Re: Color spaces/ Digital Cameras
Re: Color spaces/ Digital Cameras
- Subject: Re: Color spaces/ Digital Cameras
- From: Paul Guba <email@hidden>
- Date: Thu, 31 Jan 2002 11:07:48 -0500
As a photographer my feelings about digital camera imaging are not to
different from using film. There a several key thing that must be
considered. First off, exposure as it changes so will my color this is
the same for film as for digital imaging. Quality of light, contrast or
the lack of. This does not effect color but rather the appearance of
the color in the given picture. Color temperature of the light source,
this will have an effect on how color is recorded. These all apply if
digital or film. Now when I shot more film I would buy a large amount
and test it in some controlled way. Much the same as creating a camera
profile although I believe profiling to be a better method. This gives
me a foundation from which I can build. If things change either in my
control or not, at least I have a consistent starting point that I
believe to be valid.
You have no consistent starting point it is out of your control. Its
like not knowing what kind of film you are about to process. It has
little to do with ICC profiles or the gamma of some camera's front or
back end. It is simply a lack of knowledge on your part. As a
service provider you must some how regain this. It may mean requiring
your clients to tag images and educating them how to prepare their
images for your output. It may mean you have to manually look at each
image and make adjustments. Your in house is fine because you have
control so I will assume that it is calibrated in some manner. Control
and being consistent are the key to good repeatable reproduction of
color.
For an image that has an unknown color space I could guess at what it
is. I prefer to open and assign my working space. If it looks
acceptable than I will convert to my printers space and print.
Otherwise I will need to correct it till it is acceptable. It would be
no different if I made a C print. I would have starting point but I can
make changes from there if needed. Its the most you can expect in an
uncontrolled situation. If the image is uncorrectable than thats
another issue.
On S-curve
Indeed film does have the characteristic S-curve some more than others.
However you say you are scanning film and making fine prints. Am I to
assume that this characteristic magically goes away when you scan. No
because photographers compensate for this by proper exposure. Placing
most of the image on the flat portion of the curve. Now a good scan can
compensate for data on the edges but it cannot replace what is not
there. Digital cameras were designed to mimic the S-curve because so
much traditional processes were in place with that curve. So it was
easier to emulate it rather than reinvent the wheel. The data should be
similar from either though. So I cannot believe that this is your issue
rather not knowing what curve you are getting.
It is difficult to give you a solution because I do not know your
clients. If they are Joe Anybody off the street than you will continue
to have issues unless some standard is in place. If they are
photographers and artist than you can expect more from them and should.
Good Luck
P Guba