Re: Printing of photography
Re: Printing of photography
- Subject: Re: Printing of photography
- From: David Ramsey <email@hidden>
- Date: Mon, 20 Dec 2010 12:05:21 -0500
So, If I do include a color target and I, for example, move the blues
towards purple is this not going to throw whomever is looking at he
image off. It seems that if the printer is trying to "match" a target
then he/she will be incorrectly "correcting" the artwork. This leads
me to this question, If I am in a color managed workflow (my
responsibility to be accurate) and I send you or whomever an RGB
ADOBE98 file tagged as such and you open the file on your color
managed system (your responsibility to be accurate) would you not see
the exact same thing as I do? And likewise, should the printer see the
same?
I am not comfortable sending special instructions downstream with a
file. Who knows where or with who it is going to land.
David Ramsey
On Dec 20, 2010, at 11:40 AM, Robert Rock wrote:
I could not disagree more with Ken's suggestion that NO color target
should
be used when photographing artwork. In my opinion, there absolutely
SHOULD
be some known reference included in the photograph, perhaps a Macbeth
ColorChecker, or even an old Kodak Q-13 chart. Assuming that the
image will
be reproduced from this digital capture later on, what would pre-
press or
the printer use for a reference? You have to assume that they have
never
seen the image and have no idea what it should look like. Instead of
wasting
everyone's time sending proofs back and forth, it at least gives
them a
visual reference that they are in the ballpark when proofing. Ken is
right
that there are some issues that may affect color accuracy (metamerism,
etc...), but there still needs to be a base from which to start. The
printer
or pre-press person needs to have some reference as to what the
image should
look like. If there are no color bars or reference data in the
image, the
first thing the printer will tell you before proofing is that 'he
has no
idea what the image should look like and that all he did was output to
proof...'. After proofing, if further color tweaking and adjustments
are
desired to more accurately match the original, then have at it.
There most
certainly WILL be the need for tweaking of the color and/or tonal
contrast,
if not for reasons that Ken mentioned, perhaps because of the inks
used,
paper, type of dot pattern, etc...But again, I believe that there
should be
a starting point or reference for the printer, and that should be
dictated
by the use of a known color reference included in the capture. One
can agree
or disagree with this, but bottom line is that 1) Many printers WILL
require
it, and 2) What harm does it do to include it in the capture? You
can always
give the instructions to ignore the patch if you so desire.
Bob Rock
-----Original Message-----
From: colorsync-users-bounces+rock=email@hidden
[mailto:colorsync-users-bounces+rock=email@hidden]
On Behalf
Of Ken Fleisher
Sent: Monday, December 20, 2010 10:10 AM
To: David Ramsey; ColorSync Users Mailing List
Subject: Re: Printing of photography
On Mon, Dec 20, 2010 at 9:18 AM, David Ramsey
<email@hidden> wrote:
2 questions;
1) I am getting ready to photograph some works on paper for a museum
and I was asked about including "color bars" in the photos. Because
of
the nature of the materials used in these works I have to adjust
specific colors as we shoot (Color managed workflow and calibrated
display). Colors are adjusted individually, for example, purples
may go
towards blue reds towards magenta.
So if I place color bars in the frame and will this not create havoc
down the line since I am moving individual colors around? Also which
color bars should I use if they are to be included?
I do not recommend including a color target when photographing
artwork for
reproduction for the following reasons:
1. The camera's spectral sensitivities are different from a human's.
Because of this, the differences in the material on a color target
and the
artwork can result in "observer" metamerism. (i.e. getting the color
of the
target correct does not imply that the color of the artwork is
correct.)
2. Because of observer metamerism, the color target is not a reliable
indicator of an accurate color capture of the artwork.
3. As you describe, if you make color edits to the image to make the
artwork
correct, the colors on the target can no longer be used as a
reference of
any sort, since those colors will necessarily be moved as well.
4. Trying to match the colorimetry of target colors all the way to the
printed page is an incorrect goal anyhow. If you do this, your
reproductions
might be colorimetrically correct (if you are lucky), but will
likely appear
dark and flat. Instead, you must try to match the color appearance,
which
usually involves opening up the image and increasing contrast (many
perceptual rendering intents achieve this for us when printing, but
not so
for image capture).
I recently spoke on this very topic at "Currentl Practices in Fine Art
Reproduction" which was a symposium at the Rochester Institute of
Technology. You can view a video of the talk at
<http://tinyurl.com/3x5rv6v>. This was a panel discussion on target-
based
workflows and my part begins at 29 minutes into the video (though
you may
find the entire panel interesting.).
Ken Fleisher
Color Scientist
National Gallery of Art, Washington, D.C.
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