The Mask of QuickTime

by David Battino

What do you do when your QuickTime movie has ugly artifacts around the borders? Use QuickTime Pro's unlikely Mask feature to slice ’em off. Here's how.

For the recent O'Reilly Digital Media feature on composing music for mobile games, author Peter Drescher sent several movies of expert gamer Lucas Finklestein playing on a T-Mobile Sidekick. Due to the camera position, though, the movies had enormous black borders. Not only did that look strange, the borders bloated the file size. (See Figure 1.)

Fig. 1: Original movie

Fig. 1: The original movie had big, ugly black borders, but QuickTime Pro's Crop command snips out time, not area. What to do?


2006-08-18 17:37:00
This was amazingly helpful. Thank you so much.
2006-10-18 13:03:47
Thanks - was a good hint for me...
2007-01-19 03:11:53
I don't often leave comments but this little tip has saved me loads of time and money. I scoured the net and I think this is the only place that actually explains the technique properly.

Thanks a million...

2007-02-15 21:36:48
Quite nice indeed... Been holding off on upgrading to Quicktime Pro for awhile but this was enough to make me pull the trigger. Thanks!
2007-04-05 08:17:04
Thanks for the tip -- it's simple once you know how it works. Thanks again!
Paul T
2007-04-11 15:37:17
!!!!!! Cripes! I made some projects in iMovie DV instead of DV Widescreen, and I've been looking for hours to figure out how to crop out the black bars. Wow, this was simple, and perfect. I'm going to go buy an O'Reilly book of some kind to pay you back for this. Great!
2007-04-14 17:05:16
Ok, thats a cool trick but now can I go the other way with it?
I am making a movie in iMovie and iDVD but I have run into the TV safe area problem. Could I just add a black border around the whole movie effectivly shrinking the movie to with-in the TV safe area?
THAT would solve my very stressfull situation as the DVD has to be ready in a just a few days!
David Battino
2007-04-14 18:28:47
Nathan: Try this, using a rectangle that's larger than your movie but with the same height-to-width ratio:
David Battino
2007-04-14 21:20:53
Nathan (2): You might also check out the plugins at; Minify (just $2.50!) looks like it will do exactly what you need.
2007-06-03 15:00:13
The solution above sounds incredible.

However I don't have Fireworks or know how to "set Fireworks' canvas color to white and draw a black box over the part I want to keep. (See Figure 2.) Then delete the photo layer and export the black-box-on-white-background as a GIF."


Any solutions using basic Mac software or something in Adobe Creative Suite? Also what exactly are you doing with a black box with a white background? The pic shows a big black background. Is it supposed to be a black or white background? I'm a little confused.

Any more explicit step by step for people not familiar with graphic editors? Would a Photoshop work? Is that a graphic editor as well or just a photo editor.

Sorry don't have the assumed knowledge to take advantage of this solution, I fear. Any additional thoughts? Sure I'm not the only one with this problem who read this and didn't know how to do it. And don't have Fireworks.

David Battino
2007-06-03 22:43:00
@andintroducing: Thanks for asking. I see how Fig. 2 could be confusing. What you want to produce here is a black box with a white border, as seen in the bottom left hand corner of Fig. 3. It will look a bit like a film slide. (You can also make a white box with a black border and then hit the Invert button in QuickTime Player, but I digress.)

When you insert this black-on-white graphic into QuickTime Player as a mask, QTP will hide the parts of the image that lie under the white areas.

Almost any graphics program that lets you draw boxes will work to produce the mask. You can simply substitute “Photoshop” for “Fireworks” in the Fig. 2 caption. I like Fireworks (which is now a component of the Adobe Creative Suite ;-) because it’s like a streamlined combination of Photoshop and Illustrator, offering both vector and bitmap tools.

Generically, you can make the mask by copying a frame of the movie (Command-C), pasting it into a new graphics document (Command-N, Command-V), and then drawing a black box over the part you want to keep and white rectangles over the parts you want to hide.

2007-08-10 09:35:25
Thanks alot!
I don't know why qt doesn't just have a cropping tool. Thanks for the help.
2007-09-26 08:27:27
Thanks - really helpful, followed the instructions using Photoshop to produce the GIF with no problems at all. Anyone who isn't used to using photoshop might want extra instruction:

When you've copied your video shot to your clipboard, open a new file in photoshop and set the background to white and the dimensions the same as the original video. Paste in your video shot to its own layer, add a layer on top of that and draw your black box over the area that you want to keep in your video. Make the video shot layer invisible or delete it, then choose 'save as' and save it as a GIF with all the default options. Allow it to compress all layers and discard hidden layers. Then follow the other instructions above for using this as the mask in quicktime pro.


2008-06-21 00:35:06
I tried this technique .... but I get white spots on the QuickTime movie after I complete the crop ? Any suggestions ?
2008-06-21 13:31:33

I get white spots on the QuickTime movie

Strange. Do you have the latest version of QuickTime? Can you upload a screenshot of the effect?