Using GIMP without losing colour depth [LWN.net]

Using GIMP without losing colour depth

Posted Apr 18, 2012 5:00 UTC (Wed) by rgmoore (subscriber, #75)
In reply to: Using GIMP without losing colour depth by PaulWay
Parent article: Natterer: Goat Invasion in GIMP

I've never heard of 24 bits per channel, but 16 bits per channel is what most photographers would like to use these days, and 32 bit floating point per channel seems to be common for HDR images. While 8 bits per channel with a gamma curve may be fine for display purposes, it's not good enough for editing. Applying a strong contrast correction to 8 bit per channel data will result in really ugly posterization or (if you try to correct for it) obvious dithering. You want more bits of color depth than your capture device can provide so any round-off errors will be of noise rather than signal.

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Floating point

Posted Apr 18, 2012 9:23 UTC (Wed) by tialaramex (subscriber, #21167) [Link]

In the audio chain we see 24-bit recordings (for headroom) processed in 32-bit single precision floating point and then mixed down to 16-bit for publication (e.g. CDs)

The rough equivalent in video / photography would be 16-bit raw images (again for headroom) processed to 16-bit half precision floating point (almost the same precision as 12-bit integer but far larger range) with 8-bit published image data. However although GPUs often accelerated halfs, most CPUs do not so far as I know, and so GIMP's native operations would be hamstrung on most computers if it used half precision as its internal representation. That might argue for using 32-bit floats even though they're probably overkill.