Datacolor User to User Support Group.

This is an old thread, but my question ties into it. I have been
trying to profile Canon iP4500 and iP4300 printers, with both OEM and
Image Specialists inks. It quickly becomes obvious that these printers
suffer in reproduction of dark saturated colors, especially reds and
to lesser degree greens. Not so bad in yellows and blues. With OEM
profiles, the way Canon gets around this is by having perceptual
rendering quite a bit lighter then actual colors, which brings dark
colors into gamut. This is just eyeballing soft proofs and a few
output samples. I don't know really if Canon does this with images
when all colors are in gamut. These printers suck and most images have
plenty out of gamut. The main difference is in how OEM and Colorvision
differ in perceptual intent, with OEM being about a stop too light.
Other intents look about the same between OEM and Colorvision.

The end result of this, due to how poorly these printers render dark
saturated reds and browns is that none of intents made by Colorvision
look photographically natural. Not that colors don't match source, but
relationships between colors look unnatural. For example, if someone
is wearing a red sweater, in folds of the fabric where red is in a
shadow, it looks weirdly brown/grayish in all intents (some more some
less, but none satisfactory). With OEM perceptual, all colors are
wrong (mainly in that they are too light, but also in hue and
saturation), but at least they preserve relationship between colors
and it looks believable.

I would suggest that Colorvision perceptual rendering shouldn't match
on just hue and brightness and ignore saturation (if that is how it
works, although I suspect that explanation given below is simplified).

In a difficult situation at least the way OEM perceptual works is
effective. How can similar results be achieved with Colorvision
profiles, without bringing each image into gamut by hand (which is
fine for exhibition, but not when I want to print 100 vacation
snapshots for my mom)?

Marko

--- In colorvision_group@yahoogroups.com, CDTobie@... wrote:
>
> 
> In a message dated 11/14/07 12:31:47 PM, ryannd@... writes:
> 
> 
> > On the profile I made with PrintFixPro the bright yellows
> > (especially around the sun in the sunset picture at the lower left
> > but all yellows in other parts too) are muddy and have lots of black
> > in them on perceptual and look good on saturation intent. And the
> > prints look just like the soft proof--unusably muddy on the yellow
> > colors with perceptual rendering.
> > 
> > You guys off course recomend saturation and not perceptual intent on
> > rendering and that works fine for CS3.  Unfortunately I do almost
> > all my printing with Lightroom which doesn't give me a choice of
> > saturation -- it's perceptual or relative only as rendering intent
> > with Lightroom.
> > 
> > Help!
> > 
> 
> In one sense, this is a Lightroom issue, in that they do not support
the full 
> list of intents. What is happening is that you are asking for out of
gamut 
> yellows, and the match is being selected based by Hue and
Brightness, without an 
> emphasis on Saturation, in our Perceptual intent. The color with the
closest 
> density and hue angle does not suit you. Between now and the next
major update 
> to Spyder3Print, there will not be any changes to our color engine,
so what 
> you get is what you get, for the time being. This is only one of
several 
> reasons I don't print from Lightroom.
> 
> On the other hand, the test images you note are filled with
oversaturated 
> colors, colors that you don't actually find in photos, only in
vector images and 
> heavily adjusted images. This test image has lots of yellows that
hit 255 red, 
> and well over 200 green in AdobeRGB. Not colors you're likely to
bump into 
> with actual images. So be sure this problem is a problem for your
own files 
> before you panic, based on this over-the-top test image. Don't judge
the 
> "reasonableness" of these test image yellows by looking at them on
your monitor. They 
> are all outside the gamut of a typical display; most are also
outside the gamut 
> of a Wide Gamut Eizo display...