At 03:26 -0700 16/08/08, [EMAIL PROTECTED] wrote: >From: Matt <[EMAIL PROTECTED]> >Date: Fri, 15 Aug 2008 13:54:32 -0700 >Message-ID: <[EMAIL PROTECTED]> >Subject: Problem with NSImage and .PNG file >Message: 4 > >I have an image that is 7200x32 pixels, which is used to store a series of >32x32 tiles. When drawing from this NSImage, the further towards the end of >the image (right edge) the subrect goes, the blurrier it gets drawn. >... >I found that the .PNG NSImage was returning a width of 7199.099 pixels, >instead of 7200. Manually setting the NSImage's width to 7200 before drawing >fixed this issue and resulted in the correct, non-blurry subrectangles being >drawn. > >Has anyone encountered this issue before? Is this a bug within NSImage's >handling of PNG's or could this be a problem with my image file itself, a >DPI issue perhaps?
It's a bug in the image itself, or rather, in the generating software. I have a bug filed (still open, rdar://5532687) which says, in part: >When saving .png files, Preview 4.0(467) generates incorrect values for the >file's DPI. >... >See http://www.libpng.org/pub/png/spec/1.1/PNG-Chunks.html#C.pHYs >The 'pHYs' chunk can specify either "unknown unit" (which makes the file >default to 72 dpi when opened) or "meter". Preview now seems to generate the >latter specification. As 72 dpi don't fit exactly into metric units, the >measurement is rounded up, producing the 72.009 value. >Solution: >When saving 72 dpi pictures, specify "unknown unit" in the 'pHYs' chunk. I haven't checked if that has been fixed in Leopard Preview, though; I suppose not, as the bug's still open. -- Rainer Brockerhoff <[EMAIL PROTECTED]> Belo Horizonte, Brazil "In the affairs of others even fools are wise In their own business even sages err." Weblog: http://www.brockerhoff.net/bb/viewtopic.php _______________________________________________ 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: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to [EMAIL PROTECTED]
