10-04-2018, 10:07 PM
The formats you export to (GIF, JPEG, PNG) are all gamma-corrected (perceptual). if you are in linear light, this conversion is added for export.
In 8-bit, round-off errors creep in quickly. Experiment, try this;
1) Create a 2560x400 image in 32FP mode.
2) Draw a black to white gradient across it
3) duplicate the layer, and set to "Multiply" mode.
The gradient will remain smooth.
Repeat 1-3 but with a 8-bit image, the final result has visible banding (more visible around the center). This is because in 8 bit your gradient has 256 10px steps. The steps are not very visible because their values are very close to each other. But when you multiply, the values are much more different. In more than 8-bit every pixel will have a different value from its horizontal neighbors and you will have 10 intermediate values.
In 8-bit, round-off errors creep in quickly. Experiment, try this;
1) Create a 2560x400 image in 32FP mode.
2) Draw a black to white gradient across it
3) duplicate the layer, and set to "Multiply" mode.
The gradient will remain smooth.
Repeat 1-3 but with a 8-bit image, the final result has visible banding (more visible around the center). This is because in 8 bit your gradient has 256 10px steps. The steps are not very visible because their values are very close to each other. But when you multiply, the values are much more different. In more than 8-bit every pixel will have a different value from its horizontal neighbors and you will have 10 intermediate values.