Computational and Biological Vision“Colors Out Of Space”Digital color representation, color spaces and more!

Amir Eluk

Software Engineering

Introduction

0Representation0Color Model0Color Space0Gamut0Color Blending Modes

sRGB

0Additive Color Mixing0Easy to generate physically0Standard for most devices0Poor gamut0Unintuitive0Biologically? (cones response)

Color Gamut

sRGB Adobe RGB Adobe Wide Gamut ProPhoto RGB

CMYK

0Subtractive Color Mixing0What is K for?0Used by printed media

HSV/HSL

0More intuitive0Easier to pick colors0Not perceptually uniform

L.a.b

0Easy to pick colors0Can be perceptually uniform0Replicate opposite color theory

L.a.b

L a B

(Dichromat types?)

Perceived Brightness level

Histogram Comparison

RGB Lightness (Lab)

Close but not equal, why?

Histogram Comparison

Green (RGB) Lightness (Lab)

A coincidence ?

Image Bank &

(table of mean absolute difference)

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similarity

Lightness & Green: 2.1

Lightness & RGB: 2.5

Lightness & RGB: 27.5

Lightness & Green == Lightness and RGB: 8.4Lightness and Blue: 24.6

Conclusions

0The brightness of an RGB image is composed of its three channels with most weight given to the Green channel, Red comes second followed by blue.

0This uneven contribution to the brightness is the reason why simple average of RGB values is not the exact brightness of the image.

Questions

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