discoloration of jpg

Hi all!
I'm a relative newbie with imagemagick, and I am encountering a strange problem when converting a series of tiff images to jpeg.  In the converted image, the light brown of the original is replaced by purple.

You may see an example at http://umedia.lib.umn.edu/node/85828

Click on the image, and you will see a jp2 rendering that shows the original colors.

Even stranger, the image displays correctly in Safari, and incorrectly in Firefox.  Windows browsers show a purple image as well.

I have used a few different versions of IM (all 6X) with the same result.  The convert options are very vanilla -- I have only a --resize option.

Any ideas on what options to experiment with or other things to check to convert this image?

Thanks in advance!
Bill