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Changing the Default "Save As" File Type in Preview

Medium Priority
Last Modified: 2012-05-11
How do I change the default Image File Type in Preview. I'm opening a JPG scan that has multiple images in it, selecting the image with marquee, clicking copy, then new and then saving the resulting file. It always defaults to PNG despite the original being JPG. Is there any way, presumably in Terminal, to change this default? There is nothing in the Preferences for Preview.
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Hi Willmcn

After some research including examination of the binary behind Preview itself - I do not believe there is any way to change this default.
A rather ugly workaround is to take screen-grabs using Shift-Apple-4. This supports changing the output format which can be achieved by running the following in Terminal.
defaults write com.apple.screencapture type image_format
killall SystemUIServer

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Be aware that this will not scale resolution correctly - rather you will get exactly what you see on your screen - be sure you have the original file displayed at 100% before taking a grab.

The alternative to all this, is to save the copied portion of the files then write a simple Automator script to change the file type from .png to .jpg. This would be far more effective for large batches.

Will LovingPresident, Dedication Technologies, Inc.


Thanks for your suggestion and taking the time to look at the binary. It's too bad Apple doesn't support changing this even in Terminal. You can change the default file format for screen grabs via Terminal or various freebie utilities so it seems odd that Preview doesn't off any kind of change. However, I like you suggestion of doing screen grabs. I'll have to see if these multi-image scans I'm receiving can be displayed at 100% and still be completely visible within the window but it might work.

I'm wondering if there is any image degradation by going to a screen shot rather than saving from the original?
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Will LovingPresident, Dedication Technologies, Inc.


Thanks Mak!
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