color
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Fundamentals How Close Is Your Colour to the Real Thing?
Lesson 5 of The Image as Data. Converting between colour spaces is exact arithmetic; deciding what the numbers mean physically is a fit. Checked against a colorimeter on 22 chart patches: treating the developed file as sRGB lands 9.54 ΔE*ab from the light in the room, the camera's own published matrix does no better, and a 3x3 fitted here and scored on patches it never saw reaches 2.41.
Fundamentals Sensing Colour: The Bayer Mosaic, and What Interpolation Costs
Lesson 5 of Image Sensing. A silicon photosite is colourblind, so a mosaic of filters gives each one a single colour — a quarter red, a quarter blue, half green. Two thirds of every colour image is therefore interpolated, and measured against photosites that actually exist, that guess costs 4.7 DN on a flat patch and 129.9 DN at an edge: twenty-eight times worse where it shows.