Mike Chaney's Tech Corner

Probably an odd conversion that triggers it but when I load a Tiff with ProPhoto space assigned to print to file with AdobeRGB (Printer) ICC as the new color space, Absolute colormetric rendering selected then I get an image with an orange cast. Happens with 8 bit and 16 bit Tiffs. Does not happen with Perceptual or Relative Colormetric, did not try Saturated. Photoshop does not give orange cast in the same conversion.


met vriendelijke groeten, Ernst

New: Spectral plots of +250 inkjet papers:

http://www.pigment-print.com/spectralplots/spectrumviz_1.htm

ProPhoto RGB has a white point of D50 and Adobe RGB has a white point of D65.  I don't see how you can convert from one to the other without getting a color cast if you use Absolute Colorimetric!  The very word "absolute" means you are not "converting" from one white point to another.  Not sure why Adobe's conversion doesn't do the same: they appear to be making a "relative" conversion when it should be absolute.  Simply put, you should get a warm cast if you do an absolute conversion from a D50 space to a D65 space because D50 light (from ProPhoto) will look warm when viewed at D65 (from Adobe).  If you don't want that absolute conversion, then use RC or Perceptual.

Why Adobe is doing it wrong, I'm not sure... I suspect they're taking a "non standard" approach and converting the white point because they know that Absolute Colorimetric intent is of little use to photographers DUE to the way it handles white point.  But I'll stick to the way I do it because doing it the Adobe way is wrong: it's no longer Absolute Colorimetric if you "scale" the white point!

Mike

Mike,

Thank you, I learned something today or better it reminded me of that issue so I can adjust another mistake I made yesterday.

met vriendelijke groeten, Ernst

Try: http://groups.yahoo.com/group/Wide_Inkjet_Printers/

Seems like I've found my solution here.
I'm scanning my patches one more time right now.

I've printed a file embed with Adobe RGB and with A. Colormetric, it came out really cold, specially in the paper based color in the image. And I think the reason is because my ICC file is generated wit D50 illuminant.

D65 -> D50 turns out cold

hopefully I'm right about it [crossing my fingers]

Opsss... seems like it still happening
the image turns out still very cold under the Qimage soft proof... :(

You should never be using absolute colorimetric unless you are producing a single (or several) color company logo or something like that where there are no neutral colors for the media to show through.  An example of that might be printing a Kodak logo where it is getting trimmed and you must get the shade of yellow exactly right and you don't care about media color.  Just remember: "absolute" colorimetric should "absolutely" never be used to print photos.  :)  It is already known that PhotoShop's absolute colorimetric rendering doesn't work.  If you try to print a photo with absolute colorimetric in PhotoShop, it actually uses relative colorimetric.  At least that's what it appears to do.  One thing I know for sure: it doesn't work in PhotoShop.

Mike

Photoshop with ACE as the color engine. All other color engines even in PS behave like Qimage so Adobe is the odd one out.


met vriendelijke groeten, Ernst

New: Spectral plots of +250 inkjet papers:

http://www.pigment-print.com/spectralplots/spectrumviz_1.htm