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Archived - Mac OS X v10.6: About gamma 2.2

Gamma is a numerical value that describes the relationship between the varying levels of brightness or luminance that a monitor can display or a digital camera or camcorder can capture.

To better serve the needs of consumers and digital content producers, Mac OS X v10.6 Snow Leopard uses a gamma value of 2.2 by default.  In versions of Mac OS X prior to 10.6, the default system gamma value was 1.8.  Using the capabilities of ColorSync, the gamma value of 2.2 is automatically applied and seamlessly transitions your display, images and videos to the new gamma value. If you are a graphic or video professional, read below for more information.

This article has been archived and is no longer updated by Apple.

Gamma 2.2 for photos, images, and digital cameras

Mac OS X v10.6 uses ColorSync and color space information to correctly display your images on screen regardless of the display's gamma setting.  Most photos and images will look the same as they did in earlier Mac OS X versions if they contain ColorSync profiles or color space tags.

Popular image formats, such as TIFF, JPEG, and PNG often contain color space information either in a color profile or similar tags.

Digital cameras typically include information about the colors used in the JPEG images they capture.  Most consumer digital cameras will specify the sRGB color space.  More professional cameras will usually let you choose between either the sRGB or AdobeRGB color spaces.

To check your photo's color space or color profile, you can select the photo in the Finder and choose Get Info from the File menu. In the "More Info:" section you will see the color profile information.

Some images that do not contain color profiles might appear darker in Mac OS X v10.6 than they did in earlier versions of Mac OS X.  Adding the sRGB IEC61966-2.1 profile or Adobe RGB (1998) profile to these images lets them display correctly.

You can use Preview to add or replace a color profile to your images.  Follow these steps to add or replace a color profile to your image.  For batch processing of images, see "Using Automator..." in the below additional information section.

Note: When replacing the color profile, once saved there is no way to undo this process other than by restoring an earlier copy of the image. Make sure you have the proper color profile selected.  If you are not sure, duplicate the images or make a backup copy of the images. Tip: Time Machine is a great way to keep an automatic backup of your images and other files.

  1. Open your image in Preview.
  2. From the Tools menu choose Assign Profile...
  3. From the "ColorSync Profile:" pop-up menu select the appropriate color profile.
  4. From the File menu choose Save (or Save As to save a different copy).
     

Gamma 2.2 for displays and projectors

Displays

For most displays, Mac OS X v10.6 automatically generates a color profile based on the capabilities of your display which uses a gamma value of 2.2. If you are currently using a custom display profile, there is no need to change or update your custom profile; Mac OS X v10.6 will automatically use the gamma value contained in your custom display profile.

Mac OS X v10.6 includes a Display Calibrator Assistant if you wish to further fine tune your display settings and save a custom display profile:

  1. Choose System Preferences from the Apple menu.
  2. Choose Displays from the View menu.
  3. Click the Color tab, then click the "Calibrate..." button to open Display Calibrator Assistant.  
  4. Check the "Expert Mode" checkbox.
  5. Complete the Display Calibrator Assistant steps to create the display profile.

Projectors

Mac OS X v10.6 automatically generates a color profile for most projectors based on the capabilities of the device.  If it is unable to generate a profile, selecting sRGB in the Displays pane in System Preferences is recommended.

You can also use the Display Calibrator Assistant to adjust for different room lighting.

To assign the sRGB Display profile to your projector, follow these steps:

  1. Choose System Preferences from the Apple menu.
  2. Choose Displays from the View menu.
  3. Click the Color tab.
  4. Deselect "Show profiles for this display only" if it is enabled.
  5. From the Display profile list, choose sRGB IEC61966-2.1 to set your projector to the sRGB display profile.

To use the Display Calibrator Assistant to create a custom Display profile for your projector, follow these steps:

  1. Choose System Preferences from the Apple menu.
  2. Choose Displays from the View menu.
  3. Click the "Calibrate..." button to open Display Calibrator Assistant.  
  4. Check the "Expert Mode" checkbox.  
  5. Complete the Display Calibrator Assistant steps to create the display profile.
     
Gamma 2.2 for videos

Many modern media formats, such as those using the H.264 codec, contain color information that QuickTime Player uses to correctly play back your video, regardless of the display's gamma setting.

To check a QuickTime movie's attached color profile, you can select the video in the Finder and choose Get Info from the File menu. In the "More Info:" section you will see the color profile information.

Tip: You can use Automator to assign color profiles to your videos, as described below.

Additional Information

Using Automator to add Color profiles

To use Automator to add Color profiles to your images or videos:

  1. In the Finder, select all images and videos you want to assign Color profiles to.
  2. Control-click any one of the highlighted items and choose "Create Workflow" from the "Services" sub-menu.  This will open Automator with a workflow containing your highlighted items in a section that says "Get Specified Movies" (videos) or "Get Specified Finder Items" (Images).
  3. In Automator's Name search field type in "profile" to find the Automator actions of "Add Color Profile" (videos) and "Apply ColorSync Profile to Images" (images).


     
  4. To add the action item to your workflow, click and drag the appropriate Automator action item over to the workflow area below the "Get Specified…" section.
  5. Then in the action item, select the appropriate Color profile you would like to apply.
  6. Click Automator's "Run" button to apply the selected color profile to all of your highlighted items.

If you need to use a gamma value of 1.8

If you need to use a gamma value of 1.8, follow these steps:

  1. From the Apple menu, choose System Preferences.
  2. From the View menu, choose Displays.
  3. Click the Color tab.
  4. Click the "Calibrate..." button. The Display Calibrator Assistant opens.
  5. Click Continue.
  6. Click "Gamma 1.8".
  7. Click Continue.
  8. Click your desired white point.  "Native" is default.  
  9. Click Continue.
  10. Give your profile a name if you wish.
  11. Click Continue.
  12. Click Done.

To work with your Mac using gamma 1.8, select the gamma 1.8 display profile in Display preferences.

More information about color management

  • See this webpage for Apple's Color Management Overview.
  • See this webpage for Apple's Technical note about ColorSync.
  • See this webpage for Apple's Technical Q&A about Generic RGB profiles.
  • See this webpage for Apple's Technical note about Image Color Management.
  • See this webpage for Apple's ColorSync developer reference.
  • See this link for the International Color Consortium (ICC) website.
  • See this webpage for details about the sRGB color space.

 

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Last Modified: Mar 21, 2014
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  • Last Modified: Mar 21, 2014
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