I've not had success with the procedure @Abdulatif suggested (for that matter, I don't even have success anymore with the procedures I've suggested!! )
The only thing that occasionally works for me is to run either the IconFixer app that was posted in this thread a long time ago (I don't think the download link works anymore, and the app fails to run successfully 50% of the time) or the Icon Cache Cleaner app that you can find through googling this problem.
No suggestion works permanently in this or any other thread I have found in this forum or any other on the entire net.
This is obviously a very annoying apple bug, which only appears if a folder with a lot of customized icons is opened in any applcation on the OSX and scrolled quickly, or if any application is used which works with thumbnails. (at least this is the root of the bug/problem for me!)
My only suggestion (BECAUSE APPLE DOESN'T FIX THE BUG IN ANY UPDATE SINCE 10.6...and now they are working on 10.8) to MAKE A FACEBOOK PAGE and make it grow into thousands of members.
Who is going to start a GROUP on facebook, so that this BUG will become more PUBLIC?
I suggest to name the group: "We want Apple to remain the best operating system." or "Apple's Mac OSX need some bug fix"
Who's going to start the group and link it to this forum? Let's clap the *** of Apple's software developers...because I'm tired of reading this thread since weks and months waiting for a solution to be found, which can only be done from Apple itself!
Patrick HCI wrote: "My workaround: I prevent MacOS from ever opening a folder with many high-res icons"
I think Patrick is onto something, but with different theory: since deleting the icon cache solves the problem temporarily, and most of the icons in the icon cache belong to applications, maybe there is a physical limit on the size of that cache that causes OS X to downgrade the icon resolution when the cache limit is exceeded - which could happen after upgrading or installing apps.
So, to test this I deleted a number of apps in my Applications folder to cut back on the size of that folder (I had a lot of old apps hanging around that I had demo'd but decided not to buy). I haven't had the blurry icon problem with anything - especially .dmg downloads - since. Knock wood - it's been several weeks without seeing this problem reoccur. Of course, if I do a lot of upgrades or buy some new apps, then the problem might return.
Well, I thought only that was the solution; obviously not.
Here are the exact steps
- Download Find Any File app (http://apps.tempel.org/FindAnyFile/)
- Install and open the app.
- Search for " thumbnails.data "
- Delete that file.
- Open system preferences and go to Display
- Change the resolution to the lowest possible and back to normal
- Log out and back in
That should be the solution, at least to me it was.
BTW I'm running Lion.
Had this problem from time to time, at random, with Lion. After Mountain Lion it is a lot worse... many icons, non only personalized but also system icons, look blurry and pixelated...
I have done EVERYTHING I read on the many threads about this issue here at apple, as well as on other sites, but nothing helped... (removed thumbnails.data, delete caches, deleter .DS_store files, finder preferences, etc. etc. etc.). Not using keyboard maestro... :-/
This happens on both my macs, an iMac 2011 and a MacBookPro 2010...
How is it possible to have this BUG since the last 3 version of the OS, with Apple not solving the problem but rather getting worse?
Sigh... YATF (Yet Another Temporary Fix)... I'm running Keyboard Maestro again. First I deleted it and the problem went away. Then I move it to being the last thing loaded by the system, and the problem went away.
and, of course...
with or without KM...
...now the problem is back.
But in my case, it's ONLY with DMGs. The icons in a window opened on the DMG are all blurry. (Rez'd down.)
Unfortunately, when I move a program or file from the dmg to my drive, it moves the lo-rez icon along with it.
Boy! This is sure annoying...
OK folks... here something new to try.
I'm a programmer. After suffering this on and off for over a year; after trying everything here, and finally, after looking at this and testing ideas for three hours today, I came to the conclusion that it was not some application that was causing the issue (at least for me) but some preference file.
In my current situation, the blurry icons are always on mounted .dmg's, and are always applications. After knuckling down, and finally reaching the "it's a preference file" conclusion, I did this:
FIRST: quit all running apps.
Next, went to my user/library/preferences and dragged
out to the desktop.
Then, viewing as a list, I sorted the display by size, putting all the Zero Length files at the top of the list. Then >SKIPPING THE FOLDERS< I hightlighted all the size zero files (which were all lockfiles) and deleted them.
Then I immediately rebooted. The fuzzy .dmg icons are gone, replaced by the correct sizes and resolutions.
The lockfiles are just directory entries, not real "files" occupying space on the disk (hence the zero length). I had over 1500 of them. They are used only to indicate that another file is open and in use, and therefore should not be opened by some other program until the first closes and releases it. (That's why I said to quit everything first, and then reboot after deleting them.)
As to the three plist files... hey, I did that at the same time, and things are working for me, so I left it in the explanation.
>> I would -strongly- suggest that, like with any such sweeping change, you HAVE A CURRENT BACKUP FIRST!
My speculation is that some system preference got "locked" (according to the lockfile) and thus could not be updated, resulting in either the finder, or the DiskImageMounter being unable to determine the proper resolution (or, who knows, maybe it was one of the plists...)
As with all the hundreds of other posts here, this may or may not apply to your situation, and if not, you have my sympathy.
But perhaps this will work for someone else besides me.
oops... too late to edit...
further work today gave me this:
Things stayed fine for a while, but then I opened one of my test .dmg files, and bingo - the blurry icons reappeared. My conjecture was that something in some particular .dmg files was resetting a preference file.
So, thinking about it some more, I once again deleted com.apple.frameworks.diskimages.uiagent.plist and immediately rebooted.
RIGHT AFTER I rebooted, and the OS recreated com.apple.frameworks.diskimages.uiagent.plist, I went back into ~/library/preferences, and (using plain old GetInfo) locked that file.
No problems so far; time will tell.
(I'm leaning toward this as my own solution. YMMV.)