Thursday, March 04, 2010

Blueish "LED" Screens? (How To Make Them Colour "Correct"!)

More than one year ago, I reviewed my Samsung NC10 and half-year ago, I purchased my second netbook, a HP Mini 311.

Recently, I wished to replace my old and tired Panasonic Plasma TV Panel, which has served me more than 7 years now. I have inspected quite a lot of the current models, namely, CCFL Backlit LCD, LED Backlit LCD and Plasma Panels, still.

What I found with all those LED backlit screens, regardless of the size and the brand, are in common is that: They contain obvious blue colour cast (when mixed with exaggerated red colour added in some default colour modes, they look purpleish!). Such blueish screen displayed images are of course not accurate in colours, as there is always a blue colour overlaid on the whole display. Well, when the supposed to be White coloured backlight (actually its source and type) is Not White Enough, what could we expect?

So, what I am going to talk about and share in my this article quickly is my own remedy to those Windows based netbook display screens, those are almost all LED backlit ones. I made the a colour management (actually colour correction) profile using the Spyder2Pro "hardware" colour calibration kit set and now I open up my own profile file and make it available to download for all LED screen netbook users and readers of my Blog.

I have tried my netbooks and found that it works quite well. I believe that it is usable for other LED backlit netbooks or screens as well. So, how does it work? In short, it simply compensates the RGB errors as far as it can, by re-defining the RGB response curves for the display adaptor/driver to compensate for the blue tone and write it into a built-in Look Up Table (LUT) of the display adaptor. It works but don't expect total miracle as the LCD screen now act as a filter to compensate for the colour cast. Still, you cannot get totally correct colours for particular colours as the light source of your screen is actually Not White, but Blue! For example, I never found that Greens can be re-produced very properly, even after the "calibration"! Too bad.. :-(

Follow my instructions below and you can get my SpyderPro generated Profile works:-

1. Download this ICM colour management profile that I created using the Spyder2Pro;

2. Download xcalib (stands for X-Calibrate - but it has the MS Windows/X86 platform command line binary executable, but not just for Linux X-Windows!);

3. Download the Readme file for the xcalib to see the available commands and options of it and to learn how it works. To get help, simply type in "xcalib -h" and hit Enter/CR;

4. Now, put the xcalib and my ICM profile at a Folder somewhere in your machine, write a DOS batch file for running the xcalib with the required command line without typing it manually each time when you need it, e.g., during boot-up. You can download my batch file here, I put my xcalib executable and ICM file at the C:\xcalib Folder, for example;

5. If you want the batch file to be run automatically each time when Windows starts, creat a Shortcut to the batch file in 4 above, in the Windows' StartUp Folder and it will run automatically each time when Windows loads/boots;

6. Sometime you need to reset the LUT for your display adaptor of your netbook, e.g., when you connect an external display that is colour-correct. Under such circumstance, just run the xcalib with the reset command and you will get accurate colour again on the external monitor. For this purpose, you can download my this batch file here;

7. To view the RGB colour correction curve defined in the ICM for the colour correction LUT for loading into the display adaptor, you can download this software, called the LUT Manager, here. The LUT Manager can also load and reset the display adaptor's LUT for you, with a GUI, which may be easier to use for some people.

Well, enjoy! And if you are one of the people who want the ultimate colour accuracy for any input/output device, particularly as a DSLR shooter, I am quite sure that you should find my this article and the files that I share to be useful! If you succeed, please let us know and do state briefly the make/model of your netbook(s) or LED backlit screen(s). :-)

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