Wednesday, July 17, 2013


Immensely popular with consumers, Mac machines are gradually - and quite predictably - winning the medical imaging market. More and more Mac machines are used for diagnostic and reviewing purposes, especially as home workstations. The open source DICOM viewer Osirix enjoys great success in the medical world, and so does its FDA-cleared and CE-certified version, offered by Pixmeo.

But the thing is the sophisticated color management system Macs are equipped with can be quite tricky for a medical display. It offers many advantages for correct color and luminance reproduction, but can also present a risk, if set up incorrectly.

How Does Mac's Color Management Work?

Mac OS uses ICC profiles to apply a correction LUT (generally referred to as Gamma) to the desktop, but also applies 3D LUT’s inside the imaging application. Color management can not be deactivated on Mac, and a correction will always be applied both to the desktop and inside the imaging application.

The ICC profile selected in the System Preferences > Displays > Color will apply this correction.

The images below show that depending on the ICC profile selected the output of the display will be different. This means that incorrect color management settings can get the display off calibration, which is a risk you can’t afford for a diagnostic display.

So Which Profile to Select?

Creating an ICC profile for your display is a must if you want to get correct color and luminance reproduction. If you work in medical environment, you should calibrate your display to DICOM GSDF Part 14 and create an ICC profile for that calibration. This profile will modify display output as required for diagnostic and reviewing purposes.

What About Pre-calibrated Displays?

Pre-calibrated or factory-calibrated displays are generally calibrated on Windows machines. There is no ICC profile for these calibrations that could be applied on Mac. Besides, the Gamma on your Mac can differ from that on the factory-calibration Windows machine, so pre-calibrated monitors can still perform poorly on a Mac. That is why it is recommended to re-calibrate the display when it is connected to a Mac machine and create an ICC profile for this calibration.

Can I Calibrate the Display on Windows, Using a System Like Parallels Desktop?

The problem is that Windows is not able to apply 3D LUT’s of the ICC profile like Mac does, so Windows calibration does not take them into account. Consequently, the display will be correctly calibrated on Windows, but it won’t be on Mac.

Apparently, the most effective way is to calibrate a display to DICOM on your Mac machine and apply the resulting ICC profile in Mac color management settings

What do you think about the problem of DICOM-calibrated displays and Mac’s color management? How do you handle medical display quality on a Mac?


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