CLUT QUESTION

1
I have just installed a 10 bit card into my mac and am fixing the
clut. I am using the LoadClut command, but under the 'startentry'
field, i am unsure what to use. When i use 1 as the startentry,
my clut matches up and i get the expected results. However,
when the default of 0 is used, everything is off by 1. I am
wondering where this 0th position leads to in the machine,
because no matter how i change it, i dont see any change in the
images on the screen.

thanx
`shri
2
Hi shri,

what loadclut does, as far as I know, is putting the clut you defined
(indexed 1 to 256)in the hardware clut of your machine which is
indexed from 0 to 255. A difference of 1 between the clut index and
the hardware clut index. I took this from the info on the LoadClut
command:

"startEntry" is optional and determines which hardware CLUT entry to
load first (entries are numbered from 0 up). The default is 0. The
first element of clut, i.e. clut(1), will be loaded into hardware
entry "startEntry".

So I suspect that when you use startentry 1, all hardware clut
indices get shifted by 1 and the indices for both hardware clut and
your own defined clut will be the same. So I guess your problem is
just an indexing problem.

best regards
Jeroen Benjamins



--- In psychtoolbox@yahoogroups.com, "snp2006x" <snp2006@c...> wrote:
> I have just installed a 10 bit card into my mac and am fixing the
> clut. I am using the LoadClut command, but under the 'startentry'
> field, i am unsure what to use. When i use 1 as the startentry,
> my clut matches up and i get the expected results. However,
> when the default of 0 is used, everything is off by 1. I am
> wondering where this 0th position leads to in the machine,
> because no matter how i change it, i dont see any change in the
> images on the screen.
>
> thanx
> `shri