IMovie Problems (Image size etc.)

Question

Please see this link for a detailed description the problem.
http://www3.telus.net/~jessum/PAGES/imoviequestion01.html
Dual G4 Tower   Mac OS X (10.3.8)  

Answer 1

Your "question02" seems to be OK. I would have done the calculations via a different route, though. But the end result is similar:
Your calculations seem to use PAL so I use PAL in my example:
PAL DV sampling matrix is 720x576, but PAL actual active picture size is 702x576, and the pixel aspect ratio for both is 128:117 = ~1.094.
http://www.iki.fi/znark/video/conversion/
Now, when those 702 and 720 horizontal square pixel rows are scaled to rectangular pixel rows on a TV, they are multiplied by the pixel aspect ratio 128:117 which gives us 768 for the actual active picture width and and ~788 for the sampling matrix width (the height remains the same).
Notice that 768:576 = 4:3 -- THAT is the 4:3 ratio on a TV! On the other hand the 788x576 square pixel sampling matrix figure includes 10+10 pixels on the left+right that can consist of black pixels. The pixels are black if the source is analog. But if the source is DV, then there usually is real material on the sides, too.
If the imported square pixel image's ratio is 788x576 (or any other similar ratio), THEN iMovie won't add black borders to it because it fits exactly to the 720x576 rectangular pixel sampling matrix. Usually it is best to use some larger multiple of those figures like 1024x749, 2048x1497, 2101x1536 etc so iMovie can better downscale the imported image (sometimes iMovie does this suboptimally thus rendering the images TOO sharp which causes flickering on an interlaced TV but I won't now go into that).
With 16:9, the ratio is (16:9):(4:3) = 4:3 larger than with 4:3. Multiply 702 and 720 with 4:3 and with the pixel aspect ratio 128:117 so you get the corresponding square pixels 1024 and ~1050. Notice that 1024:576 = 16:9 -- THAT is the 16:9 ratio on a TV!
Also then the 1050x576 sampling matrix includes extra material on the left+right that should NOT be included in the 16:9 aspect ratio calculations (a common mistake!). If the imported images' ratio is 1050x576, THEN iMovie won't add black borders to them because it fits exactly to the 720x576 rectangular pixel sampling matrix.
With NTSC the calculations are the same although some figures look weird: NTSC DV sampling matrix is 720x480, but NTSC actual active picture size is 710.85x486 (weird but true!), and the pixel aspect ratio is 4320:4739 = ~0.912.
So the square pixel NTSC actual active picture size is 648x486. 648:486 = 4:3 -- as weird as it may sound THAT is the 4:3 ratio on a TV!
Square pixel NTSC sampling matrix is 656x480. If the imported image's ratio is 656x480, then iMovie won't add black borders to it. ...but usually it is better to use an image that haven't to be upsampled in any direction so a similar ratio like like 720x527, 1024x751, 2048x1502, 2095x1536 etc can be used instead (BTW, iMovie HD 5-6 save still images as 720x528, which is a nice "coincidence").
With 16:9 the square pixel NTSC the actual active picture size is 864x486. 864:486 = 16:9 -- as weird as it may sound THAT is the 16:9 ratio on a TV!
With 16:9 the square pixel NTSC the sampling matrix is ~875x480. If the imported images' ratio is 875x480, then iMovie won't add black borders to it.
Now, didn't all that make sense!