On Mon, Apr 12, 2010 at 8:59 AM, Chris Tracewell <ch...@thinkcl.com> wrote:
> > On Apr 6, 2010, at 8:16 PM, Ken Ferry wrote: > > This was once true, but is out of date. I'd like to see a test app. For >>> example, how do you know you aren't getting antialiasing? It may be that >>> you just don't like the output. :-) >>> >> >> Well - NSImageInterpolationHigh and NSImageInterpolationNone produce the >> same exact result - screen shot copy (control-command-shift-4) the imageView >> built once using NSImageInterpolationHigh and once using >> NSImageInterpolationNone then paste each into a Photoshop layer, align them >> perfectly and then turn the top layer off and on at 800% and there is not a >> single pixel that moves or changes color. >> >> The dropped image is roughly 1000 x 1000 (a screen shot PNG) and the >> imageView size is 200x200 >> >> To make sure the currentContext was correct - I log [[NSGraphicsContext >> currentContext] imageInterpolation] for each build and it shows the correct >> values 3 and 1 respectively. And then just to be super sure I I log >> [[NSGraphicsContext currentContext] isDrawingToScreen] inside drawRect of my >> NSImageView subclass and get YES. >> >> I did implement my own image sizing in drawRect and then used [self >> setImage] and it works great. Not sure what could be the issue. >> >> >> It would also be good to know what OS you are working on. >>> >>> -Ken >>> >> >> >> I'm using 10.5.8. - XCode 3.1.2 - iMac Core 2 Duo and the app is GC. >> >> What Jens is saying is probably true in 10.5, not in 10.6. Nevertheless, >> I would be interested to see a test app. >> >> -Ken >> Cocoa Frameworks >> > > > Thought I'd add some closure to this, even though it's a week later. I > believe Ken's original assessment to be accurate - that I am just not happy > with the resampling that NSImageView is doing. Using larger images with lots > of detail, like a screenshot, the problem is more pronounced, the same is > true for images with thin diagonal lines. More organic images that aren't > too big produce acceptable results. > > Of note, I tested an image in Photoshop that was struggling in the > ImageView and found that by sizing to the same size as the ImageView using, > "Nearest Neighbor" as the sampling method, resulted in identical > "distortion" or lack of smoothness per se. Nearest Neighbor has been a > resampling method in PS for as long as I can remember, but I isn't really an > anti-alias resampling method - it chooses the pixel values by proximity and > duplicates it - thus no new color values get produced. I have used it in the > past when needing to take, for example, a small bit icon or type element > that I want to enlarge without aliasing, to keep a pixel accurate > representation at a larger scale. Using this method to downsize will give > mediocre results at best. > > All of that to say, it seems that an NSImageView in <= 10.5 you'll be > getting that method for resampling - so yes it resamples, but the method is > not optimal. > You may be getting nearest neighbor resampling, but if the conclusion is that this is all NSImage is capable of doing then that part isn't accurate. Quart'z high quality interpolation is currently Lanczos, medium quality is Fant. I don't recall right now what low corresponds to right now, but I would think that no interpolation would be nearest neighbor. NSImage drawing is Quartz drawing. -Ken _______________________________________________ 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 arch...@mail-archive.com
