Colour scaling in imshow

[John W. Eaton]

On 16-Jan-2011, Jordi Gutiérrez Hermoso wrote:

| There's currently a bug in imshow where
| 
|      x =rand(100:
|      imshow(x);
|      figure;
|      imshow(x,[0,255]);
| 
| produces two identical images, whereas the second one should be almost
| black. Attached is a patch that seems to fix this. I'm not sure this
| is the right fix, so I won't push it right away. Notice that I also
| had to ensure that display_range was a double despite the warnings in
| the code that it was wrong to do. Without it, the scaling operations
| that use display_range were not working properly, due to the vagaries
| of integer division.
| 
| I'm not completely sure the attached patch is the correct one, so I'll
| wait for review before pushing it.

Does Matlab set clim to [0, 1] for this case?  If not, then this is
not the right fix.

jwe