[Scribus] [OT] Color management - profile for my monitor?

Hal V. Engel hvengel
Sat Oct 21 20:55:28 CEST 2006

On Saturday 21 October 2006 10:29, Craig Ringer wrote:
> Plinnell wrote:
> > On Saturday 21 October 2006 17:11, Philipp Klaus Krause wrote:
> >> I have a Belinea 10 19 10. The documentation claims it can do
> >> 6500K, 9300K, "User" and "sRGB", but not 5500K.
> >> The on screen menu offers choices: "warm", "cold" or selecting RGB
> >> values on a scale from 0 to 100 for each color. There is no
> >> information in the manual about how these relate to color
> >> temperatures, Belinea didn't answear when I emailed them about it.
> That's rather odd. Many monitor OSDs offer temperature settings
> separately to the main colour section, so do look around the whole OSD
> menu. Failing that, I don't personally know of a reliable way to set a
> monitor's colour temperature. (For that matter, I wouldn't be surprised
> if many monitors' settings, especially LCDs, were a long way from
> accurate anyway).
> > Warm more than likely = 6500K and Cold = 9300K (usual default)
> Warm could easily by 7200K or similar as well, that's not at all uncommon.

The controls on monitors vary as to what they do and what they actually allow 
you to set and how close those settings are to what the actual result is on 
the monitor.  My stepson has a Dell 21 inch monitor that uses the Sony 
Trinitron tube.   With this monitor it is only possible to set it to four 
color temperature presets (IE. you can't set the gain for the individual RGB 
guns).  These color temp. presets are labeled 5000K, 6500K, 7200K and 9300K.  
When calibrating this monitor using a GretagMacbeth EyeOne Display LT and the 
supplied software it turns out that the 5000K setting is actually very close 
to 6500K (I think is was actually 6400K which is definitely good enough).  So 
the presets are off by about 1400K.  By the way being off by 1000K will 
result in an average delta E of about 3 and a max delta E of about 12.  
Getting an average delta E of 3 on a monitor is considered to be a fairly 
good setup.  So being off by 1000K is not a big deal but anything more than 
that is too much.   If all you have are these type of presets about the most 
you can do without a measurement device is select the one that is closest to 
your desired color temperature.  But in the case of my stepsons monitor 
setting it to 6500K would have resulted in a color temp. closer to 7700K 
which is too cold.

By the way for most users 6500K is what you should be trying to get.

My monitors on the other hand have not only the preset color temperatures but 
also the ability to set the individual RGB values for the guns.  This is on a 
0 to 100 scale just like the OPs monitor.  But individually setting the RGB 
gain for the guns without a measurement device is just not a workable 
solution and I recommend that you not even try this.  Use a warmer preset and 
you will at least be in the right ball park if the monitor does not have a 
major problem.  With a measurement device you can get the color temperature 
very close to being correct if the monitor does not have any hardware issues 
(typically +-25K).

The other issue that affects this is room lighting (adapted viewing conditions 
in color science speak).  Your room should be somewhat dim and the over all 
color temp. of the lighting should be about 5000K.  Most light bulbs are much 
warmer than this.  For example incandescent bulbs are closer to 2800K and 
typical compact florescent lamps are around 3200K.  In addition the color of 
a rooms walls and other objects in the room affects this and one way to 
compensate for warm light sources is to paint your rooms walls a cool color 
such as blue.  But for best results work is a room with neutral walls and 
using a light source close to 5000K.  If you use warmer light sources then 
colors on the monitor will appear cooler than they actually are.

> > You can try the 6500K profile, but it may or may not work well. Martia
> > Maria of littlecms has told us not all manufacturer provided profiles
> > are useful and some are broken. There is a fair amount
> > of 'self-defense' code in Scribus and littlecms to handle incorrect
> > or broken profiles.
> If the manufacturer's supplied profiles aren't just broken, then they're
> probably better than what you could make "by eye," but you'd be sure to
> get a better result from a calibration device if you have access to one.
> Of course, if you're working under Linux calibration devices aren't
> presently easy to come by :-(

One possible Linux solution is to use ArgyllCMS with the X-Rite DTP-94.  
Support for the DTP-94 was added in the latest version of ArgyllCMS and this 
will work on Windows, Mac and Linux/Unix OSs.  The DTP-94 is about a $200 
instrument in the US.  All of the other instruments supported by ArgyllCMS 
are significantly more expensive or are older and difficult to find.

If you are working in Windows or the Mac the least expensive measurement 
device is the GretagMacbeth (GMB) Huey which I have seen on ebay (new in the 
box) for as little as $50 plus shipping.  This includes the software.  Other 
options include the GMB EyeOne Display LT ($169 US retail) and EyeOne Display 
2 ($199 US retail).  These are the same hardware but the bundled software 
gives you fewer features if it detects that the device is an LT.   For most 
users the LT does everything they need and if you are using third party 
software that supports the EyeOne Display you will have exactly the same 
feature set as a Display 2.  Also the Display LT and 2 are often sold at 
significant discounts in the US.  I have seen LTs for as little as $99 plus 
shipping.  So shop around.

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