On Jun 8, 2013, at 2:05 PM, Jens Alfke wrote: > On Jun 8, 2013, at 8:01 AM, Ken Thomases <k...@codeweavers.com> wrote: > >> Alternatively, you could force the image to load and then use >> +[NSBitmapImageRep representationOfImageRepsInArray:usingType:properties:] >> to create an NSData from the image's representations and save that to file. > > Not a good idea. If you do this with images that were originally JPEG, you’ll > degrade the image quality if you save it out as JPEG again, since it’ll have > to run the pixels through the lossy encoder again. Or if you save it in a > different format the file size will go up a lot.
I haven't done the experiment, but I don't believe this is necessarily true. NSBitmapImageRep is documented (in the Snow Leopard release notes) as keeping the original image data and not re-encoding or exploding file sizes on being saved. "You should see less encoding and decoding of bitmap data as CGImages. If you initialize a NSImage from a JPEG file, then draw it in a PDF, you should get a PDF of the same file size as the original JPEG. In Leopard you'd see a PDF the size of the decompressed image." Search for "NSBitmapImageRep: CoreGraphics impedance matching and performance notes" on this page: https://developer.apple.com/library/mac/releasenotes/Cocoa/AppKitOlderNotes.html#X10_6Notes Regards, Ken _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
