imshow/image colormap problems in 3.0.1

[Michael G. Ross]

I'm using the Octave-Forge packages for Octave 3.0.1 and Gnuplot 4.2.3  
on Mac OS X 10.5.2

I read a truecolor PNG image in with imread, and if I display it using  
image or imshow it appears in Gnuplot but the colormap is off -  
everything is very white as if very small RGB values are being treated  
as the maxes. However if I display it with imagesc it appears fine.

If I specify imagesc(img, [0 255]) I also seem to get the correct  
scaling (reducing image brightness reduces its display brightness in  
Gnuplot).

The main difference appears to be that imagesc(img) calls
set(ret, 'cdatamapping', 'scaled'), which puts the colors back in the  
displayable range. Specifying the scale ranges calls set(ax, 'clim',  
[0 255]).

According to the Matlab docs, the cdatamapping property should not  
affect a truecolor image, so image/imshow should not have to set these  
properties - but something appears to be going wrong.

----
Michael Ross
mgross at mit.edu