Digital BW, The Print

On 9/11/03 2:20 am, "DigitalBlackandWhiteThePrint@yahoogroups.com"
<DigitalBlackandWhiteThePrint@yahoogroups.com> wrote:

> I have downloaded the profiles that Paul has on the MIS website for an Epson
> Photo Stylus 1200. I'm using the variable Quadtone ink sets and have
> everything set up as suggested by Paul's workflow. I have had nothing but
> horrid results. After the first print hit the garbage can I loaded the curves
> back in and went into the individual channels and looked at the way he has
> them bent. After looking at the individual colors and how they are bent, I
> thought I had found the problem. I was having a minor bit of solarization
> going on in mid-tones. So I took the pins out of the Blue curve which were
> bent in a ridiculous manner which was causing the solarization. You can't bend
> curves up and down in a sign wave type of manner and have your tones come out
> without them being solorized. I can't see how anyone can have decent results
> with these curve settings. My shadow area is not continuous; there are blotchy
> spots through out the blacks, no continuous tones. It looks like someone took
> a felt tip pen and made a bunch of dots to create the black area. I just can't
> see how these curves were created and anyone have, like I said, good results.
> I'm professional color technician and have been doing color for prepress for
> over 7 years and can't seem to get this to work. If anyone has ANY advice on
> how these inks and how digital printing with these inks and curve settings,
> please let me know how you accomplished this. Everyone I have asked can't see
> how these curve settings can even come close to giving good results. I have
> had everything set exactly as to Paul's workflow and just can't seem to get it
> right. Conventional printing may be the road I travel again. This is very
> counter-productive.

I use an Epson 1200 with MIS inks (Permajet VTBlax) and can hopefully
comment on your problem. Don't attempt to tweak Paul's curves as they do
work fine - I understand where you are coming from saying 'you can't bend
curves up and down in a sine wave without solarisation' but that is not the
way to think of the individual ink curves - they are ink coverage for
particular tonal values and blend seamlessly with the ink coverage in other
channels. Forget Paul's curves for the moment.

I can repeat your problems if I either forget to assign and sRGB profile to
the greyscale image when I change to RFGB mode (I usually work in Adobe RGB
1998 for colour and get something like the problem you describe if I leave
the colour space set to this default). If you don't have the printer driver
colour adjustment set for Vivid you will also get weird areas of flat tone -
done this too.

The workflow is simple but every step needs remembering.

Greyscale (get the image as you want it)
Convert to RGB mode
Assign sRGB profile
Use Curves to load appropriate Roark curve (screen image from this time on
tells you nothing as it is false coloured)
Send job to printer choosing 1440dpi, Photo Quality inkjet paper, Colour
control Vivid

I made up a sample file with four copies of a well-toned image and four
21-step wedges and applied one each of the Roark curves to the four images.
The first time I printed this and got all the variable tones with full
separation on the 21-step wedges I knew I was doing things right.

--
Regards
David Prakel

Centre of Britain PhotoWorkshops Partnership
www.photopartners.co.uk