Re: [GM-help] Linear Colorspace

[Bob F. <bfr...@si...>]

On Thu, 3 Dec 2015, Sam Wilson wrote:
>
> Good enough for me for now. On a technical level, isn't this an
> approximation since sRGB doesn't have a constant gamma?

Yes.  However, sRGB is a statistical average (based on CRT monitors 
from the early '90s) and might not actually represent the images you 
have.  Were your images adjusted on CRT monitors calibrated to the 
sRGB standard?

>> "Empirical evidence suggests that distances in color spaces such as
>> YUV or YIQ correspond to perceptual color differences more closely
>> than do distances in RGB space.  These color spaces may give better
>> results when color reducing an image."
>>
>> The same issues apply to resize and any other operations which blend
>> pixels.
> Are you suggesting that resizing in YUV or YIQ would yield better (or at
> least) the same results?

Theoretically.  CIE LAB colorspace is known to be very good at 
perceptual uniformity (but GraphicsMagick does not currently support 
CIE LAB). YUV is just about as good.  Colorspace conversion might add 
errors due to the math involved.

RGB is a pretty good space for image processing.

Bob
-- 
Bob Friesenhahn
bfr...@si..., http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/