Hi Andrew, thanks a lot for your reaction. I have a Windows 7 machine, but I followed your suggestion as outlined below.
In Lightroom I used an image of a bunch of color patches and printed this image to a jpeg file using different profiles and both relative and perceptual rendering intents.
The profiles I used as examples are:
- Ilford: n_GPSGP12_EPSr3000_EPGn
- Epson: SPR3000 Epson Premium Glossy
- Home made profile for Epson R3000 and Ilford GPSGP12 paper (Colormunki + ArgyllCMS)
A single example of the resulting 'JPEG prints' is attached (Ilford profile).
The differences between the 'prints' made with relative and perceptual intent are also attached (subtracted perceptual from relative). The Epson profile, as well as my home made profile, does show clear differences between the two rendering intents. In the case of the Ilford profile differences are present, but they are very small indeed.
So, I was wrong in the sense that the two rendering intents of the Ilford profile are not identical, but the difference is extremely small. One could say that this analysis illustrates the rather significant differences in algorithms used by different companies, or methods, for color 'compression' in the perceptual rendering intent.