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I'm running 14.04 on a Sony Vaio VPCF13Z0E which has a NVIDIA® GeForce® GT 425M GPU card, and have both Gnome colour manager and dispcalGUI installed. I've a Colorhug which runs from the liveUSB but I cannot fathom how I adjust the red/blue/green when I start measuring to calibrate. Brightness I can adjust, contrast too. But no amount of digging has found a way to adjust those 3 colours by themselves.

I can't do the basic calibration from settings>color either; the calibrate button is greyed out. It also won't let me add or import profiles either, or let me look at the settings, which is something I can do whilst running the live USB. This is a problem I think with the Colorhug, as it's not recognised when running Ubuntu despite having the software installed.

I've tried to find the answer in relation to dispcalGUI but all I seem to find is "then adjust the colours..." with no explanation of how! I'm assuming this is because Gnome colour manager isn't working? Or is there something else very simple that I've missed?

I can't adjust the red/green/blue on either Ubuntu or on the liveUSB that came with the Colorhug, although it will let me do a basic calibration via settings>colours on the liveUSB.

Everything that's supposed to be installed is installed, and it feels like I'm going round in circles...any help appreciated.

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But no amount of digging has found a way to adjust those 3 colours by themselves.

On a Laptop, you can't - the screen needs to have the necessary hardware controls, and Laptops lack these. You should skip this part of calibration on a Laptop (the "Laptop" preset does this too if you select it).

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  • well, yes - a laptop doesn't have the necessary buttons, but surely with a dedicated graphics card that should be a software issue? – Woolly Wormhead Aug 10 '16 at 8:44
  • @Woolly Wormhead: Software solutions (including calibration tools like Argyll's dispcal) need exclusive access to the video card gamma table, because that is the only way to adjust RGB balance globally when the display itself doesn't have hardware controls. So, it's a either-or situation: Let the calibration tool adjust the video card gamma table, or use another tool (like nVidia Settings or the like) to adjust RGB balance, but not both. – Florian Höch Oct 17 '16 at 22:00
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This may seem obvious, but you need a calibration device attached to the system to activate the calibrate button under System Settings- Color

As far as calibrating the Colorhug device goes, Options are limited:

1) You could use an available calibration matrix. There are a number of laptops listed here. The file should match your model exactly. If your laptop isn't listed and/or you want to check the latest info, you might benefit from joining the color-hug users group to trade experiences and information

It looks like you can utilize one with

colorhug-cmd set-calibration-ccmx 0 calibration.ccmx where calibration.ccmx is the calibration file you downloaded.

2) If option 1 doesn't work for you, You could create your own calibration matrix.

To factory calibrate the ColorHug you need a photo-spectrometer, e.g. a ColorMunki (you can likely rent one fairly reasonably and the xcalib software installed.

Ensure your screen has been turned on for at least 30 minutes. Calculating the dark offsets

Place the ColorHug on a black dark surface and press down to ensure no light leaks into the aperture. Do a raw measurement using:

colorhug-cmd set-dark-offsets 0 0 0 xset dpms force off && sleep 5 && colorhug-cmd take-readings && xset dpms force on R:0.0002 G:0.0001 B:0.0001

These can then be programmed into the ColorHug using:

colorhug-cmd set-dark-offsets 0.0002 0.0001 0.0001
colorhug-cmd write-eeprom "Un1c0rn2"

Working out the calibration matrix

We first generate a ti1 file containing a list of patches to measure:

targen -d3 patches

Then we measure the patches using the photospectrometer which creates a ti3 file from the ti1 file. For this bit you have to attach your photospectrometer to the computer and disconnect the ColorHug. Note, you need to use the -s flag to ensure that the spectral data is saved.

dispread -d2 -yl -s patches
mv patches.ti3 colormunki-hp-lp240zx-srgb.ti3

Then we measure the rest. Reset the screen and device to default, and measure the spectral response using the ColorHug. So, remove the photospectrometer and attach the ColorHug.

xcalib -c
colorhug-cmd set-calibration-map 0 0 0 0 0 0
colorhug-cmd set-calibration-ccmx 0 unity.ccmx
colorhug-cmd write-eeprom "Un1c0rn2"

dispread -d2 -yl patches
mv patches.ti3 calibration.ti3

With the two .ti3 files, we can generate a colorimeter calibration matrix:

export ccxx_desc="Factory-Calibration"
export ccxx_ref="colormunki-hp-lp240zx-srgb.ti3"
export ccxx_src="calibration.ti3"
export ccxx_mat="calibration.ccmx"
ccxxmake -I $ccxx_desc -T LCD -D$ccxx_desc -f $ccxx_ref,$ccxx_src $ccxx_mat
colorhug-cmd set-calibration-ccmx 0 calibration.ccmx

3) If you don't have access to a photo-spectrometer, then you can use the display EDID to generate a CCMX from it. This is done automatically if you use DisplayCAL and set measurement mode to "Auto" (only available for the CH1 and CH2).

Sources:

http://www.hughski.com/calibrate-coldplug.html

https://www.mankier.com/1/colorhug-cmd

https://www.mankier.com/1/colorhug-ccmx

https://groups.google.com/d/msg/colorhug-users/FeGflzzXhOc/GBGP6XzPAwAJ

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