GrahamWelland
Subscriber & Workshop Member
:OT: Surely we are talking two different things here. PPI is the input file (from my perspective) but DPI is what the printer lays down on the paper. They aren't the same thing.
I was always told to make it easier for the printer driver to interpolate input files to output DPI so hence the Epson, Canon, HP recommendations of multiples of 180 or 150ppi. For example, for my HP that would be 300 or 600ppi. For Epson thats 180, 360, 720ppi. etc etc.
I haven't done exhaustive testing but I've trusted in prior best practices for basic drivers and also PS interpolation vs the driver. As mentioned though, ImagePrint (and doubtless other dedicated RIP/drivers) did all of this internally for superb results.
I was always told to make it easier for the printer driver to interpolate input files to output DPI so hence the Epson, Canon, HP recommendations of multiples of 180 or 150ppi. For example, for my HP that would be 300 or 600ppi. For Epson thats 180, 360, 720ppi. etc etc.
I haven't done exhaustive testing but I've trusted in prior best practices for basic drivers and also PS interpolation vs the driver. As mentioned though, ImagePrint (and doubtless other dedicated RIP/drivers) did all of this internally for superb results.