[Scribus] Some ideas, and some clarifications maybe.

Hal V. Engel hvengel
Thu Dec 6 20:39:04 CET 2007

On Wednesday 05 December 2007 19:32:49 Richard wrote:
> Here is when my bad english becomes an obstacle, i dont know what you
> mean about this part.
> > All video cards have that capability (a colour look up table or LUT),
> > but I've never seen one that exposes it directly to the user before. You
> > normally have to load data generated by a profiling tool instead.
> On nvidia i have a colour correction panel and a slider for every color
> channel, maybe it's not professional, or as much accurate as it should
> but you can change R, G, and B channels individually on gamma contrast
> and brightness levels, it can also load an ICM or ICC profile.
> I may not know as much as you on colour management, profiling, printing
> or maybe not understand english too good, but i do know i can make my
> screen become out of any color at all.... (or full) and believe me, it
> is awful...
> My monitor, a 21" Sony Trinitron has a channel by channel adjustment
> too, among other stuff. And, if you put a colours sample or scale on
> screen you can see only some of them changing, remember screen is red,
> green and blue, so you can see cyan changing while moving on red slider,
> but not blue and so on.
> Probably if you're using a ndivia card you don't have coolbits enabled,
> you may give it a try.
> I repeat, i may not know as much as you on this subject but i do know i
> can handle colours so much by hand. Off course, color profiles installed
> or hand-tweaking is not the same. But i can have an approach to MY home
> printing colours at least, and with some patience maybe also a print
> shop approach, not 100% but as much as an eye allows. Repeating again,
> it may became insane to adjust like this, but when everything else is
> missing.....
> Best greetings...

Of course, you can make all kinds of adjustments to the video card and the 
monitor.  But as Craig pointed out you are doing this using your eyes 
(actually your eyes and mind) and how you perceive (this is the mind part) 
colors is highly dependant on your surroundings.  In other words if the 
lighting changes in your viewing area and you readjust your monitor you will 
likely come out with a totally different result (So which result 
is "correct"? Are either of them "correct"?).  In other words the result is 
subjective rather than objective and you want to eliminate as much 
subjectivity in this process as possible.

The Sony monitors are actually very good and all of them I have looked at 
(this is only a few so there may be exceptions) have more adjustments 
available than most monitors.  For example these have the normal RGB gain 
controls to set your white point (IE. color balance of the brighter tones) 
like most monitors.   And, unlike most monitors, these also have RGB offset 
controls (probably labeled as RGB brightness controls) that will allow you to 
set your black point (IE. the color balance of the darker tones).   

With a measurement device like a Huey or an EyeOne Display 2/Lt and software 
like LProf or ArgyllCMS these adjustments (RGB gain and RGB offset) can be 
set to be with in +-50K of 6500K (or some other value like 5000K).  This can 
be repeated every time these tools are used to make these adjustments no 
matter what kind of light is present in the room (the Huey should be used in 
a darkened room because it does have issues with light leakage).   You will 
end up with a result that is objective and not subjective.   In addition, 
tools like this make it possible to remove non-linearity's from the the 
displays response curves which is something you can NOT do using the video 
card and monitor controls.  The correction of non-linearity's is what Craig 
was writing about when he wrote "All video cards have that capability (a 
colour look up table or LUT), but I've never seen one that exposes it 
directly to the user before. You normally have to load data generated by a 
profiling tool instead."  He was correct about this.
 A few years ago when this measurement hardware started at about $300 US it 
was easy to understand why people were reluctant to purchase this hardware 
since it was by almost any standard expensive.  But nowdays using open source 
software and purchasing the hardware discounted on the net you can do this 
for about $60 US.  If you are doing color critical work and are spending any 
amount of money either printing on your own printers (after all ink, paper 
and wear and tear on the printer are not cheap) or having things printed by a 
print shop spending $60 to have your monitor correctly calibrated and 
characterized is actually a cheap investment since you will likely save that 
much in short order because of reduced printing costs (IE. fewer proofs 
needed or fewer wasted prints if you do this at home).

I should add that I am not saying that it is not possible to make things 
better if you carefully do a subjective visual adjustment of you monitor 
controls and the video card controls as compared to making no adjustments at 
all.   Rather my point is that measurement hardware and the related software 
will ALWAYS get you significantly better results and it will do this in a 
much more consistant, repeatable way and will remove all subjectivity from 
the process.  Frankly I was surprised by how much better my results were when 
I moved from using subjective visual methods to using measurement hardware 
and I think you will be as well.  But I suspect that you will remain 
unconvinced until you actually get a chance to see this for yourself.


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