Graphics Programs Reference
In-Depth Information
you save and archive that data, especially if you decide to convert directly
into an RGB working space.
Most of the high-end packages that control the process of capture and
conversion actually embed an ICC profile into the resulting files they
create instead of EXIF data seen mostly with DSLR products. Virtually all
these products produce conversions into a working space using source
and destination profiles and do so using any profiles installed on the
user's computer. Some DSLRs allow a user to shoot a RAW file plus a
JPEG file at the same time. The secondary JPEG file can be useful since
a JPEG is usually adequate for quick viewing, editing, and creation of
proof sheets or upload to a web page. The settings for producing color
conversions from RAW to JPEG have no effect on the RAW data. The his-
tograms seen on the LCD of these cameras are not based on the RAW
data but in most cases, the converted RGB data or luminance data, based
upon whatever matrix (color space) the user sets on the camera.
When Camera Profiles Go Bad
In most cases, when a camera profile fails, it's obvious after it is assigned
to the image. You usually will see severe aliasing and posterization or
areas of color that are clearly not the correct appearance. When a profile
isn't producing the quality it should, sometimes you will see abrupt tonal
transitions or areas that show what appears to be excessive noise. It is
quite alarming to see and at the same time, interesting how simply assign-
ing a poorly made profile can produce such ghastly color appearance.
When a profile is working as it should, you should see a noticeable
improvement when you assign the profile to the captured data. If that is
the case but you still want to evaluate the quality of the profile, use the
same guidelines discussed in Chapter 4, covering scanner profiles. Also,
note that editing the camera target image to adjust a resulting camera
profile can work as it did with the scanner target.
As discussed in Chapter 4, you can apply the opposite edit to the
camera target to produce a desired result in the camera profile built from
that camera target. Additionally, you can improve the captured target
image with careful image editing, for example, if you wanted to even out
the lighting across the target for better results. I have built simple grad-
uated masks in Photoshop to apply small levels correction to ensure all
four corners of a target have the same luminance values. This seems to
work well with some profiling packages, but do this only as a last resort.
If you find yourself in a situation whereby you simply can't produce an
acceptable camera profile, investigate other RAW converters or simply
give up, as many have, and process the data using something like
Adobe
Camera RAW
. This product doesn't require you to deal with camera pro-
files. If you are working with images that are being automatically
processed into a standard matrix (color space), you can tweak the effect
to a small degree by building a simple matrix profile using Photoshop.
