Looking for confirmation of Perceptual vs Relative Colormetric when printing.

[TRDannic]

Thanks to this forum I have a better understanding of printing consistently on my new Canon iPF8400, but still have one lingering color management question. Before I can ask the question, let me give you the facts:
1) I generate images on a digital camera using raw format (so far no profile is necessary).
2) I import into LR 5.2 and immediately export to PS CC for edit as an sRGB 16 bit image.
3) I set the proofing profile to the Canon iPF8400 for matte canvas (media I print on) (both relative colormetric and perceptual)
4) I validate with the PS CC gamut warning that nothing is out of the gamut (both relative colormetric and perceptual)

That being said, as I understand it, both Perceptual and Relative Colormetric convert the image colors that are out of Gamut to be in gamut (albeit in 2 different ways) before they are displayed or printed.

My question is: If an image is completely within the printers gamut why does it print differently when I print as Perceptual vs Relative Colormetric?

[Manfred M]

So far as I understand it; both handle out of gamut differently. I don't use a Canon printer so I don't have a feeling the output from these printers. The printer manufacturers implementation of the rendering intents is proprietary. I usually use ProPhoto or AdobeRGB, rather than sRGB in Photoshop; my screen is a wide gamut monitor, so I tend to work in one of the wider gamut settings while editing. If I plan use a commercial printer, I will convert to sRGB (because they usually only work in sRGB), but that is not necessary when I do my own (I have an Epson 3880).

Perceptual colormetric intent preserves the gray balance but either compresses or expands the colour data from the source to destination colour profile. This means that colorimetric accuracy is NOT preserved, but the relative colour rendering is "more pleasing".

Relative colormetric intent preserves colormetric accuracy, but clips out of gamut colours. In general this setting will result in more saturated colour rendering.

Bottom line is that the setting will deliver different looking output, and I will soft proof to get me started but often end up doing a test print using different settings. When I print, I find that I tend to prefer the look of perceptual intent in most of my work, although if I am doing aprint with funky fall colours, I will sometime go with relative intent.

[TRDannic]

Thank you for the quick response GrumpyDiver but the simple way of asking my question is... If an image is within the color gamut of the printer, why would perceptual render a different print than relative color metric? It would seem that if no color conversion were necessary, both images would look the same...

[pnodrog]

https://www.cambridgeincolour.com/tu...conversion.htm

[Dusty]

Have you calibrated your monitor to your printer for either RGB or sRGB?

[TRDannic]

Everything is properly calibrated with xrite tools.

[pnodrog]

I assume in step 2 - sRGB (not a colour space I would bother with at 16bits) - you have a file that is beyond the printers gamut.

Both conversions should pull the image into the printers gamut and also proof as in gamut but the results are highly likely to be different. If it was possible to compare them side by side on the monitor when proofing you should be able to observe the difference at that step.

[Manfred M]

I think you missed the point of how perceptual works; it takes the source image and normalizes (maps) it to the printer gamut. If I remember correctly, printer gamut is wider than sRGB, so it would recalibrate your image to the widest range that your printer can produce. While you say, no conversion is necessary, this is not the way that perceptual is designed; it will alway expand or compress your input file.

Relative leaves things alone other in places where the original is out of gamut, and it clips the out of gamut colours.

Effectively, the two colour intents are unlikely to ever produce identical results. It would be interesting to see how two AdobeRGB files would print, as this colour space is probably closer to your printer's colour space than sRGB.

[TRDannic]

Thank you very much everyone, great information!

[DanK]

I print from Lightroom, and its softproofing module lets you switch back and forth between the two renderings. The effect will of course vary depending on the paper (different papers have different gamuts) as well as the image. I only fuss with it if I have a lot out of gamut, which LR will show you on screen.