Re: Update on HP 10/20PS printers
Re: Update on HP 10/20PS printers
- Subject: Re: Update on HP 10/20PS printers
- From: Johan Lammens <email@hidden>
- Date: Tue, 04 Dec 2001 13:20:37 +0100
- Organization: Hewlett-Packard
neil snape wrote:
>
I'm curious to know if the gamut coming out of the HP10/20 then would be as
>
large as if it were Quickdraw. Would this be a printer for photographers
>
doing display prints and running PS proofs? The Epsons can print out a much
>
larger rgb gamut for photographic prints then while running thru rip to a
>
TAC ink limited linearised inkjet to make a press simulation proof.
There should not be any difference gamut-wise between an RGB interface (QD) with
internal black generation and ink limiting, and a PS interface (RIP) with
equivalent BG and IL. Ink limits have to be applied in both cases, in addition to
BG and light ink generation. In the case of the 10/20ps, you can address all the
gamut available via the PS rip, using either the provided or your own custom
profiles.
To print presentation photo prints with in-rip separation you should choose the
(default) input RGB and output (media) profile and Perceptual rendering intent in
the rip, and send RGB data to the rip (!). To use an output (media) profile
externally for presentation prints, turn off color correction and ABR in the rip,
apply the profile in your app with P intent, and send CMYK data. To print CMYK
proofs (i.e. simulating something else, like an offset press), generate the press
separations externally in your app with the intent of your choice, send CMYK data
to the rip, select input CMYK (press) and output (media) profiles in the rip, and
use Relative or Absolute Colorimetric intent.
The built-in media settings have ink limits, light ink generation, and printmodes
(number of passes, carriage speed, etc) optimized for each media. To use third
party media the general process is as follows:
1. turn of color correction (profiles) and ABR in the rip
2. look for a media setting (name) and print mode that works well in terms of ink
limits, separations, and print mode: no bleed, no cockle, good gradients, etc.
More ink means more gamut, but can cause bleed, dry time, etc problems - you have
to make a good trade-off. You should use your favorite CMYK target for this, and
be prepared to experiment ("waste" a lot of media).
3. run a color calibration (linearization) using the media setting selected in 2.
4. with color calibration (linearization) enabled, print your profiling target
(IT8.7/3 or other), measure the result, and generate a new output profile.
5. load the output profile into the rip and/or your application software and print
as usual (see above), with calibration enabled.
All this is/will be described in more detail in the product documentation.
Johan