management: Implementation part 2:
Jan. 14, 2004
profiling, workflow details
The series begins with an Introduction
to color management and color science. Implementation
part 1 describes how to set up color management and
that describe the color response of a device or a color
space). It features Picture
Window Pro, but also includes information on Photoshop. Implementation
part 2 (this page) discusses monitor profiling and
The series continues with Obtaining
ICC profiles and building them with MonacoEZcolor
printers and ICC profiles.
to Dennis Wilkins and Jonathan Sachs for excellent suggestions and
profiling and calibration
properly calibrate and profile your monitor, your video card should
have a color lookup tables (LUT). Most recent cards have them. If yours
doesn't, go out and get one that does-- even inexpensive cards have
nowadays. If that isn't practical, consult the Color
Management tutorial, pp. 19-26, for options.
This is a good time to clarify the distinction between monitor
- Calibration involves
setting the display, which comprises
the lookup table (LUT) and monitor, to operate at a specified standard,
for example, at a white point of 6500K and a gamma of 2.2. Calibration
typically involves setting controls on the monitor-- Contrast,
(also called Black level) and Color temperature-- and loading values
the LUT. Monitor settings are summarized
the calibration process is detailed in the Monitor
calibration and gamma page.
Windows recognizes a Default monitor profile,
which is used by most LUT loader programs and some image editors,
its existence has no immediate effect on monitor calibration. You can
the Windows default monitor profile by one of two routes. Open the
Panel, then click on Display,
management. Alternatively, right click on the screen
(wallpaper), then click on Properties,
management. The Current monitor, the Default monitor
a list of ICC profiles associated with the monitor are displayed.
a display involves
describing the colors and tones produced by a calibrated
in response to numeric data, and storing the characterization in the Monitor
profile. This allows an appropriate
to be performed when an image is sent to the display. Since the
display comprises the LUT and the monitor, "display
be a better description.
There is a good deal of confusion for a simple reason: Monitor
often contain information used by LUT loader programs to calibrate the
monitor; hence they play a role in both calibrating
and characterizing it. And the
characterization stored in
the profile plays a role in altering the image sent to the monitor, as
Image flow from memory to
There are two places where an image can be altered on the way
image editor to the monitor.
the image editor, under control of the color engine. If color
is enabled and a profile (other than None)
is specified in Picture Window Pro's Monitor
Profile setting, the image will be mapped from the working
space to the monitor profile space. The Monitor
Profile setting affects the display for PW Pro only.
6 uses the Windows default monitor profile for this purpose.)
The best way to learn how monitor calibration and profiling
display is to try out different settings. I recommend downloading the
chart on the right and opening it in your image editor. It is a
diagnostic tool that provides an accurate indication of gamma and black
level. Instructions can be found in the Monitor
calibration page. The chart works for monitor display only,
hardcopy. For color I've included simulated GretagMacbeth ColorChecker
charts in two color spaces, sRGB and Adobe RGB (1998), at the bottom
of this page.
- In the color lookup table (LUT),
be set by LUT loader
programs or by video card software as a part of the calibration
LUT settings affect the appearance of the display for all
Several programs calibrate and profile
monitors. These include
SpyderPro with OptiCAL, and GretagMacbeth
Eye-One Display, and Profile Mechanic - Monitor. These programs are described in more detail in the Monitor
calibration page. All of them measure the monitor with a
then create a profile with instructions for loading the LUT. This
is set as the Windows default monitor profile. Shortcuts to their
LUT loader programs are placed in the Windows startup directory. I have
which installs MonacoGamma as its LUT loader.
The LUT can also be loaded ay other programs:
QuickGamma (which I recommend
for beginners who don't yet have colorimeter-driven software), Adobe
(installed with Photoshop and run from the Control Panel), and video
software. These are discussed in the Monitor
glitches: Some monitor profiles have
incorrect values for
gamma in their TRC
Response Curve) tags, described above in Anatomy
of a profile. I've encountered two cases of interest.
- Monitor profiles generated by
MonacoEZcolor 2.1 and 2.5 had LUT loader
instructions that set display gamma to 2.2, but had TRC curves with
= 2.0 (on my computer). This was an error, corrected in
When I used the MonacoEZcolor profile as the Monitor profile in PW Pro
(or used it as the Windows Default profile, which is recognized by
a gamut mapping took place that boosted the visible display gamma from
the correct value of 2.2 to around 2.5.
of generic monitor profiles. It's
always a good idea to check the TRC tags in monitor profiles with ICC
especially if you see inconsistencies
in the display gamma. Another glitch: MonacoGamma doesn't always work
my ATI Radeon video driver software has been used to set the LUT. Adobe
Gamma works more consistently. Since both these programs use the
tags in the Windows default monitor profile, I use Adobe Gamma when I
to set the LUT after I've booted (using the profile created by
Are we having fun yet?
- Monitor profiles formerly available from Sony's support website had TRC curves set
for gamma = 2.5: inappropriate for a monitor calibrated to gamma = 2.2. If you happen to be using an old Sony profile, beware.
Images in non-ICM aware programs are assumed to have the sRGB
space. No gamut mapping takes place when they are sent (through the
to the monitor. This works reasonably well because CRT monitors are
close to the standard sRGB profile, sRGB
viewing conditions (a review) Since
one of the principal goals of color management is to produce prints
match the monitor image, correct monitor viewing conditions are vital.
More detail can be found in Monitor
monitor should be operated
in subdued light; dark areas of the screen should appear dark to the
your monitor's color temperature
(white point) to 6500K, D65, or sRGB, which is equivalent to 6500K. The
5000K setting appears too dull and yellow on most CRT monitors.
display adaptor software
should be set to 24 or 32 bit color (True Color).
Task Lamp with a 4700K 36 degree 50W bulb for viewing prints.
has a CRI (color rendering index) of 0.98.
At the 6500K monitor setting, a white sheet of paper viewed under the
lamp looks a tiny bit yellower (warmer) than white areas on the monitor
screen. This is not a problem since the eye adapts quickly when moving
from the monitor to the print.
lamps: Two promising choices are Ott-Lite's
series, which has a color temperature of about 5300K and CRI = 0.95, and Sunwave
5500K fluorescent bulbs, which come in both tubes and compact screw-in
models, have good brightness and CRI = 0.93.
The Philips 287813 15 watt screw-in daylight compact fluorescent bulb:
5000K, CRI = 0.82, is available at Home
Depot, SKU #652746, about $15. It's quite bright. Other
a halogen desk lamp nearby to see what the print will look like in
the Contrast to maximum
unless the image is too bright or harsh.
the parameter that describes the nonlinear relationship between image
and monitor brightness, and Brightness
(black level) using the Gamma
and black level chart. Several
are available. There is some interaction between brightness and gamma
so you may have to go back and forth between them.
management workflow details
Once you've chosen appropriate settings, you
ignore color management most of the time, but there are instances where
you need to pay attention. Refer to the diagram below
for the big picture. (To be
added: manual adjustments with scanners and digital cameras. Update
the effort involves obtaining
or building appropriate profiles. This includes profiling
printer/ink/paper combinations, film scanner and video camera (if you
one). Profiling film scanners is optional for situations like landscape
photography with negative film, where there is no control over the
but it can be useful for studio photography with slides.
Window Pro. You may want to
open the Color Management Settings dialog box at the start of an
session to make sure it contains appropriate settings. You may keep it
open if you wish.
- Scanning. If your are
using a scanner
profile you have two choices.
1. Select the scanner profile and target color space in the scanner
if permitted. 2. Select it in PW Pro's Assumed Scanner Profile box. Do
not select both.
- Opening files. If a
file does not have an
embedded profile with
the (default) working color space, you will be asked if you want to
You answer depends on the context. If you are preparing images for
display, the answer will probably be "no." If you are preparing images
for high quality printout and your (default) working color space is one
with a larger gamut than sRGB, your answer will probably be "yes."
The Working Color Space in the
Color Management settings box is the default or preferred setting. To
the actual color space of an image, i.e., the
(if any), right-click on the image and click on Display Info.
color profiles. You may need to attach a profile to an image
its color space, for example, when you are working in a color space
than sRGB and need to prepare the image for the Web. To change an
color space in Picture Window Pro, click on Transformation,
Color Profile... This brings up the dialog box shown on
You can choose between three Change
Data and Profile
Setting (the default) is shown. This is the setting you'd
convert from one color space to another.
- Profile setting only.
Used to tag an image that had no profile setting or an incorrect
setting: For example, Canon's File Viewer Utility can convert RAW
to Adobe RGB (1998), but it doesn't tag the image files. This makes
almost inevitable, since untagged images are (by default) assumed to be
- Image data only
Rarely used, but you might find it instructive when you're learning
In Photoshop 6
the equivalent operations
Profile...(changes profile setting only; used to attach a
or Convert to Profile...
data and profile setting).
- Soft-proofing is
a technique for previewing
the appearance of prints on a monitor. It works best for 4-color offset
printing, which has a smaller color gamut than most CRT monitors. It
limited applicability to high quality inkjet printers, which have a
gamut, and hence can reproduce a number of colors outside the gamut of
most CRTs. It can, however, give a rough idea of the overall appearance
of the final print, and it can also be useful for comparing profiles.
example it reveals a difference in tonal balance between different
for the Epson 2200 with Premium Luster paper.
Soft-proofing should be disabled for most
operations. Turning it on should make a rather subtle difference in
appearance. If the change is major, check you settings. Carefully
soft proof images with prints. Soft-proofing is strongly dependent on
quality of the profile; it's not 100% accurate. But it can get you 50%,
or if you're very fortunate, 90% of the way toward matching the print.
In Picture Window
Pro, the Proofing
Profile setting in the Color
Settings dialog box is normallly set to None
to disable soft-proofing. To enable it, select a printer profile (the
profile you plan to use for your printer/paper combination) for Proofing
Profile, and select a Proofing
Intent, usually Maintain
(perceptual) or Preserve
and White Point (Relative Colorimetric). (I find Picture
Pro's non-standard nomenclature to be somewhat confusing.) Proofing is
applied to all open images. Be sure to reset Proofing
Profile to None
Photoshop does a
more convenient job of soft-proofing.
You'd expect as much because Photoshop is aimed at the printing
where soft-proofing is an important part of the workflow. To enable (or
disable) soft-proofing, click View
and check (or uncheck) Proof
I find this to be very convenient. To select a proofing profile and
intent, click View,
You can find
more details by looking up Soft
in the Adobe Help index. Soft-proofing only applies to the images
while settings are chosen. You can use Image,
to make a copy of the original image for comparison.
Associated profiles are embedded
in files saved in BMP, TIFF,
JPEG formats. (BMP is obsolescent; it's not generally
You should be able to select the
printer profile either in the image editor (in the PW Pro Print dialog
box) or in the printer driver. The latest release of the Epson 2200
driver software (v. 5.40+) allows you to apply the ICC profile of your
choice, but I don't recommend it because it has bugs. Do
not apply the printer profile in both places.
The Print dialog box (the
last box you see before
printing starts; right) asks you for the printer profile (below). These
two entries appear only when color management is enabled. Your answer
not saved. I would prefer to be able to enter a default printer profile
in the Color Management Settings dialog box, then have to option of
it when I print. You must be certain that your printer driver settings
are identical to the setting used to create the profile. You should
them with a similar name.
management is enabled and your image files are in
color spaces other than None
you must use a custom pofile; you should not print
with Color Adjustments
as detailed in Printer
If you don't use a custom profile the printer driver will assume the
data is in sRGB color space. Images in larger gamut spaces will appear
with Photoshop 7 by John
occasionally get questions on the subject.)
7.1 there are two techniques for applying ICC profiles to color managed
prints. I have used both successfully on the Epson 5500 and 2200.
first method (which I
no longer use) is,
learned this method at a seminar
last year given by Printing
& Imaging Association Mountain States.
on Image -> Mode -> Convert
to Profile to change the image's working or source profile to the paper
to 'Print with Preview.'
Make sure 'Show more options' is checked. Change the drop down list to
'Color Management' and set the destination profile is to 'Same as
Typically, select Perceptual rendering intent. If your image has
colors, you might want to try Relative Colorimetric.
on 'Page setup.' Select
the correct paper size and paper source.
turn off color management (very important), and make sure that the
media type is selected.
preferred method is to not change the
working space of the
image to the paper space. I use the above method except that I keep the
Adobe RGB (1998) working space and enter a custom profile in the
working space field (in the Color Management dialog.)
Australia RGB Print Guide PS7 (Windows version) and
version cover printing with Photoshop 7. The
Australia RGB Printing Guide (Windows version) and Mac
version cover printing color_management_2.html
diagram of a color-managed image flow is shown below. It's not simple,
but I've tried to structure it to be somewhat comprehensible. Boxes
represent sources or destinations and boxes that alter color have
appearances. See the Legend at the bottom. A simplified version is above.
ColorChecker test pattern
chart is widely used for matching photographic images. I offer these
two downloadable images to help you learn color management-- so you can
see what happens when you convert between color spaces with different
intents, etc. To take full advantage of these charts, you'll have to
an original. The pixel values calculated
by Bruce Lindbloom from measurements of a new ColorChecker with a calibrated
X-Rite 938 spectrophotometer. According to Bruce,
data, printed on the sheet that comes with the ColorChecker, is not
SMPTE-240M embedded profile (same as Adobe RGB
All colors are within gamut. You can check the pixel values, copied
Lindbloom's table for Adobe
(1998), with the PW Pro eyedropper.
colors in this chart should look undersaturated
in web browsers, which are not ICC aware,
but they should
look correct-- nearly identical to the sRGB image below-- in a properly
set up ICC-aware application.
sRGB. Cyan (third
row, right) is out of gamut. Colors
were derived by converting from SMPTE-240M (above) with colorimetric
intent. They are close to Lindbloom's values but not exact; the error
out of 255) is typical for 24-bit color file gamut mapping. If your
is well calibrated, this chart should appear nearly identical to the
chart viewed under appropriate lighting (except perhaps for
patch, third row, right, which is outside the sRGB gamut).
and text copyright (C) 2000-2013 by Norman Koren. Norman Koren lives
in Boulder, Colorado, where he worked in developing magnetic recording
technology for high capacity data storage systems until 2001. Since 2003 most of his time has been devoted to the development of Imatest. He has been involved with photography since 1964.