Graphics Programs Reference
In-Depth Information
should be given a good 30 to 45 minutes after being turned on to assure
color critical viewing.
Both technologies have advantages and disadvantages. LCDs appear
to produce a sharper, flicker-free image and thus many users find they
can edit images longer with less eyestrain. LCDs generally produce more
luminance, thus the need for low ambient light conditions is less an issue.
However, CRTs can generate higher contrast ratios. The bad news is that
LCDs have a fairly significant problem when it comes to viewing angles.
As you move your head from side to side, the appearance of color
changes. This is one of the biggest problems I have with LCDs for color
critical work. CRTs don't present this issue. LCDs have few options for
physical adjustment. Most offer only a backlight control. Many LCDs' on-
screen controls (OSD) offer other adjustments; however, these are often
only software adjustments and not actual physical controls. Many CRTs
have controls over the RGB amplifiers as well as separate controls for
both black level and luminance.
There are two ways to calibrate a display. One is to alter the display's
behavior using controls that physically affect the signal. The other is to
alter the numbers of image data inside the graphic card. To do this we
modify the graphic card LUT or CLUT (Color Look-up Table; see the
sidebar, “Calibration for LCD and CRT”). In Chapter 1 we discussed
gamma. Recall that the use of a Look-up table can create banding or alias-
ing artifacts in images. Physically calibrating a display does not cause this
problem.
My personal opinion is that LCDs are great for all types of general
Photoshop and retouching work, but not the best option for those that
need critical color. CRTs, especially those high-end
smart monitors
I will
discuss later, provide the very best solution for accurately viewing images.
I usually recommend users have at least one CRT for the areas of critical
color of the pipeline. LCDs are getting better and I suspect that new
technologies that address some of the issues, especially viewing angle
deficiencies, will come about in the foreseeable future. At least one man-
ufacturer, Eizo, has produced an LCD that attempts to improve the quality
and accuracy of color images. CRT displays are not a technology most
of us will be using in five years. The manufacturer of high-end CRT
tubes will cease as there are not enough buyers to maintain production.
The average life span of a CRT display when properly calibrated is about
three years. The fluorescent tubes in LCDs also degrade, but may have a
longer life span. Some third-parties can replace these tubes but the cost
may be prohibitive.
Calibration, Then Profiling
In the first chapter I discussed the differences between calibration and
profiling. Display systems require that we calibrate them to a known con-
dition and then profile that behavior. Since display systems are some-
