The settings you see in
the screen-grab below are generally accepted as the safest
choices (although not necessarily the defaults that you will
obtain when you first install Photoshop, so please check), and
will enable you to avoid virtually all image data damaging
scenarios that you may encounter when opening files from
whatever source. One interesting point about Embed Profiles
and certainly one to keep in mind. If you deselect the option then
Photoshop (so far as I know no other program does this) WILL embed
a profile, but this profile will be a special profile indicating to
Photoshop that the user made this choice. When you open such an image you
will NOT get any warning messages, etc., this is quite deliberate
and also a good thing.
Profile" section is where we tell Photoshop how it
should deal with images that contain no embedded profile.
It doesn’t actually do very much other than flag up the "Missing
Profile" dialog as shown below, and even this only
happens when you open an actual image. Of course if we have set
the "Profile Mismatch Handling" section to
something other than "Ask When Opening", it
will totally ignore the fact that the file has no embedded
profile and open the image in a colour space previously specified
by you in the "Assumed
Profile" RGB pop-up
window. So it is important that you ALSO adhere to the following
advice on "Profile Mismatch Handling". You
should consider the "Missing
Profile" and "Profile Mismatch Handling"
sections as "safety nets", they're designed to slow you
up and make you think.
In the example below the image contains no embedded profile, if you
don't know the source then select "Don't Convert". If you
do know the source then make that the selection in the "From"
pop-down window then choose "Convert". Typically an image
scanned outside of Photoshop will cause this dialog to appear. If the appearance
of the image changes drastically in colour or density you made the wrong
choice, you can use Photoshop "History" to get you back
to original image.
Example - opening an image with
"no" embedded profile
The final section of the
Profile Setup dialog is the "Profile Mismatch Handling"
section. Get the settings in this section wrong and, your image
data is very likely to end up in a less than optimal state. For
each of the three pop-up windows we have three choices, "Ignore",
"Ask When Opening", and "Convert".
Taking each of the
options in turn:
– This option simply opens the image in your current RGB,
CMYK or Grayscale workspace without any conversion of the
image data. At first this may appear to be a perfectly
reasonable choice, but note, by not allowing a colour space
conversion we are in fact changing the "Colorimetric"
meaning of the image data thus it will appear on your
monitor and print differently from what it would have done
on the system in which it was created.
When Opening" – With this option, if
you open an image that has the no profile embedded
within it, you will be
presented with dialog similar to that shown above. If the
file has an embedded profile, but it's the wrong profile,
then you will get the dialog shown below. It will be displayed in the "From"
pop-up window. The "To" pop-down window will
usually be "YOUR" actual Photoshop "RGB", "CMYK",
or "Grayscale" colour space depending upon which mode,
etc. you are currently working.
to ----- C" – This is the most dangerous
option in that it allows Photoshop to automatically convert
the file you are opening "From" and "To"
the colour spaces you specified in the "Assumed
Profiles" section. For most this is not the best
option for very obvious reasons (e.g. a calibration image
will automatically be converted into your current work space
thus destroying it).
Example - opening an image with
the "wrong" embedded profile
The example above shows that the embedded profile within the image is
"Adobe RGB (1998)", since the Profile Mismatch dialog appeared
we must make one of two assumptions depending on the workspace you're actually
1. You are using a colour space other than "Adobe RGB
(1998)", e.g. ColorMatch, sRGB, etc.
2. The profile is NOT what it claims to be. This actually occurred
with the original Nikon version of BruceRGB, so don't dismiss it as a
If the dialog appears,
and unless you have very good reason to do otherwise it is
recommended that you leave the Engine: at "Built-in",
Intent: at "Perceptual Images", and "Black Point
Compensation" at "On" at all times.
the "Missing Profile" and "Profile
Mismatch" dialog boxes are designed to WARN
you that something is amiss, they will only appear when you open
an actual image, and not when you are configuring "Profile
specifically part of the Color Settings menu, "Profile-to-Profile"
(P-to-P) does form an essential part of the colour management
system, and is found under the Image/Mode menu.
Profile-to-Profile is a very powerful tool in that it
effectively lets you convert an image between any two colour
spaces, as and when required. However, there is also a "Health
Warning" that needs to be considered – "Photoshop
does not keep track of any colour space conversions undertaken by
P-to-P", which means that the user could potentially
save an image with the wrong colour space profile (tag)
embedded within it (remember, that unless you specify otherwise
the profile saved with an image will be that of your current
Photoshop work space).
pop-up is where we select the "Source" colour
space and the "To" pop-up the "Target"
It is also generally
recommended that in Profile-to-Profile mode you specify the
specific "To" and "From"
spaces (e.g. From: LS2000Scanner - To: Adobe RGB (98) rather
than From: LS2000Scanner - To: RGB), even if Adobe RGB (98) is
the colour space you have chosen in the RGB setup dialog as your
Note: It is normally
best to keep "Black Point Compensation"
Unchecked when converting from scanner profiles.
a more comprehensive explanation on scanning workflow see
Bruce Fraser's Article at:-
- For a comprehensive
explanation on what each of the colour management "Engines"
and render "Intents" actually do, please
refer to Andrew Rodney’s Tips page at:-
three main functions:
- As a time saver,
whereby we find, that having opened a file without colour
space conversion we realise that we should have done so. By
using P-to-P we can avoid closing the file, shutting
down and restarting Photoshop.
- We can also use it to
convert between the native colour space of our input devices
(e.g. scanners) and our current workspace. I mentioned
earlier that some scanner manufacturers (e.g. Nikon LS2000
and LS 30 film scanners) allow you to scan images in the
devices native and usually very wide colour space. The
problem is that Photoshop has no idea what colour space the
image is in because there is no embedded profile, and worse
still no equivalent to "Profile Mismatch"
or "Missing Profile" for images imported
via Acquire mode (i.e. "Twain" or "Plug-in"
modules). So in this situation we must force the colour space
- You should
also note that quite often a P-to-P using the devices "Native"
or even "Customised" profiles could result
in quite dramatic shifts in colour, hue and saturation. This
usually occurs if you have made colour and gamma adjustments
within the scanner software. Remember, if you propose to use
device profiles within your scanning workflow then you must
never make colour adjustments within the scanner software.
Remember also that, what you see in the scanner Preview
window is based on your "monitor space" and
bears no resemblance to the actual colours, etc seen by the
scanner. So if you carry out your colour adjustments within
the scanner software I recommend you use your monitor
profile in the "From" pop-up window of the P-to-P
dialog and not the scanner profile, be warned!
The one rider to my previous statement regarding the need to
use P-to-P when scanning into Photoshop is if you use
software such as LaserSoft's SilverFast, or on your scanner
software is designed specifically to integrate with the
Photoshop CMS, which is unfortunately still a very rare
occurrence, NikonScan 2.5x being an exception. When
configured correctly such software will allow wysiwyg previews.
- The final use of P-to-P
mode is for preparation of print files for output the RGB
printers or film recorders whose drivers do not contain any
form of colour management or were we chose to switch it off
deliberately. A typical example of the latter would be when
using "Customised" printer profiles.
6. Colour Wheel and Colour
Again, whilst not
strictly speaking part of colour management I have decided to
include some basic information on the subject of colour
correction techniques. These are not unique to Photoshop; in
fact much of my colour theory has been gleaned over a period of
twenty years printing Cibachrome prints in a conventional
During those years it
has never ceased to amaze me, how some supposedly intelligent
individuals just came apart (mentally) at the thought of even
trying to identify and correct a colourcast. So before I begin
here’s what I consider to be one of the best presentations of
the RGB/CMYK colour wheel that I have yet to come across. This
diagram has been copied from a book (classified by me as a must
have book) entitled Photoshop 5 Artistry, by Barry Haynes and
Wendy Crumpler. I know it’s a breach of copyright, but just
think of the free advert I’ve just given them .
RGB to CMYK Colour Relationships
significance of both colour spaces; RGB is what we see on our
monitor and CMYK are the inks used to create the various colours
Before we look at the
diagram in use let’s deal with another issue that seems to
cause confusion – the term "complements". As
the diagram shows:-
is the complement of
the complement of Magenta,
is the complement of
What does this mean?,
simple; by reducing "red" we’re actually adding
"cyan". By increasing "magenta" we’re
reducing "green", and so on.
So what makes the above
version of the colour wheel so good? Well just look at the
relationships between RGB and CMY and how they are specified.
Most of us (me included)
appear to have some difficulty in specifying a cast in one of
the CMY colours but virtually none when it comes to specifying a
cast if it’s "red", "green" or
"blue" biased. So in this context I will let you
decide how to interpret the diagram yourself, but remember we
all make mistakes, and its only through finding the appropriate
correction through trial and error that we will ever learn the
true art of colour correction. One "Tip" though, it is
always preferable to make colour adjustments that effect one
colour rather than two, think about it!
At least with this
diagram there’s a better chance that we can quickly establish
the most appropriate correction. I hope it makes the task of
determining the bias of a colourcast all the more easier for you
in the future, so please feel free to Print the diagram and pin
it to your workroom wall for reference.
When it comes to actual colour correction inside Photoshop I think most novices find the
"Variations" or "Color
Balance" dialogs to be the easiest to get to
grips with. However, they don’t really provide you the level
of control required to make accurate colour adjustments. On many
occasions you will find that the colour cast in say the shadow
region is one colour and the cast in the highlight another
The best option for colour correction in that situation is to use
the "Curves" tool, I know it’s a
complicated tool to use, but the sooner you learn to use it, the
sooner you will produce top flight colour corrected images. You
may also find some benefits to be in using the "Selective
Color" controls. I have found two books of
particular benefit when trying to perfect the art of colour
Both books offer a wide
range of advice on all things Photoshop and should form a good
foundation upon which you can further develop your knowledge in
world Photoshop 5, by
David Blatner and Bruce Fraser,
5 Artistry, by Barry
Haynes and Wendy Crumpler