It can be a real pain converting to CMYK - and the things that usually suffer the most are rich blue skies etc. Renders from Bryce often tend to appear darker, and more muddy in Photoshop than Bryce, and one of the first things to do is try the AutoLevels function. The results are not always desirable, but you can fade the it down immediately after applying it. But the point is that the levels will have been pushed to their highest with the gamma, and you have an idea of the colour/contrast range in your pic. If you are going have the image printed via a particular company/press type, ask them for their own colour profile files, which should convert your RGB into their specific printers range. It's always best to work on a copy of the original render, and try different methods to achieve the final result that you can compare. Once you become experienced as to what colours are most likely to suffer the conversion, you are often better to convert to CMYK immediately (or use the proof setup preview in PS) and do all you contrast and colour tweaks in the colourspac that the image will be printed in. I use LZW compression all the time, and I have never noticed artefacts - it is supposed to be lossless compression!!?

Adam Benton | www.kromekat.com