## Mandem's recent activity

• One last question: Could anyone please show me what a 3D technical conversion LUT from a larger colorspace to a smaller color space(Like Rec709) look like in terms of an RGB lattice? I've been ...
• This is EXACTLY the answer I was looking for. I had read multiple times online that to transform from one space to another a conversion matrix has to be applied to a linearised projection and was ...
• Sorry, but what are the coordinates you are using for your rec 2020 primaries? I am only familia with the ones in the image below
• Replied in Mapping
Pardon my ignorance, but what exactly does a colorimetric match mean?
• I'm trying to understand what the term "interpret" means here. Are you saying if I had a rec2020 and a rec709 screen right next to each other the (810,236,75) rec2020 would produce the same color ...
• This is exactly the conclusion I've come to.
• I'll try my best to explain it from my pov. Bear with me. If both the Max Diffuse White, Clouds and the Mirror are lighted by the same light source, say the sun, which is providing an X amount of ...
• The common explanation(and, perhaps, overly simplified) online is that 3D and 1D LUT's simply give a certain RGB output for a given RGB input. This explanation doesn't seem to explain how then ...
• I'm not a practitioner. Just someone who is genuinely interested. But yes, I have grasped the concept of Diffuse, Specular, and Mixed. If you look at my example above with the camera out in a ...
• Quite the contrary. After our discussion, I am fully convinced the "reflectance" values on Lutcalc are indeed luminance values. The idea of an 18% or 90% is in reference to the luminance of an 18% ...
• But using the above 3 formulas we can never get a value higher than 1(100%) for reflectance. Or are you saying calculate the Reflectance value for the diffuse reflective 100% paper and the ...
• So i'm guessing it is indeed "sloppy terminology" and a misnomer when they say "reflectance" . That would make sense as the formula for Reflectance=Reflected Light /Incident Light just doesn't ...
• If exposure and metering theory assumes uniform light throughout the scene then the only thing I can understand causing more than a 100% reflectance is like you said previously the conversion of ...
• Replied in 100% of what?
Does this not mean that there is some standard against which it is being measured? Perhaps the average illuminance of the scene? Say we have 2 areas in a frame, one significantly more illuminated ...
• So when we look at the graph where we start dealing with above 100% reflectance, is that just specular reflectance getting translated into it's equivalent in terms of diffuse reflectance. Which, ...
• Replied in Fluorescence
Interesting. So what about the claimed 90% reflectance for white paper? Also, why use optical brighteners to begin with? It's just that it's so unintuitive having reflectance percentages greater ...
• Good point. Flew over my head for some reason. But how do you translate incident light sources into a reflectance %. And would this also mean anything above 100% reflectance is by definition an ...
• I was looking at the curve of SLOG3 but didn't understand how light can be reflected more than a 100%? This indicates to me that 100% reflectance isn't really 100% and that instead it's in ...
• Thanks for taking the time to answer. I am not too familiar with how Floating Point Operations actually work but I understood the gist of it in that they allow almost an infinite amount of values ...
• My question is more from a Video/Color standpoint but since video is based on the principles of photography I figured perhaps someone could help(I've asked on the video forums as well) To explain ...
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