How big should a picture be, in order to look good in iMovie?
Good question, and one that's a lot harder to answer for iMovie HD than it was for iMovie 4. iMovie HD changed some important stuff about image sizes, and added new project types that differ a lot from each other.
Generally, the bigger the source image, the better. (Bigger in pixels. iMovie doesn't care about resolution.) Bigger gives you more flexibility in zooming or cropping later in iMovie HD.
Here's the problem: When you import a 4:3 image with a 1.00 Ken Burns zoom, iMovie HD will pillarbox the image (add black bars along the right and left sides). If you don't want pillarboxing to occur -- you want to fill to the edges of the video clip -- you either have to increase the KB zoom (which crops the top and bottom of the image), or crop the image yourself before importing it to iMovie HD.
STRATEGY #1: USE KEN BURNS TO CROP THE IMAGE
The easiest way is to import images with the Ken Burns zoom settings shown here. That eliminates pillarboxing of 4:3 images.
For MPEG-4: 1.00
For DV: 1.06 (1.02 if willing to accept a 1-pixel bar)
For DV Widescreen: 1.40
For NTSC HDV 720p: 1.36
For NTSC HDV 1080i: 1.36
STRATEGY #2: CROP THE IMAGE BEFORE IMPORTING IT
If you don't want to fiddle with Ken Burns zooms to eliminate pillarboxing -- yet you don't want pillarboxing to occur -- you must crop the images yourself before importing them to iMovie HD. That's not as hard as you think using iPhoto or Photoshop. iPhoto lets you do a custom crop, and Photoshop lets you use the marquee tool to crop to an aspect ratio. (Note we don't want to resize the image, we want to crop it. Resizing changes the appearance of the image while cropping simply changes the dimensions.)
Normally, it's best to crop the image as large as possible using the aspect ratio required for the type of iMovie HD project you're working on. Different types of projects want different aspect ratios.
The tables below show the aspect ratio to use, as well as the MINIMUM size (in pixels) for imported images.
If you plan to crop the image with Ken Burns, or do a Ken Burns zoom animation, the minimum image should be larger. When doing a 2x Ken Burns zoom, the image should be 2x larger than the minimum. When doing a 3x Ken Burns zoom, 3x larger, etcetera.
RECOMMENDED MINIMUM IMAGE SIZE & ASPECT RATIO
These tables show important project dimensions when working with images in iMovie HD.
Tables are best viewed with a monospace font. These dimensions are intended to eliminate pillarboxing by iMovie HD when importing the photo.
NTSC PROJECTS
Project Type Movie Size Minimum Import Size Aspect Ratio for Crop
Standard DV 720 x 528 720 x 528 1.364:1
DV Widescreen 869 x 480 874 x 480 1.818:1
HDV 720p 1280 x 720 1280 x 720 16:9
HDV 1080i 1440 x 1080 1440 x 1080 Photoshop: 16:9
iPhoto: 16:9.02
PAL PROJECTS
Project Type Movie Size Minimum Import Size Aspect Ratio for Crop
Standard DV 784 x 576 788 x 576 1.364:1
DV Widescreen 1040 x 576 Photoshop: 1050 x 576 Photoshop: 1.823:1
iPhoto: 1048x576 iPhoto: 1.818:1
HDV 720p 1280 x 720 1280 x 720 16:9
HDV 1080i 1440 x 1080 1440 x 1080 Photoshop: 16:9
iPhoto: 16:9.02
OTHER GRAPHICS
When importing text graphics created in other applications, crop to the minimum import size. That prevents iMovie HD from resizing the image while importing it, distorting the text.
Karl