Home Newsletter Locations Diary

 Indexes

Portal
Magazine4U

Article

Screen Profiling

Screen profiling, or as some refer to it, monitor profiling or calibration, is an important step in the process of colour management workflow when producing photographs. It is the first step to accurate colours. When editing your photos you want to make sure the colours you see on the screen are as accurate to the colour you produced them at and an accurately profiled screen can give you something to compare the final printed image against. If the screen colours are wrong, so will everything else beyond this.

To find out more about the need to colour manage your system, see another article 'Colour Management', here we are going to concentrate on the process of how to go about managing your screens colour and both creating, setting up, and using the profiles.

To carry out the process of calibrating your screen and therefore creating a profile you need a monitor calibration device, and there are a number of different versions on the market from entry level to advanced. You can buy just screen calibration tools from around 60 up to combined all in one packages which include screen, printer, scanner, camera and more for around 950. We have a separate article looking at the dedicated screen calibrating equipment. It is necessary to have your own screen calibrator as the screen should be accurate at all times and the process will need to be done on a regular basis. As screens get older they deteriorate over time and so the profile needs to be adjusted to take account of this.

These profiling solutions provide colour accurate profiling for LCD, CRT and laptop screens and the whole process can take less than 10 minutes (in quick or easy mode), once you've got the profiler set up. Creating a screen profile is a 3 stage process.

The kit that you buy will contain instructions, and some like the Eye-One take you a step at a time while you're running the program. The information below provides you with a good idea of what you are likely to be doing, this is largely based on using the Eye-One kit, so there could be some difference with others.

Some systems offer an 'Easy Mode' which requires far less input and work on your part, than the outline below and is nearly as accurate.

1st Stage - setting up the screen calibration tool.

The screen calibration tool, called a spectrophotometer, needs to be connected to the USB port of you computer and also needs to be able to sit against the front of your monitor. It attaches to the monitor in one of two ways depending on which type of screen you have. If you have a CRT screen then it will be placed into a device which attaches to the screen with a suction cap. If your screen is an LCD or laptop then it will be placed into a device which hangs over the top of the screen with a weight on one end to give it stability. Whichever method is used the spectrophotometer should be placed at the centre of the screen.

The following should also be looked at/considered before you start measuring:

  • Make sure that there is no gloss or other reflection towards your monitor screen.
  • The surround lighting of your monitor workplace should be dimmed and neutral.
  • Use a diffuse room illumination that spreads the light evenly at the workplace.
  • There should be no light source in the viewing direction of the observer.
  • Use a hood at your monitor to avoid stray light.

2nd Stage - creating the profile.

This next stage involves using a piece of software to take you through a number of steps. There are two methods usually of doing this, a quick or easy mode version which in a couple of clicks it carries out the profile by analysing a sequence of coloured squares it flashes on the screen and then generates a profile file (.icc) and places it in the necessary directory/folder on your computer and usually sets the new profile as the default profile for the computer to use.

The other way, or advanced way is for the instructions to get you to carry out a number of tasks prior to it analysing. This will involve modifying the brightness, contrast and colour temperature of your screen. All these settings can be found within your screen menu functions - refer to your screens manual for details on where they are for your particular monitor.

The first thing the software will do is to calibrate your screen, this means it will be adjusted to match certain criteria. These are usually defined as the:

white point - defining the colour of the 'white' of your screen using Kelvin values. Typically a value of 6500 daylight white as this closely matches indirect daylight and is recommended for CRT or LCD screens for image reproduction.

gamma - (or tonal curve) This measures the difference in brightness or contrast between monitors. A Gamma value can be a value from 1.8 to 2.2. The 2.2 setting is recommended and close to the normal setting that is best for monitors.

luminance - (brightness level) this usually offers a number of preset values as well as giving you the ability to enter a custom value. Recommended values might be

  • For CRT monitors - 100 cd/m2.

  • For LCD monitors -  140 cd/m2.

  • For laptop screens - 90 cd/m2.

  • For older CRT monitors - 80 cd/m2 because they could rarely reach a higher luminance level.

  • Below 80 cd/m2 you should not set the monitors luminance.

Next the software will display a range of different colour squares on the screen and the spectrophotometer will measure the output. The software will then adjust the appearance of the monitor until the desire colour temperature and gamma is reached.

3rd Stage - using the profile

Finally the software will create the ICC profile for the monitor. At the end of the process it will ask you to name and save the profile. It should automatically come up with the correct directory/folder to store the profile, this should be:

PC Users

Win XP:    C:Windows/System32/Spool/Drivers/Color

Win 2000:  C:WinNT/System32/Spool/Drivers/Color

 

MAC Users

Mac OS X:  /Library/Colorsync/Profiles

Mac OS 9:  systemfolder/colorsync profiles

It should also automatically set this profile as the default monitor profile to use across your computer system, so you don't need to modify the display settings within your operating system, or within the software packages you use for editing.

One point to remember if you are a PC multi-screen user using a graphics board that allows two screens to be used at once you will only be able to calibrate your primary screen. In the same way if you have a laptop and connect it to an external monitor, the external monitor will not be able to be profiled. However every separate computer and laptop screen can be profiled and should be for a continual colour managed workflow system.


See also:

Colour Management

Profiling Equipment

Printer Profiling

 

This page:

Link directly to this page, with text or the button on right.

Text linking: Screen Profiling on Photographers Resource

Linking Instructions                            http://www.photographers-resource.co.uk/

Photographers Resource, all the information for the photographer