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|Sep 21, 2002, 9:40 PM||#1|
Join Date: Jun 2002
Grrr! I hate color management. Could anyone tell me what I'm doing wrong? I bring one of my daughter's wedding pics into Elements ( a copy, originals are burned to a cd) and use Levels, Color Cast Correction (outdoor wedding with greenish cast from the surrounding foliage), and a Pictographic plug in to correct skin tones. Ah, perfection. I save as a TIFF and this is where the problem occurs. If I save without checking the ICC Profile embedding it's the same. If I add the ICC embedding, it gives the images a noticeable warmer tone, or increased saturation, with orange skin tones that are objectionable. I'm using a Toshiba laptop with LCD screen, used Adobe Gamma and loaded AdobeRGB1998 profile (sRGB came loaded by default, but it does the same thing as the other). I plan to upload the images to dotphoto.com so everyone can order prints, so I thought I should embedd the ICC profile, but this ruins the images. Any help understanding what I'm missing would be immensely appreciated. Thanks a bunch. Awesome job on this forum, Steve. It's my favorite place in the world these days. Jeff
|Oct 11, 2002, 10:42 AM||#2|
Join Date: Oct 2002
this is part of an artikel i've read before, it might help y
Color correction and color management is one of the most important and difficult areas in digital
photography. We are not experts on this subject. We want to share what we have learned and invite all
who know better to correct our faults and improve this chapter for the use of all interested in this subject.
If you have a photo on the web and different people discuss the quality of the colors of a photo they most
of the time have the following problem:
· Different monitors show the same RGB value quite differently
So besides there many opinions o n color they actually see different versions of the same photo.
But the real challenge is to get the right impression on a monitor how a certain photo would print on a
color printer. The new inkjet printers from Epson (HP, ..) can produce amazing results. But without color
management it remains trial and error. You end up to change the color settings of the printer for every
print without very much being satisfied. So what does color management mean? In our example it means
that the photo you see on the monitor looks very close to the result you get from your printer. This is
called "soft proofing". With very costly monitors the match can be very close.
The reason for this dilemma is that every device: monitor, printer, scanner and digital camera has very
different capabilities to render colors. If there is a fixed RGB value the display of that value on that device
will be different and certain values the device might might not be even capable to render. The colors a
specific device can render describe a gamut of colors. Color management is based on a standardized
description of that device (so called ICC profiles). You either get these profiles from the device
manufacturer or measure it with special calibration hardware.
As most people like to use there monitor as there "soft" proofing device. That is why the first step towards
a color management is the calibration of the monitor. Be aware that very precise calibration also is
influenced by the room and even your clothes. Adobe Photoshop comes with a utility called Adobe Gamma
which lets you calibrate your monitor. Although this is much better than not doing any calibration at all it
is better to use some hardware calibration device. We uses different tools like Optical/X-Rite,
Optical/Spyder or GretagMacbeth Eye-One. To do the calibration just follow the instructions of your tool.
The monitor should be on for more than 30 minutes and don't change any monitor settings without any re -
calibration, a re -calibration is anyway recommended about once a month.
Profiling LCD monitors can very tricky and the success depends on the tool and the monitor brand. We use
a LCD monitor not because it is the best proofing device but we think it helps with our eyesight as we are
also writing a lot using the same monitor.
How to find our which monitor profile Photoshop is using:
Select "Edit->Color Settings" and use the drop down list where you can select working spaces and scroll
(mostly up) till you find the entry "Monitor RGB" (above shows Sony_LCD_std_D50). This entry shows the
monitor profile which gets used. Then "cancel" the "Color Settings" dialog so that you do not change your
Let's see where we are:
We have some RGB values of the image (YMCK is excluded from this discussion as we only work in RGB).
These values are mapped to the monitor using some monitor profile and also mapped to the printer by
using a printer profile. This would probably work for this close loop. But what if you send the image file to
an other person. He would need your monitor profile and then map it to his monitor profile (which is
certainly different). You might envision that this would not work in the real world. Up to this point we have
only discussed about profiles for individual concrete devices. The ICC solution for this dilemma is the
introduction of abstract standardized color profiles/spaces (e.g. Adobe RGB (1968), sRGB, Apple RGB, ...).
These are very well defined profiles which might not match any device in the world. The solution is now as
follows (we assume the color space Adobe RGB -this is the one we use). The image internally stores all
RGB value in relation to the internal (abstract) color space (here Adobe RGB). Photoshop's ICC engine now
translates all these RGB values from the internal space to the concrete monitor space (using a monitor
profile). The same happens when you print.
Now sending the image to an other person is no problem as the same happens there again. The
information about the profile is stored by Photoshop (also other applications like Bibble, Qimage,...) within
the image (TIFF, JPEG). The abstract standardized color spaces range from a narrow gamut to broader
gamut. It is quit obvious that if you image is working with a narrow gamut that some colors get lost as a
transformation which broadens the gamut has to "invent" missing colors and that is not possible. If the
gamut is to wide you deal with colors which probably none of your target devices will ever be capable of
**** Some Standard Color Spaces
The following table discusses some of the most important abstract color spaces:
NTSC This is the space for the US television. It is even worse than the
European PAL standard. It is presented here that some believe the
Nikon D1 uses this space to create the non RAW/NEF files. It looks as if
that is not a very good choice. As I understand this is not an issue for
This space is still pretty narrow but is supported by some printers
(Epson 1270) and scanners (Nikon LS 2000). It might be a good idea to
use this for photos on the WEB.
Adobe RGB (1998) This is a very popular space among Photoshop users. It covers most
printable colors. This is what I use.
Pro Photo RGB Colorspace supported by Kodak (wide gamut)
Apple RGB Not as wide as AdobeRGB
Bruce RGB A space designed by Bruce Fraser which is a bit wider than the Adobe
**** Monitor Profiles
By now it should be clear that all goo d color management starts with a good as possible monitor profile.
**** Camera Profiles
Also profiles for you camera are very important. We will discuss this later in the chapter "Raw File
Processing". There are two types of profiles: Camera Generic (used by most RAW conversion tools) and
specific profiles for certain light conditions. This is an important distinction as for an optimal profile all the
parameter have to be constant (light, RAW processing options, exposure)
*** Printer Profiles
There is actually no profile for a printer. The profile is always for one paper, the same ink, the same
individual printer and the same printer driver used. Profiles for different papers can vary significantly.
We will talk about printer profiling in more detail in our chapter about "Printing".
**** The important image formats
TIFF This is the standard high quality image format without any loss. It
comes in 8 and 16 bit versions
Important standard compressed file format. There is a quality loss
even at low compression levels. Mostly used for the web or
transmission over slow connections.
JPG 2000 Newer improved version of JPG. Not widely used yet
STN Storage Format of Genuine Fractals for use in image upsizing (see
PSD Photoshop format which allows to store some internal information
(like layers) with a file. Can be useful for intermediate files.
GIF For Web usage as there are only 256 colors available
NEF Nikon RAW image format (compressed and uncompressed)
CRW Canon RAW image format
other RAW formats There are also RAW formats from Kodak and Olympus
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