Re: 24-bit-per-pixel limit to Gdk RGB ?
- From: individual <individual mi cl>
- To: gtk-app-devel-list gnome org
- Subject: Re: 24-bit-per-pixel limit to Gdk RGB ?
- Date: Tue, 18 Feb 2003 12:08:01 -0300
On Tuesday, February 18, 2003, at 06:49 AM, Peter Finderup Lund wrote:
On Tue, 18 Feb 2003, individual wrote:
Is there a way to display 48-bit-per-pixel image data? The API
reference entry for GdkRgbDither states:
"Since GdkRGB currently only handles images with 8 bits per component,
dithering on 24 bit per pixel displays is a moot point. "
Shift the pixel data each channel by 16 bits before you stuff them in.
It's very difficult to see the difference anyway and most X servers
won't
be able to give you a visual(*) with more than 8 bits per channel
anyway.
Definitely not XFree86. There are a few consumer grade cards out there
which will give you 10 bits per channel (or, I think, 10 bits for the
green channel and 8 for the others) but driver support for that is
probably scant.
Wait... we must be misunderstanding each other. Last night I realised
that for Gtk to be limited to 8-bit colour is absolutely ludicrous! Gtk
is the Gimp Toolkit, and the Gimp is for hight quality images!
But, on the other hand, I must admit I am a bit confused by this issue.
As I understand it, 8 bits per channel will give me 256 levels of
colour for each colour. If I were to make a gradient of red, for
example, in The Gimp, I would expect to see bands of colour in a
red-to-black gradient that is as wide as my monitor (about 1000
pixels), which should make each band about 4 pixels wide. I tried it
and... er... no bands visible.
Ok then, let's try it with a 1000 pixel wide gradient, but going from
255 red to 128 red. No bands. Hmm....
Ok, last attempt: I made a 1000 pixel wide gradient going from 255 red
to 254 red. In the colour selection panel, I can clearly see the
difference between the two colours. When I draw the gradient, there is
no dividing line. HA! I have therefore proved that The Gimp and my X
server are capable of displaying colour at more than 8 bits per
channel. Or have I?
Thanks for putting up with these questions!
Paul
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