On 24 Feb 2014, at 17:21, Mike Abdullah <mabdul...@karelia.com> wrote:
> On 24 Feb 2014, at 17:00, Kevin Meaney <k...@yvs.eu.com> wrote: >> I've written a command line tool that takes an image file (when testing I'm >> using JPEG files) and applies a custom CIFilter (a naive chroma key filter >> I've written) and saves a file to disk. Sampling the command line tool when >> processing files shows it is spending 90% of its time writing the png file >> of which most of this time is spent in a function called deflate in libz. >> The final file quality is good. I'm using CGImageDestination to export the >> file with default settings. > I’m a little unclear here. Are you saying the process appears to much slower > than you can reasonably expect? Or simply that you’d like to find a way to > make it go faster? (something which may well not be very possible) > I'd like one of two things, either getting the same quality exporting as TIFF as I do with PNG since exporting as tiff is more than 5 times faster, or that saving as PNG is faster. I suppose I don't understand when TIFF saving as uncompressed is meant to be lossless why is the image quality so much worse than saving as PNG. The ImageIO documentation relating to the dictionary properties when setting values to the CGImageDestination object, or when adding an image to the destination object are not really clear as to where to set which is appropriate. Secondly the description of the keys for the dictionary are not particularly helpful. Trying to work out what settings my work to achieve my goal is confusing and perhaps it is impossible. Both the speed difference between TIFF and PNG, and the quality difference surprised me. Kevin _______________________________________________ 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
