Why is PowerTrapper giving me this warning, "Blending happens in ICC Based colorspace in Transparency which can give difference when done in Device CMYK", and how can I correct it?
The message is not necessarily from PowerTrapper. Most likely you are sending a non-Normalized PDF file to PowerTrapper and since PowerTrapper will only trap Normalized PDF files, “OnDemand” Normalization is done.
It is this Normalization process that is throwing the warning.
Check your input file for Blending that uses ICC based colors. During the Normalization process they are converted to Device CMYK. During the conversion the ink values of the blend might be different from the values when it was created.