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Discussions of photographic materials usually use density instead of opacity. Density is a logarithmic value equal to -log10(transmission), where transmission i
by abram 5y ago
Discussions of photographic materials usually use density instead of opacity. Density is a logarithmic value equal to -log10(transmission), where transmission is the amount of light passed through (or reflected) on a scale of 0 to 1.
So to give some examples, a material with 100% transmission would have a density of 0, a material with 10% transmission would have a density of 1.0, and a material with 1% transmission would have a density of 2.0.
Density values have some advantages, including:
- They can be combined with simple addition
- Compared to transmission or opacity values, they correspond more closely to human visual perception
- magicalhippo 5y agoThis is more generally called absorbance[1] and stems from the Beer-Lambert law[2]. Been too long since I've done computer graphics, but you made me think about implementing transparency pass using absorbance instead. [1]: https://en.wikipedia.org/wiki/Absorbance#Absorbance_of_a_material https://en.wikipedia.org/wiki/Absorbance#Absorbance_of_a_mat... [2]: https://en.wikipedia.org/wiki/Transmittance#Beer%E2%80%93Lambert_law https://en.wikipedia.org/wiki/Transmittance#Beer%E2%80%93Lam...