What is AA and AF and what do they do?

November 28th, 2007

Question:  When reading reviews of games and graphics cards I come across AA and AF and sometimes things like 4xAA.  What does this stuff mean?

Good question!

AA stands for Anti-aliasing (sometimes you might see FSAA which stands for Full Scene Anti-aliasing).  This is a technique that computers use to make curved or angular lines less jagged.  The science behind this is complex but the idea is simple - to make what you see on the screen seem more realistic.

When you read something like 4xAA, this refers to a particular level of anti-aliasing (for example, 2x, 4x, 6x ...).  The higher the number the more sampling pixels are used and the better the image, to a point at least.  For example 4xAA is usually enough when running a screen at 1280x1024, while you may only need 2xAA to get the same level of quality at 1600x1200, and your performance will better as well.  There is no hard and fast rule, experimentation is the name of the game.

AF stands for Anisotropic Filtering.  This is used to improve the quality of distant textures on screen (for example, the landscape of a game).  Again, 4xAF refers to a particular level of filtering (1x to 16x).  The higher the number, the better the image (but the more computer power you need).

Other terms you might see ar HDR which stands for High Definition Rendering which is used to add lighting effects, and bloom which is similar to HDR but not as complex.

Firefox out now

November 27th, 2007

Another day, another version of Firefox is released.  Version fixes three high-impact security issues found in earlier versions.

Expect the new update to be coming your your browser soon.

SnagIt and Camtasia Studio for free

November 26th, 2007

Here's an offer that any blogger won't be able to resist - get a free copy of SnagIt and/or Camtasia Studio from TechSmith for free!  And it's all totally legal.

What's the catch?  No catch.  There aren't the latest versions of SnagIt or Camtasia but both are otherwise fully-functional and not time-limited or crippled in any way.

You can also upgrade to the latest version of SnagIt or Camtasia Studio for half price.

I'm a long-time user of both SnagIt and Camtasia (in fact, SnagIt is one of my most-used applications and over a course of a year I take thousands of screenshots) and highly recommend both.

Apple Mail vulnerability walk-through

November 21st, 2007

Heise Security has released information about an Apple Mail vulnerability which is the resurrection of a bug that affected Mac OS X Tiger back in 2006.

Apple Mail transports information about which program should be used to open a file (content type: multipart/appledouble;) in an additional attachment that is invisible to Mac users. Attackers can then call a shell script "image.jpg" and nonetheless have commands in the script executed. Apple took care of this security problem with an update in March 2006. This email has a shell script attached to it that is disguised as a JPG. If your version of Apple Mail does not have the patch, it will show the icon for an image but nonetheless execute the commands contained in the attachment without further ado. This script only opens a terminal and displays the content of the current directory.

Heise have a web app that will send you a test email containing an attachment that will open a terminal window and display the contents of the current directory. Out of curiosity I decided to take a look at this. Here's the steps users would have to go through to be compromised:

  • Receive an affected email.
  • Open the attachment.
  • Confirm that you want it opened.

Apple Mail vulnerability walk-through

And that's it. The good thing here is that the Mac OS does warn the user that this is an application that will be opened in Terminal. If users have their eyes open they should spot this.

Here's the fake JPG file next to a real one:

Apple Mail vulnerability walk-through

Here's what Get Info brings up:

 Apple Mail vulnerability walk-through

However, bringing back a bug from the dead is embarrassing for Apple. Hopefully this will be picked up soon.

HELP! My CD/DVD-ROM drive has disappeared!

November 21st, 2007

Question: HELP!  My CD/DVD-ROM drive has disappeared!  I can see it in Device Manager but not in Windows Explorer.  I'm running Windows Vista.

There is a fix for this, but unfortunately you have to go digging into the system registry.

Here's how you fix things:

  1. Fire up Regedit (Click Start and type regedit into the search box and click on the listing that appears in the Start menu).  Note that you will get a UAC prompt.
  2. Navigate to the following key:
  3. Click on this key and in the right pane and right-click on UpperFilters and choose Delete.
  4. Repeat the process for the LowerFilters values.

Reboot.  Job done!