LAB color is not supported by ImageMagick at this moment.
Convert files with different colorspaces / colormodels: Check the colorspace of the original file and load this and a RGB colormodel using the -profile option. (this requires .icc or .icm files)
Convert PSD to JPG: When converting a PSD to a JPG format always make use of the -flatten command in ImageMagick, this makes sure the layers are removed.
Convert EPS to JPG: When converting a EPS, you need to have w:Ghostscript installed.