[Tig] Influence of gamma on image resize

Simon Burley simon at rpsfilmimaging.co.uk
Wed Feb 24 21:15:14 GMT 2010


On Wed, February 24, 2010 3:43 pm, Bob Friesenhahn wrote:

> The article at
>
>    http://www.4p8.com/eric.brasseur/gamma.html
>
> provides a facinating description of why resizing in linear-light can
> be important in order to achieve a correct result.  GraphicsMagick
> does not do this by default, but explicit gamma correction steps
> "cure" the problem:
>
>    gm convert gamma_dalai_lama_gray.jpg -gamma 0.45 -resize 50% -gamma 2.2
> resized.jpg
>
> Thoughts?

Most commercial (and also open source) applications don't make any
provision to bandlimit the source image if reducing it's size, and hence
introduce aliasing, which is evident on the pictures on that site.

-- 
Simon Burley
RPS Film Imaging Ltd
** Please note new telephone number below **
T: +44 (0) 208 661 9900
M: +44 (0) 7702 732 655
e: simon at rpsfilmimaging.co.uk



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