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AuthorTopic: What is a matrix profile?  (Read 8263 times)

tmx3

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What is a matrix profile?
« on: February 18, 2010, 05:21:31 AM »

I've heard the term banded about - a specific kind of icc profile i'm guessing. I've seen the term used in conjunction with the abreviation TCR as well. Can anyone explain to me what they are and what they mean? Also if a profile is not a matrix profile what would it be? Where/when would you use/not use a matrix profile.

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Czornyj

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What is a matrix profile?
« Reply #1 on: February 18, 2010, 06:39:16 AM »

Quote from: tmx3
I've heard the term banded about - a specific kind of icc profile i'm guessing. I've seen the term used in conjunction with the abreviation TCR as well. Can anyone explain to me what they are and what they mean? Also if a profile is not a matrix profile what would it be? Where/when would you use/not use a matrix profile.

They're based on mathemathical model known as 3x3 matrix - an array of nine numbers that can convert any triplet of numbers to another triplet. In ICC profiles the 3x3 matrix consists of the XYZ values for each of the three colorants of the device. The profile also contains definitions of tone curves (TRC - Tone Response Curve) for each colorant. The device numbers are passed through the tone curves before conversion using the 3x3 matrix. Most editing spaces and display profiles are matrix based.
« Last Edit: February 18, 2010, 06:42:24 AM by Czornyj »
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tmx3

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What is a matrix profile?
« Reply #2 on: February 18, 2010, 08:43:35 AM »

Quote from: Czornyj
They're based on mathemathical model known as 3x3 matrix - an array of nine numbers that can convert any triplet of numbers to another triplet. In ICC profiles the 3x3 matrix consists of the XYZ values for each of the three colorants of the device. The profile also contains definitions of tone curves (TRC - Tone Response Curve) for each colorant. The device numbers are passed through the tone curves before conversion using the 3x3 matrix. Most editing spaces and display profiles are matrix based.

thanks for your response. so is a tonal response curve related to gamma? the same thing? Are all icc profiles are Matrix based?
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tmx3

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What is a matrix profile?
« Reply #3 on: February 18, 2010, 09:13:16 AM »

Actually I just thought of another not entirely unrelated question. If i use eye one match to create an icc profile for my external monitor on my macpro, can i then drag that same icc profile over the network onto my laptop and use it when i plug the monitor into my laptop as a second display?
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terrywyse

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What is a matrix profile?
« Reply #4 on: February 18, 2010, 10:10:05 AM »

Quote from: tmx3
Actually I just thought of another not entirely unrelated question. If i use eye one match to create an icc profile for my external monitor on my macpro, can i then drag that same icc profile over the network onto my laptop and use it when i plug the monitor into my laptop as a second display?

First, just to clarify one point, while all the typical RGB working space profiles (sRGB, ColorMatchRGB, AdobeRGB, ProPhotoRGB, et al) are all matrix-based and are all "monitor" type ICC profiles, it would be incorrect to assume all monitor profiles are matrix profiles....they could be either depending on the software used to create the monitor profile. The better monitor calibration/profiling packages will allow you to create either type of profile for your display but LUT-based profiles are typically of better quality and more accurate.

To your most recent question, I would assume that you CANNOT take a display profile from one system and port it over to another, even if both systems are sharing the same display. When you're calibrating/profiling a display, you're profiling a display SYSTEM of which the video card hardware is a part of. When you switch from your laptop to the desktop system, the display hardware is getting changed in the process. The one exception MIGHT be if you're using a display with internal LUTs (Eizo displays and their ilk) where the calibration software leaves the video card linear and only modifies the internal LUTs of the display hardware. Even then, I wouldn't take that chance as it only takes a couple of minutes to build a new monitor profile for the other system.

Profiling a display is not unlike profiling a printer where you're profiling a printing SYSTEM which includes the printer, ink, media and driver settings....a printer profile might not even be portable to another system by virtue of the other system possibly having an older/newer version of the print driver.

Regards,
Terry
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Terry Wyse
Color Management Specialist, Shutterfly Inc.
Dabbler in the photographic arts.

Pat Herold

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What is a matrix profile?
« Reply #5 on: February 18, 2010, 12:45:27 PM »

A matrix profile is sometimes best used for CRT monitors, and LUT-based profiles are preferable for most LCDs - because LCDs can have sudden spikes of color change.  For more information on this and other monitor questions, see the articles that came out in our newsletter awhile back:
http://www.colorwiki.com/wiki/Monitors_Part_Two
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-Patrick Herold
Tech Support www.chromix

tmx3

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What is a matrix profile?
« Reply #6 on: February 18, 2010, 02:25:17 PM »

Terry, yes hadn't considered the video card etc. good point. Patrick that colorwiki link is good, thanks to you both. I just calibrated the second monitor using eye one match and I have to say it looks pretty warm. At the end of the calibration it gives you a graphical representaion of the colorspace and a few other bits of information  including Color temparature> current which reads 5200. I have color temparature set on the monitor itself at 6500. Does anyone know what this value refers to? Does this explain the discrepency between the two? the monitor is a lacie 319
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Pat Herold

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What is a matrix profile?
« Reply #7 on: February 18, 2010, 04:05:26 PM »

That would explain it.  5200 Kelvin is quite a bit more warm than is 6500 K.  The i1Match program has help menus on the right side of the page which give a lot of information about the different color temperature options.  You can read up on them there.  From your screen shot it looks like you have asked the software to just calibrate this monitor at its native white point - without trying to bring it around to a specific white point color.  Instead, you would want to calibrate this display to the same white point your other display has.
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-Patrick Herold
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Jack Varney

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What is a matrix profile?
« Reply #8 on: February 18, 2010, 06:25:52 PM »

Regarding the reported color temperature, the target value was "native" i.e. your 6500K but you missed the target in making the adjustment and wound up at 5200K. That is why the monitor's images look "warm". Redo the profile and use the advanced track and you will see during the adjustment how close you are to the target. There should be no problem getting to 6500K if the monitor is functioning properly.
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Jack Varney
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