nanogui: Jpeg images and dithering
Subject:
Jpeg images and dithering
From:
tj ####@####.####
Date:
28 Oct 2005 21:42:32 +0100
Message-Id: <43628D8F.2010409@comcast.net>
I have a question and I do not know if is a nanox or a libjpeg question,
but I'll start here :-) .
I am using nano-x on a 220x176 color lcd with MWPF_TRUECOLOR565 frame
buffer configuration. The problem is graphics are being dithered. In
looking at the problem I have one really big question. None of the RGB
values can be a full 8 (255 decimal) bits, red is 5, green is 6 and blue
is 5 maximum bits respectivly. So, how does either nano-x or libjpeg,
which ever one does it, get them to the 565 format correctly?
In my welcome screen I have large area that is GR_RGB(255, 168, 167), in
nano-x'ese, with all RGB values larger than the 565 limit. On the screen
it pretty much matches the pc screen color, but it is dithered with
white, and maybe other colors.
So, my real question is can somebody tell me how colors larger then the
565 pattern are "mapped" to the actual colors as seen on the screen. And
where that transformation takes place, in nano-x or libjpeg.
Thanks,
tj
