The maths was right, except it was all being done on colour values than already had the CRTs response curve baked into them. You may have heard of “gamma correction”. Well, this is when you correct an images colour values for the display you’ll view it on.
Blending before gamma correction and after gamma correction produce very different results. The cards were doing it after. This story is about doing it before.
Paul Debevec had similar observations around the same time. His work at the time was all about HDRI and that was put into Source a few years later.
That’s the issue with RGB colour space in general. That’s why when you’re working with anything graphics related (3D modelling, colour grading, etc) your first step is to switch to a different colour space.
For those who just wanna know: cards at the time performed math on brightness values assuming a linear brightness scale when it should be logarithmic.
…ish
The maths was right, except it was all being done on colour values than already had the CRTs response curve baked into them. You may have heard of “gamma correction”. Well, this is when you correct an images colour values for the display you’ll view it on.
Blending before gamma correction and after gamma correction produce very different results. The cards were doing it after. This story is about doing it before.
Paul Debevec had similar observations around the same time. His work at the time was all about HDRI and that was put into Source a few years later.
Figured someone would do it better than me. Thanks for the correction
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That’s the issue with RGB colour space in general. That’s why when you’re working with anything graphics related (3D modelling, colour grading, etc) your first step is to switch to a different colour space.