Re: ICC profiles and digi-cam


Lee Varis
 

Hi all,

I have been a working commercial/advertising photographer for 25 years
and have been involved in digital imaging for the last 15 - capturing
photos digitally almost exclusively for the last 2 years. My current
views on digicams, icc profiles, ect.. in response to some of the
questions in this thread:

regarding white balance and profile issues:

The E10 has seven white-balance settings, plus "manual" and "raw".
Would you need seven different profiles, or does it depend more
on having a good *match* between the white balance setting and
the actual lighting conditions?
White balance for digital camera files is intended to match the color
response of the capture to the color temperature of the light source. It
is relatively easy for manufacturers of digital cameras to build into
their software "developers" a number of different color responses - this
means more choices for the photographer which is mostly a good thing.
White balance is kind of like applying a profile to the "raw" data. The
danger is that one can easily overcomplicate the whole thing. You can
create profiles to use with every white balance setting which becomes
sort of like applying profiles on top of profiles. The thing to remember
however is that for most of the history of color photography a choice
between "daylight" and "tungsten" has been good enough to get high
quality images that could be scanned and converted into good color on
press even without profiles.

If you used the "manual" setting
all the time (ie, point the camera at something white and push a
button that says "define this as white"), could you use one
profile for everything?

Most consumer oriented digital cameras do some sort of "auto" white
balance where the brightest thing in the scene is assumed to be white
and the color is neutralized to that. This works surprisingly well for
scenes with a full range of values. It will fall apart where you have
more limited value ranges or monochromatic scenes with a dominant hue.
If you know the color temperature of the light and you can pick a
setting that matches it you WILL get a color response that will render a
neutral gray as neutral. In the real world nothing is ever very certain
and picking a color setting manually is a guess at best. If you can
perform a "manual" white balance you are way ahead of the game. Almost
all digital cameras will perform as well as film does in delivering
neutral color for most scenes even without icc profiles. This does not
mean that digital captured color will be perfect any more than
Ektachrome will capture prefect color every time. With high end digital
cameras you can capture a target (like a Macbeth color chart or a
Munsell chart) that has neutral gray patches and calibrate to the gray (
forcing RGB values to be equal). Once this is done a camera file can be
opened up in Photoshop and assigned any of the standard working spaces
and give you a very reasonable starting place for color. The only time a
custom profile will be of any value is when you desire to work with 16
bit "raw" data from the camera in Photoshop. The short answer is that
you CAN use one profile for everything that has been manually white/gray
balanced or you can simply ASSIGN one of the standard working spaces to
the white/gray balanced file in Photoshop. Neither of these approaches
will be quite as good as using a VERY good "custom" profile for the 16
bit "raw" data file but both of these approaches are much more practical
for the vast majority of images you need to capture.

Regarding custom profiles for lighting situations:

It seems to me it would be better to shoot a color target each
time and use that to generate a source profile on the fly
(I assume there is software that could do this without manual
intervention).
It seems to me that this would be far more trouble than it is worth
because to my knowledge there is no software that can do this without
some kind of manual intervention and there are plenty of times when you
simply can't shoot a target. The benefits are not great enough to
warrant the extra trouble either - it is expensive and time consuming to
get a custom profile that would be better than simply assigning a
workspace to a white/gray balanced file for even 50% of the subject
matter you are likely to photograph.

...my question was whether one profile is correct for all
lighting conditions.
Nothing can possibly be "correct" for all lighting conditions. Even if
you white balance every shot you can screw up the color because there is
always an emotional component that can never be fully accounted for. For
instance, if you manually white balance a sunset scene you will "balance
out" the overall red color and completely destroy the feeling of the
sunset in the image. It is the same thing with profiles. If you apply
ANY automatic color compensation scheme you are bound to generate a
majority of mediocre images unless you ALSO apply some intelligent
interpretation along with that automatic "correction". We can expect to
get good color right out of the camera but mostly, even with film, we
simply get what we get and call it good or adjust it in some way after
the fact. I think the challenge for photographers or anyone dealing with
digital photographic images is to create great images by interpreting
color in the most emotionally satisfying way. With all the controls we
can exert digitally we should not have to stop at "pretty close" nor
should we have to agonize over what the "correct" color is. Experience
working with Photoshop's color controls can make the task of generating
GOOD color relatively easy and painless especially with images that we
capture digitally.

--
regards,

Lee Varis
varis@varis.com
www.varis.com
888-964-0024

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