Digital BW, The Print

----- Original Message -----
From: "Murray Bulger" <mbulger@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Cc: <cmackay@...>
Sent: Saturday, September 14, 2002 6:22 PM
Subject: [Digital BW] MIS Variable Mix Quadtone Problem


> I teach a new digital imaging a photography course. We have moved
> completely to digital output. We use CFS systems due to the low cost.
> Color has worked wonderfully for us. BUT, my foray into the
> Quadtone/hextone B/W has been quite frustrating. All photos look
> posterized and the grayscale print out has a similar out put for 75-85% as
> found in about 45-55%. I am new to this and may have overlooked something.
> I read (in this group) and tried as much as I could to solve it, but I
> really need help. My students need to be printing within the week.

Murray,

Well that sounds pretty odd.
>
> Here are the details:
>
> 1. Printer Epson 1280 with MIS CFS system withVariable Mix Quadtone
> (Hextone) ink set
> 2. Test paper is Epson photo and our print station uses Photoshop 5
> (upgrading to 7 soon)

Epson photo paper is not a good choice. The inks work much better with a
matte paper. Paul's curves are paper specific to EAM but also work well with
the Hahnemuhle papers. What you are seeing sounds too extreme just because
of the paper but this is the only thing I see in your set up that seems odd.

> 3. Print set up as per Paul Roark's curves for MIS Variable Quadtone
> 4. Inkbottles are properly connected to the appropriate color in the
> cartridge; the labels on the bottles matched the position on the cartridge
> . A purge test in RGB mode of CMYK, pC , pM color bars resulted in the
> following output: K= black; C= darkest gray; M= blue-gray; Y= lightest
> gray; pC = medium gray; and pM = light-blue-gray

That's correct.
>
> 5. The purge test when converted to grayscale and then back to RGB and
> applying Paul's neutral (vmp8-nc16) curve resulted in a gradation from
> very light gray to black for Y, PC, PM, M, C, and K, respectively

When I do this I get Y, PC, PM, C, M, K. Our results seem to reverse the C
and M. Double check if this is indeed true. Use a scanner to check relative
density.
>
> 6. All grayscale sample outputs with color space in grayscale, RGB
> (converted from grayscale), and RGB (color) yielded printouts with similar
> tonal output at the 75-85% range as found in about 45-55% range.

Is your grayscale gamma in PS set to 2.2? If not there will be a gamma
mismatch when converting to sRGB or RGB space which have a gamma of 2.2.
>
> 7. I tried to correct the grayscale problem with a transfer function, but
> the tonal differences are too strong.

That should not be necessary. Something else is wrong.
>
> Questions/Thoughts:
>
> 1. Are the inks possible in the wrong position in the cartridge (checked
> many times and it follow the pattern on the cartridge and as per Paul's
> instructions)?

No because you get the correct ink colors when printing the purge file.

> 2. Am I possibly missing something in my set up in PS %, the printer
> driver, or the curves?

PS gamma settings perhaps.

> 3. The printer has had some USB related interruptions (seems to work fine
> now) and I think it may be suspect, although it printed colored photos
> well although partially at times.

Not a factor.

> 4. Can the F-16 chip resetter cause problems?

No the chip setter doesn't effect output. If the chip isn't reset the
printer doesn't run.
>
> I truly hope someone can shed light on this problem or set me in the right
> direction. Like many of you, I prefer to spend my time creating or
> teaching. Any help would be greatly appreciated.

I wish something leapt out at me here but only things that come to mind are
the paper and the possible gamma mismatch. neither of which would account
for such a strong tonal mismatch. Have you tried printing out 21-step
wedges? You can find the file on the MIS site or on the group's homepage in
the Files section in the folder:

Files > Image processing

Martin Wesley