Re: profiling monitor range
Re: profiling monitor range
On Jun 19, 2006, at 12:05 AM, Graeme Gill wrote:
Unfortunately, the CRT calibration routines can not accurately
describe the slope of multiple contrasts in the LCD/TFT.
Care to translate that statement into something meaningful ?
What is "slope of multiple contrasts" ?
Sure. Whether LCD or TFT, the technology does not exhibit a single
curve (or more accurately stated, straight line) over the entire
brightness range, as the analog CRT device might. Instead, one finds
various issues in the highlight, midtone, and shadow regions which
force the calibration software to manage not only the independent
issues, but then also the resulting approximation of a single curve.
The failures of the system in producing a good black and smooth
transitions through the shadow region are especially difficult to
overcome . . . unless sophisticated LUT functions can be employed.
linearization, you might better appreciate the L* concept for
monitor contrast. . . and how it is more neutral plus offers more
accuracy in producing equal steps of brightness changes throughout
the contrast slope.
Sorry, I don't see and particular connection between the calibration
target luminance curve (be it a power curve, a power curve
with a flat region near black, or an L* shaped curve), and
the neutrality of the resulting curve for equal valued RGB input.
They are orthogonal axes, hence independent.
Let's assume that uniform perceptual RGB contrast is a gamma of 2.46,
and is approximately equal to uniform L contrast. Let's further
assume that with a* and b* equal to 0 each, that the perception is
absolute neutrality.
If that is the case, and if we are trying to dig contrast out of the
flat panel shadows, while constraining contrast in other areas, then
the best chance of a monitor matching a printed piece (and the
correlating gradations) would be to delicately manage the various
display issues in a way that is transparent to the end user (no pun
intended).
In simple terms, flat panel calibration is extremely difficult, by
comparison to CRT calibration - and matching a flat panel to a
printed piece (when judged by neutrality and contrast) is one of the
hardest functions to accomplish. basICColor display has done an
excellent job of the calibration and profiling of flat panel displays.
- Jon
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