Calibrating and profiling a monitor is something I don’t like doing. So I’ve used the same profiling process for a long time. But recently I’ve been experimenting with various ways to calibrate and profile my monitor and discovered (well, this surely isn’t news to most people!) that way the profile is made fairly radically affects deep shadow tonality as displayed on the screen.
Here are two “xicclu” curves, from two profiles made using Argyllcms. Both profiles use a calibration file to create a neutral gray axis. Actually both profiles use the same calibration file. Both profiles are shaper matrix profiles. Similar xicclu curves result from using Displaycal, depending on the parameters used to profile the monitor:
The xicclu curve on the left is from a calibration+profile done in one step using just the colprof utility. I requested a gamma=2.16 TRC for the calibration file as this gamma is roughly the “native” gamma for my monitor, so requires less correction to get a neutral gray axis.
The curve on the right uses the same calibration file as the curve on the left, but was done in several steps using targen, dispread, and colprof.
Notice that where the two curves reach the x-axis, the left curve is almost a 45-degree straight line, and the right curve has a pronounced downward hook.
The xicclu curve on the right resembles the xicclu curves for the monitor profiles I’ve used until recently. The presence or absence of the downward hook makes a huge difference in the deep shadow tonality:
In Firefox, which doesn’t allow for black point compensation, the following image has totally crushed shadows if I use the monitor profile with the xicclu curve shown on the left. But the shadows aren’t crushed if I use the monitor profile with the xicclu curve shown on the right.
In GIMP, using the monitor profile for the xicclu curve on left with black point compensation, makes the image look very close to how the image looks using the monitor profile for the xicclu curve on the right, when black point compensation is not enabled.
Actually, as surrounded by white on the pixls webste, the shadows in the image look crushed no matter what, so the same image is on this page, about the fourth image down: Pictures in progress
As the point of putting an image on the web is so other people can look at it, I wanted to ask a couple of questions:
Does image above have completely crushed shadows when viewed on your monitor?
Whether yes or no, what does your monitor’s xicclu curve look like? Here’s the command to ask xicclu to draw the curve:
xicclu -ir -fif -g nec-20171216-1242-as-qh.icc
At least on Gentoo, you have to write this instead, unless you downloaded ArgyllCMS from the argyllcms.com website and put the executables in /usr/local/bin:
argyll-xicclu -ir -fif -g nec-20171216-1242-as-qh.icc