I've got a few questions about color luminence / perceived brightness (or whatever you want to call it - the attribute that encounters that we percieve yellow hue brighter than blue for example)
Firstly, is there a tool / program / color sistem that enables you to get colors of the same luminance?
Say I pick a color - determine RGB values - and the program gives me all the colors around the color wheel with the same luminance but different hues?
And secondly, which algorithm is used to determine color luminence on this website:
It looks like, they used none of the following algorithms usually used to calculate luminance:
(0.2126*R) + (0.7152*G) + (0.0722*B)
(0.299*R + 0.587*G + 0.114*B)
sqrt( 0.241*R^2 + 0.691*G^2 + 0.068*B^2 )
I assume that you're looking for selecting colors with the same L from HSL color mode (hue-saturation-luminance). You can find this in photoshop after selecting colors with eyedropper, and viewing color picker, but this is manual and tedious work. I don't know any tool or function in photoshop that selects color based on luminance channel. I don't think that such tool exist anyway in any photo editing software.
Or - you can try magic wand tool with tolerance set to 1 and allow it to select all pixels with that lightness on layer. This should work somehow...