Comments on: Mac OS X 10.5 (Leopard): Why is the music file preview image so ugly?

By: justin

justin — Wed, 16 Apr 2008 20:15:22 +0000

as “ssp” said:
I’m much more concerned by the lack of proper playback/navigation controls which are a real decrease in usability.

–

I could not agree more. Why would they take out these controls? It there some way to get them back. I want to be able to fast forward/rewind the audio file. Pretty lame apple.

By: ssp

ssp — Tue, 01 Apr 2008 21:28:32 +0000

I see plenty of JPEG artifacts around the edges of the note in your graphics. Those don’t appear on my screen.

There definitely are different algorithms for scaling. I believe in that in principle, QuickDraw, Cocoa, QuickTime and Quartz Composer might use different algorithms for scaling. My guess would be that Cocoa does it in this case because we’re dealing with Quick Look. But that’s only a guess.

By: Pierre Igot

Pierre Igot — Tue, 01 Apr 2008 15:08:45 +0000

I used JPEG because the result did not produce any noticeable difference. Anyone can verify on their own Mac OS X 10.5 install that the graphic looks pretty much the same as above, even without compression.

I agree that it is a minor “inconvenience” compared to navigational issues and the like, but it still jars.

The PNG file you referred to looks much better, and paradoxically when viewed scaled in the “Preview” column in the Finder in column view it looks pretty good too (and still looks good if I vary the width of the “Preview” column, which causes further scaling).

So the problem might be not with the scaling algorithm used in for the “Preview” column, but with another algorithm somewhere.

By: ssp

ssp — Tue, 01 Apr 2008 14:56:54 +0000

P.S. It might be a good idea to use a lossless graphics format to illustrate issues like this one.

By: ssp

ssp — Tue, 01 Apr 2008 14:55:42 +0000

Just for the heck of it: My guess is that two things are the problem here: The original file (System/Library/PrivateFrameworks/QuickLookUI.framework/Versions/A/Resources/DisplayBundles/Music.qldisplay/Contents/Resources/music.png) already exhibits this effect to a certain extent. And the scaling algorithm Apple use makes it even worse when scaling down. I found that standard Quartz scaling often aggravates such artifacts – particularly on edges at an angle. Using a different algorithm like Lancozs might solve the problem.

I assume that using vector rather than pixel graphics for this could be another solution. No idea about how feasible that’d be in terms of the gradients used in this graphics and for the speed when scaling.

By: ssp

ssp — Tue, 01 Apr 2008 14:40:00 +0000

No, I have cover art in my music files, so I’m not seeing this.

I’m much more concerned by the lack of proper playback/navigation controls which are a real decrease in usability.