Graphics Programs Reference
In-Depth Information
ties of each user's display. They also realized that working in a device-
independent color space like LAB presented many problems for users. In
order to accomplish this, Adobe had to make a number of radical changes
that had never been attempted in an image editing application.
A Divorce of the Display
The first change to Photoshop 5.0 (and all versions since) was to divorce
the specifics of a display from the editing of our images. The goal was for
two users with the same document, and thus the same set of numbers,
to see the same color appearance on their own displays. Users could be
encouraged to use very expensive hardware to calibrate their displays but
even after this process, display systems are so different from one another
that color matching could not be assured. In addition, the gamut and
properties of the editing space would be dependent on the display, and
there were many instances where a wider (or narrower) color gamut
would be useful for some.
Forcing an editing space based upon the properties of a display would
limit many editing and printing options. In addition, different users on
different computers would be calibrating to different Tone Response
Curves (gamma) so the same numbers would be displayed differently.
The solution would allow Photoshop to deal with numbers in such a way
that the characteristics of the display could be removed from the assump-
tion of the image data. Rather than send numbers in our document
directly to the display, Adobe implemented a system that bypassed this
direct viewing mode. The first step necessary to allow Photoshop to sep-
arate how we edit our documents from the display is to calibrate the
display and create an ICC profile reflecting the condition of that unique
display's behavior.
Due to cost factors back in 1998, few users could calibrate their display
using hardware to set the display into a known condition and create an
ICC profile reflecting that behavior. Realizing that most of Photoshop
users didn't have such devices, Adobe shipped Photoshop 5.0 with a
utility called Adobe Gamma,
1
which allowed the user to
visually
calibrate
and create an ICC profile for that display. Although this approach is not
as accurate as hardware calibration, it was a step in the right direction.
Users of Adobe Photoshop 5.0 and later needed to utilize either Adobe
Gamma or a hardware calibration device to create the ICC profile that
reflects the current state of the calibrated display. This profile allows mul-
tiple users who calibrate their display to view documents in Photoshop
identically, despite platform or specific display hardware.
1
Prior to Adobe Photoshop 5.0, Adobe supplied a product to adjust the screen
using simple sliders called Knoll Gamma. This product was abandoned since its
purpose was to alter the display color to match a printed reference and the
product didn't actually calibrate or create an ICC profile.
