CR2 conversion changed from 6.2 to 6.5

[cpacker]

Conversion of CR2 files (Canon RAW data)
yields different RGB values with ImageMagick
version 6.5.4-7 (included in the Fedora 12
Linux distribution) compared to version 6.2.5
(in Fedora 5). The later version yields
values that are lower, for a given pixel,
than the earlier version. If the values were off by a
constant, it wouldn't be that much of a problem.
But the relationship is nonlinear. A pixel in the
midrange of brightness now converts to RGB values
that are about 90% of the values for the same
pixel converted by the earlier version. For
example, a pixel having RGB values of 29516,
32063, 34910 has values 31199, 35862,
41673 in the earlier version. But if you go
either way in brightness -- darker or lighter,
a pixel in the later version falls off, compared
to the earlier version. The brightest pixels are
about 75% of what they are in the earlier version.
At the lower end of brightness, the new values fall
WAY off. For example, a pixel that converts to
7057, 4690, 3982 in the early version now converts
to 3433, 226, 22. What's going on?