Re: Images on /CD/
Hi Peter,
On Fri, Jan 04, 2002 at 08:58:35PM +0100, peter karlsson wrote:
> The colours on the navigation images on /CD/ do not match the
> background colour for the bar, which makes the bar look quite bad...
> Is the gamma correction set incorrectly for the PNG images?
I made those images. They do not contain any gamma chunk, so they
ought to be displayed with a linear mapping. The palette entry used
for the background is #e09e86, which is also what the web page uses.
> Please see http://www.softwolves.pp.se/privat/20020104_debian_CD.png
> for an illustration.
The same thing happens on Netscape 4. Mozilla and Konqueror display
the page correctly. Do you use a 15bpp screen mode? I do, and I
suspect that some browsers round the RGB values incorrectly.
The problem may also be due to the fact that some browsers (Mozilla
and Konqueror among them, I think) first render to a bitmap internally
and then paste the whole bitmap to the screen in one go. Others, like
NS4, draw rectangles, text etc. directly onto the screen. In this
case, some rounding introduced by X may spoil things.
Maybe it would be wise to use a colour with only 15 significant bits,
e.g. instead of #e09e86 use #e0a088 (second hex digit always 0 or 8).
> See http://www.libpng.org/pub/png/pngapbr.html for more info on PNG
> handling in browsers, especially in conjunction with web specified
> colours. http://pmt.sourceforge.net/gamma_test/ is an interesting
> test for the gamma.
Thanks for the pointers - interesting!
Cheers,
Richard
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