On 5/22/12 12:52 PM, Alex Zavatone wrote: > Just wanted to pass on this little pearl I just discovered in the > case that it might help someone else. > > I've got a bunch of images that I'm using as mapKit mapView overlays > for iOS devices and of course was interested in having them be as > small as possible and load as fast as possible. > > So, I took all the PNGs and converted them to JPEGs at varying > compression sizes and got them nice and small. > > Map drawing time went up terribly and the images and maps started > slowly chunking in on the devices. > > Don't use JPEGs. Use PNGs. it's a world of difference in map > drawing performance. > > Hope this tip/warning helps someone.
Note that as part of the build and bundling process, Xcode runs PNGs through pngcrush, which does a variety of optimizations that reduce file size and, I believe, do some hardware-specific decoding optimizations. The upshot of this is that a comparison of raw PNG and JPG files is totally meaningless; you would have to actually look at the post-pngcrush output, and even this wouldn't tell the whole story. If you are doing performance tuning, you should take a look at the pertinent documentation (e.g. https://developer.apple.com/library/ios/#documentation/iphone/conceptual/iphoneosprogrammingguide/PerformanceTuning/PerformanceTuning.html). There and in other docs Apple explicitly notes that PNG is "the preferred image format for iOS apps." (Something I hadn't really thought about is that this would suggest different performance for PNGs that are downloaded by an app versus those that are included at build-time. Does anyone know whether there is a noticeable difference?) -- Conrad Shultz Synthetiq Solutions www.synthetiqsolutions.com _______________________________________________ Cocoa-dev mailing list ([email protected]) 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 [email protected]
