> Le 24 août 2016 à 19:33, Jean-Daniel Dupas <mail...@xenonium.com> a écrit : > >> >> 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).
Just for the record, here is a link with different technics available on OS X to do that: http://nshipster.com/image-resizing/ > _______________________________________________ > > 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/mailing%40xenonium.com > > This email sent to mail...@xenonium.com _______________________________________________ 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
