CRT Monitor Calibration and Gamma curves. (For those who still have CRT Monitors)

[robski]

This looks interesting on the topic of printing and viewing image on screen

http://www.zuberphotographics.com/co...g/printing.htm

Colour management is a very complex subject and it takes a while for all the pieces of the jigsaw puzzle to drop into place before you can make sense of the picture.

I found this guy very useful in explaining the subject when I first started to get my head around the subject a few years ago

http://boscarol.com/pages/cms_eng/

[barrypriddis]

Clive/Rob
Thank you so much for your replies. A complex subject, but am starting to understand a bit more. I am just off to the Tall Ships in Liverpool, so will check out the link from Rob on my return on Tuesday.
Thank you once again
Barry

[robski]

After a bit of experimentation I have managed to get my Spyder2Pro to run in all 3 of the available version modes to explore what options are available in each version. It may not be 100% correct so feel free to chip in with corrections if you spot any errors.

P.S I created this table in HTML does anybody know how to get the HTML to display as a table in these replies. All I get is the HTLM text with all my attempts So your just have to suffer another jpg to download.

[robski]

Spyder2Express is the entry level version. No frills or options, it just gets on with the job using a standard(typical) target with a 2.2 gamma and 6500K (D65 Daylight) colour temperature. At the start of the procedure the user sets the monitors brightness and contrast so that highlight and shadow gray scale wedge patches are viewed correctly. Then the colorimeter sensor is placed on the screen which proceeds to read the various calibration patches presented to it. The procedure is fairly time consuming which is not a huge problem if you only had a few monitors to keep calibrated. However, it could turn into a full time job if you had hundred to do. When the process is complete you can view a test image before and after calibration.

Most monitors are factory set to a colour temperature of 9300K ( blue/white) which looks good for text on paper effect. So the first thing you will notice is warmer whites. The calibration does provide a good tonal range and gray balance. If you are clueless about how to setup and check your monitor calibration the product provides good results with little effort or knowledge.

Of course all of the about relies on the CRT being in good condition and the brightness and contrast being setup correctly. It reminds me of the time when I was asked to give an opinion on a high-end Mac monitor in our showroom. One look at it and I said the CRT needs replacing. Our "Colour Expert" said no it is OK it just needs calibrating. I then said you can calibrate that until you blue in the face it will never be right, I've replaced over 600 CRT in my time so I think I know a duff CRT when I see one.

The calibration tool attempts to make the best of whatever condition the CRT is in. As an experiment I badly adjusted the brightness and contrast to give a very dim display to simulate an aged CRT. The program duly went through it's process and completed without error. The test image looked dreadful as the program tried to over compensate. I don't know if other calibration products are the same but I think the program should do some basic sanity check and tell you your are wasting your time.

This version gives you no control of the Colour temperature or of the black and white luminance (brightness) levels. If the before and after calibration looks identical then all you have done is confirm the calibration was pretty good in the first place.

[Gidders]

Originally Posted by robski

... you can calibrate that until you blue in the face ...

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[yelvertoft]

Yes, I had that thought too Clive.

Rob, your comments on the calibration software just trying to make the best of a bad job are very true. I run my laptop most of the time in a dual screen mode with its own integrated screen plus a stand alone flat panel. The panel technologies are different and the calibrator does a good job of getting the shades to match between the two screens, but it can't match the tones. On both screens, a particular item will be the same 'colour' but one will be brighter than hte other, if that makes sense. I had been expecting a perfect match between the two displays after calibration, but I was clearly expecting too much from a budget laptop screen.