> Le 24 août 2016 à 18:50, David Duncan <david.dun...@apple.com> a écrit : > > >> On Aug 24, 2016, at 1:23 AM, Jeff Szuhay <j...@szuhay.org> wrote: >> >> I’m using a bunch of layers to draw images to, compose them, and then draw >> into a viewRect >> with >> >> CGContextDrawLayerInRect( viewContext, viewRect, myLayer); >> >> Of course, I’m trying to pick the most reasonable size for my layers. I >> currently use 1024x1024 >> but could easily make them 512x512 or 768x768. >> >> So my question is, “Is is more efficient to draw the layer into a smaller >> viewRect (down-sample) >> or into a larger ViewRect (up-sample)?” >> >> Or does it even matter? > > It depends on if quality or performance matters more. > > Downsampling is generally more expensive because you have to deal with more > data and so you become more easily bandwidth limited, but at the same time if > you must resample an image, down sampling generally produces better quality. > Upsampling is the opposite of all that. > > So if performance matters more than quality, then you probably want to > upsample. >
Moreover, the performance will greatly depends the sampling algorithm you choose. CGImage provide a couple of algorithms with different tradeoff (see CGContextSetInterpolationQuality() and NSImage and UIImage equivalents). _______________________________________________ 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
