Re: [png-mng-implement] Problems in PNG display...

[<gl...@co...>]

----- Original Message -----
From: jb...@ac...
To: 'Glenn Randers-Pehrson' <gl...@gm...>
Cc: 'PNG/MNG implementation discussion list' <png...@li...>
Sent: Fri, 24 Jun 2011 21:01:29 -0000 (UTC)
Subject: Re: [png-mng-implement] Problems in PNG display...

From: Glenn Randers-Pehrson [mailto:gl...@gm...] 
>        See http://glennrp.net/png/gamma-composition

Yes, that’s the same result, although *without* any gamma information the actual result depends on the gamma of the screen and this is unlikely to be exactly 2.0 (my numbers were for an encoding of exactly 0.5 – it’s easier to work out that way ;-)

When the PNG is tagged sRGB the correct output values (also in sRGB) are as follows:

(180,255) -> 180
(127,170) -> 183
(0,128)     -> 187

           I revised the reference image accordingly.

           Glenn