As X applications which use colour are sometimes unable to grab all the colours they require (due to other applications using them) you may find that the 24-bit colour images (such as colour jpegs) look much better on your screen if you first convert them to 8-bit images, and then select "Use Own Colormap" from the "Display" menu. This will likely mess up the colours for the rest of your screen when the focus is in the xv window, but it will allow xv to display images more accurately.
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