When I got my Macbook about 9 months ago one of the first things I did was change the default OSX screenshot format type from PNG to GIF. I edit a lot of images in Photoshop to post in technical articles and for the GIF’s I have been having to change the Photoshop Image Mode from Indexed Color to RGB to apply most filters during the process of editing the image. Photoshop loses a lot of functionality when an image’s Image Mode is set to Indexed so each time I modified an screenshot image and say wanted to apply a filter I would first have to modify the Photoshop Image Mode from Indexed Color to RGB. I recently got fed up with having to do that so I was looking for a solution when I realized if I just change the default screencapture format back to PNG the images open in Photoshop with the Image Mode set to RGB or Red/Green/Blue Color Model. Anyhow when doing so I started to wonder what image formats were available to set as the default screencapture format. Below I describe the details of what screencapture image formats are available in Mac OSX Lion and also what Image Mode that Adobe Photoshop opens each format from the Mac in.
How To Set Default screencapture Image Type:
defaults write com.apple.screencapture type <type here>
It makes sense before providing tons of details about each image format that you know how to set the format type using the Mac OSX Terminal window. So in the above command you would pick one of the image format types and enter that after type such as “type jpg”. Many people mention PICT, which is a image file type developed by Apple long ago, as an image type that can be used however it has been deprecated and is no longer available as an image format type for screencapture. I love the fact that they support so many screencapture image formats as I actually use different image formats for different tasks so being able to set screencapture image formats definitely makes my life easier.
Mac OSX Lion screencapture Image Format Types:
So again the available screencapture image format types are BMP or BitMaP, GIF or Graphics Interchange Format, JPEG or Joint Photographic Experts Group, JPEG 2000 or Joint Photographic Experts Group update in year 2000, PDF or Portable Document Format, PNG or Portable Network Graphics, PSD or PhotoShop Document, TGA or Truevision Graphics Adapter, and TIFF or TIFF/Tagged Image File Format. I tried a bunch of other formats including DCM or DICOM File Format, EPS or Encapsulated PostScript, IFF or Interchange File Format, PCX or Personal Computer eXchange, and RAW File Format but none of them worked when set as the image format type. Below is a table that includes details about each screencapture format type that can be set.
OSX screencapture Format Type Details:
The main point behind the table above is to be able to view your favorite image format to see first how it is saved on your Mac and second how it will interact with Photoshop. The only image format that really is a pain is GIF because Photoshop on the Mac opens that image format in Indexed Color Image Mode.
Color Profile: Monitor*
The other detail I noticed during the process of the above research was the Color Profile for each image type. As you can see above the Color Profile is noted as Monitor* for each image since this is something that depends on the monitor and possibly custom settings as well. I wrote another article specifically on changing an image or screenshot Color Profile type which can be located here. You can also make custom color profiles however if you can’t find one on the Internet that was created by someone who knows what they are doing I would advise against it since OSX does a pretty good job of picking the proper Color Profile.
The Alpha Channel provides the ability for full or partial background transparency. You can see the difference between an image format that has an Alpha Channel and one that does not in the two example image below. The first image format is JPG which does not have an Alpha Channel and thus cannot have a transparent background while the second image format is JPG 2000 which does have an Alpha Channel and this can have a transparent background.
JPG Image Format: No Alpha Channel, No Transparent Background:
JPG Image Format: Has Alpha Channel, Transparent Background:
Once all of the above information was analyzed I have switched back to using the default screencapture type which is PNG which I always open in Photoshop and then save as a GIF before uploading to the sites I write articles for. I absolutely prefer not having to modify the Image Mode in Photoshop each time I want to apply a filter or use the other Photoshop tools.