HP DesignJet 10ps, DesignJet 20ps Color Management [ja]

Color Management on the

HP DesignJet 10/20ps

Introduction

The HP DesignJet 10/20ps color
proofers enable repeatable and accurate
color reproduction through the use of a self­calibration feature and color management
profiles. International Color Consortium
(ICC) profiles are standard files describing
the color reproduction characteristics of
input and output devices.These profiles can
be used by ICC-compliant applications,
including desktop publishing programs and
RIPs like the DesignJet. ICC profiles can be
embedded in certain image types including
TIFF, EPS, PDF, and JPEG files, where they
identify the color characteristics of images.
The embedded profiles help maintain consis­tent color throughout your workflow and
can be read by the HP DesignJet 10/20ps
RIP when they are processed.

Perform color correction

The DesignJet RIP software setting that
lets you match colors is the “Perform color
correction” check box (Figure 1).The default
setting is “on” (checked).Turn off color cor­rection (1) if you are printing a color man­agement target to make a color profile of the
printer or (2) if you are color-managing
images in another application such as
Photoshop, a page-layout program, or a
workflow application. Otherwise, use the
color correction feature to get the color
match you want. Settings for individual jobs
can be changed by highlighting the job and
selecting Job Properties (Figure 2).

ICC input profile

Input profiles describe the color spaces
of files to be printed on the DesignJet
(Figure 1a). If a file has an embedded ICC
profile, the DesignJet RIP reads this file and
assigns it as the input profile. Files without
embedded ICC profiles are assigned the
default ICC input profile you select in RIP.

• CMYK profile describes the color space

of CMYK images and vector graphics
printed on the DesignJet that do not have
an embedded CMYK profile.

• RGB profile describes the color space of

RGB images and vector graphics that do
not have an embedded RGB profile.

ICC output profile

The ICC output
profile describes the
printing characteristics
of the HP DesignJet on
the print medium select­ed (Figure 1b).

• Profile. Selection of a

Medium (top of dialog
box) automatically
selects the appropriate
HP ICC profile for that
substrate.The user may
also make a custom
profile of the medium
by printing a color
management target on
the proofer and read­ing this target with a
profiling program.

• Rendering Intent. Rendering intent

describes the way out-of-gamut colors are
brought into gamut. Use relative colori-
metric for proofs that do not simulate the
paper color and for spot colors, such as
PANTONE® named colors. Use absolute
colorimetric if you would like to simulate
the paper color on proofs (e.g., to color
the proof background yellow for news­print or a yellowish paper). Per c eptual is
useful for photographs when the Design­Jet print will be the final output.

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RENDERING INTENTS

•Relative Colorimetric—for proofs
without paper simulation and for spot
colors

• Absolute Colorimetric—for proofs
with paper simulation (e.g., a proof
for newsprint will have a yellow
background)

• Perceptual—for photos printed on
the DesignJet as final output (not to
simulate another process)

Color-Managed Workflow

The “Perform color correction” setting
enables users of the DesignJet 10/20 to sim­ulate a target printing process using a CMYK
profile, or to get printed output that most
closely matches the monitor using the input
RGB profile. In the following workflow sce­narios, assume you are scanning or digitally
photographing images, editing them in
Photoshop, and printing them on the
DesignJet 10/20 in the mode specified (RGB
or CMYK).

RGB
Workflow

Use the RGB work­flow if you would like
to print documents
that most closely
match their appear­ance on the computer
monitor.You will need
ICC profiles of your
scanner/camera and a
standard working
space (sRGB,
ColorMatch RGB, or
Adobe RGB, in order of

increasing color gamut).

RGB workflow is outlined on page 4.

If you later send the RGB images to a
service provider for high-volume output,
these prints should also match the screen if
the provider uses an RGB printer or RIP and
sets the same standard RGB profile.

CMYK workflow

Use the CMYK workflow if you intend
eventually to send your documents to a serv­ice provider for quantity output on a print­ing press or high-volume digital printing
device that uses the CMYK color system.
The CMYK workflow assumes that both
user and service provider aim to print
according to a published color specification,
such as SWOP, Eurostandard, DIC, or TOYO.
The actual profile of the printing press may
differ from the specification, however, due to
variations in ink, substrate, and printing con­ditions. The DesignJet 50 can simulate a pro­filed press (including any deviation from the
published specification), while the DJ 10/20

both assume that the user does not have
access to the press profile.To proof in
CMYK mode in Photoshop, begin with the
RGB workflow, then convert your images to
CMYK using the steps outlined on page 5.

CMYK Simulation
Workflow

The HP DesignJet 50 is designed to sim­ulate a profiled printing process, such as a
printing press, halftone-dot proofer, or other
CMYK process, even if the target process
does not conform to a published printing
specification.The DesignJet 50 RIP uses ICC
Link profiles to tie two processes together
(the DesignJet and the other CMYK printer)
so that one (the DesignJet) may simulate the
other (the CMYK printer).

DesignJet 10/20 users can simulate a
specific CMYK printing device, including
any deviation from a published specification,
but must use the device’s profile in the
CMYK workflow outlined above. For exam­ple, suppose you wanted to simulate a
halftone dot proof such as a Fuji FinalProof
that was calibrated to print differently from
SWOP.To do so,you would need a profile of
the FinalProof and a custom profile of your
DesignJet 10/20 on the substrate you select­ed.Workflow settings for device simulation
are outlined on page 6.

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WORKFLOW

• RGB—For prints that match the mon­itor as closely as possible and where
the DesignJet is final output (not
intended to simulate another printing
process)

•CMYK—For prints intended to match
a CMYK printing process such as a
printing press or CMYK printing
device