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LPROF is an open source application that creates ICC profile for cameras, scanners and monitors.
LPROF can work in two
different modes to generate a monitor profile. The "advanced" mode, that gives accurate
profiles by using hardware devices like X-Rite DP92 or EyeOne,
and the "simple" mode, that allow to you build reasonably accurate
profiles without any additional hardware.
Let's build our first monitor profile to check how all this
stuff works. We don't need great accuracy at this point. We want to
calibrate coarsely, just to visually check if all is going OK. First start LPROF. Since we
need only a coarse profile on the "Monitor Profiler"
tab select the radio button labeled: "I want to build a coarse profile,
giving approximate values". This is selected by default. We
do not need any hardware measurements at this point only a few visual
adjustments. Press the button labeled: "Enter monitor values". You will see
the monitor values dialog.
In order to obtain maximum
performance, we need to adjust the physical monitor
Set contrast to near maximum, (yes, near maximum. This is the
gain of monitor and we need as much gain as monitor can deliver).
Now select the "Set Gamma and Black Point" button. This dialog will help you to set both the gamma and black point for your monitor.
For information on setting monitor White Point see Rough Monitor Values.
Now you can use the "Profile Identification" dialog to fill in the info about your monitor. Although this is not strictly required, it could prevent a lot of confusion when you have more than a couple of profiles. Now we are ready to generate our profile. We must specify the output filename just like you did when creating a scanner/camera profile. For the name, we could use "CoarseMonitor.icm" So, type in the name and then proceed to generate the profile by pressing the "Create Profile" button. If all is OK, the status console will show "Profile DONE!" Let's now check how well the profile is working by eye. Do this is basically the same way you proofed your scanner profile above.
To measure your monitor, you need to create a IT8 sheet
measurements for several RGB combinations for your monitor. A
sample sheet of this kind can be found in "data/pics" directory. The
called "sRGB.IT8" and it measures an ideal sRGB monitor. Use this file
as a template for creating your own monitor measurement sheet. You need
change the XYZ values to those read by your measurement device. Don't
put any Lab value, just RGB and XYZ. Please keep the RGB values the
sRGB.IT8 has. Optionally, you can use more patches to assure consistent
color reproduction, but make sure to include at least the ones in
sRGB.IT8. In the "data/pics" directory you will also find
"monitor patches.tiff". This file contains color patches that
correspond to the values used in sRGB.IT8 and it can be used to measure
the RGB values from your monitor. Note that a large number of
gray patches are needed. You can also add as many as you wish, with
more gray patches, you will get better linearization control curves.
You must specify at least 16 gray patches.
Now we will try this procedure, if you do not have a measurement hardware device you can use sRGB.IT8. We are going to generate a sRGB profile, by using the sRGB.IT8 measurement sheet. Go to the "Monitor Profiler" tab. Now, we are going to use it in advanced mode. Select the radio button labeled: "I want to build accurate profile from measurement sheet". Then press the "..." button located at right of the edit box labeled "Measurement Sheet". Select in "data/pics" directory the file called "sRGB.IT8". In the "Output profile file", select a new file name for your profile. Call it "my_sRGB.icm". I will use this sample to present another utility, the profile checker. Since the profile checker can understand advanced tags, we want to include all information in the profile, so select the "Profile Parameters" button, and make sure to select "Verbose, store anything" in the "profile verbosity level" group. Now use the "Profile Indetification" button and fill the info fields if you want (again, this is recommended) and press then press the "Create Profile" button. A new "my_srgb.icm" profile will be created. We will check now how accurate this profile is. Start the profile checker dialog selecting the "Profile Checker" button. The profile checker is a tool for inspecting some of profiles internals. In our case, we want to check the accuracy.
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