[iyonix-support] Re: Graphic cards and noise - warning
- From: "David J. Ruck" <druck@xxxxxxxxxxxx>
- To: iyonix-support@xxxxxxxxxxxxx
- Date: Sun, 22 Oct 2006 12:46:16 +0100
On 22 Oct 2006 David Pitt <pittdj@xxxxxxxxxxxxxxx> wrote:
> In 32K colours red and blue are transposed. 16M and 256 are OK.
Unlike earlier cards supplied with the Iyonix, which had the red and blue VGA
output channels physically swapped over, the new cards are supplied
unmodified and the colour transposition is done in software for 256 colour
and 16M colour modes. However, 32K modes are not swapped by RISC OS 5.12.
Geminus (once updated for 5.12) should also be able to correct 32K modes, but
with a possible performance penalty.
The advantage of using the cards as standard should be more acceleration
features can be utilised, particularly those which involve colour weightings
which will not give the correct results with phyisically swapped channels.
The loss of 32K colours should not be much of a problem as it was only ever a
stopgap when graphics cards had limited memory and bandwidth and could not
manage full resolution at a higher colour depth. Now cards can do all modes
in 16M modes with no performance penalty, and indeed software is often faster
in 16M as it does not need to preform dithering used in 32K or less.
About the only exception to this is VNC clients/servers which may transmit
twice as much data across a slow network if one or the other end is in 16M,
in which case it is better to manually configure 8bit colour depth for
maximum performance.
Cheers
---Dave
--
____________________________________________________________________________
David J. Ruck Phone: +44- (0)7974 108301 Email: druck@xxxxxxxxxxxx
____________________________________________________________________________
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