Recalculated using guassian profile and 1nm+/- FWHM

Alaskan2.png


Still very green heavy.
 
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Radim

Radim

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I inspired myself from code I found in Java (if I'm not mistaken) on web. I have it in VBA and Excel. Too messy to publish... Basically you need to calculate rgb values for wavelength, convert it in hexadecimal and color stuff. I have also very simple function for aditive color mixing of rgb channels - works well. I'm thinking about using it in spreadsheed for various laser calculations once.
 
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CurtisOliver

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I had all this in excel. The real problem comes down to the balancing when combining wavelengths together. Also a lot of calculators are photopic biased. So blue and red are often wrong.
 
Radim

Radim

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CurtisOliver said:
I had all this in excel. The real problem comes down to the balancing when combining wavelengths together. Also a lot of calculators are photopic biased. So blue and red are often wrong.
Click to expand...

You can adjust gamma function accordingly when calculating rgb of given wavelength you are composing the color combination off. Just give it some intensity/weight according to power. I use weighted average for rgb to fit 0 to 255 for each channel. Of course the gamma function respect some distribution which you can adjust according to light conditions (dark/daylight). I need to write it with more precision when I get back to it.
 
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CurtisOliver

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If you do manage it, please share it with us. I would love to test it out.
 
Radim

Radim

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Yes, why not... But it is not on the schedule nearby... I also have those photopic and stocopic luminosity functions values by 0.1 nm (I used them for flashblindess and distraction hazard distances calculations and some other calculations), from here I might get quite precise gamma function to represent the wavelength's rgb values. (I use very simplified one in current calculator - see how messy it is? :D) I downloaded these function values also from web.
 
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CurtisOliver

CurtisOliver

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Very nice. I also took down all the scotopic and photopic data, I then inferred mesopic from the two sets of data. It was only rough however.
 
Radim

Radim

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Yes, you can combine them with some weights to get something between. When thinking about that it would be usefull to add sliders there to simulate some transition between day-night conditions sunrise/sunset times... I need to study human eye adaptation processes to get more complex solution.
 
paul1598419

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Thanks for that explanation. I was unaware of a gamma function used in photography. I was a bit confused by the weighted values for differing daylight/night time backgrounds. I will look into this in more depth at a later time.
 
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