Pixel aspect ratio for stills

ericlast wrote on 6/20/2005, 7:29 PM
I'm about to finish a project that I want to end with stills of my daughter's show. The digital stills were taken at high resolution on a 4MP digital camera. The image sizes are in the range of 1626x1616, 2020x1244, 1704x2272, etc.

I'm aware from reading that the images should be reduced to 720x576 for use in the NTSC world. I'm also able to do this as a batch script in PaintShop Pro8.

My questions are:
1. Do I resize to 720x576 for all the stills, no matter if they're horizontally or vertically oriented?

2. Do I use a different aspect ratio if I'm going to render the project for use on a 16:9 TV screen?

I'm sure I'm missing some point about how to do this correctly, so any help is appreciated!

Eric

Comments

jimmyz wrote on 6/20/2005, 11:24 PM
I didn't reduce or change my 4 megapixel pics at all on my last project and they look great especially the pans.
Steve Grisetti wrote on 6/21/2005, 11:07 AM
Okay, without getting into a lot of extra details, understand that, unlike conventional photos, video uses non-square pixels. The dimensions of the screen image in pixels, believe it or not, are the same regardless of whether it's for a conventional 4:3 or a wide-screen 16:9 video (720 x 480 pixels NTSC). The difference is that, on a 4:3 video, the pixels are about 90% as wide as they are tall and, on a 16:9 widescreen, they are about 120% as wide as they are tall. Confused? That's okay. The program does most of this invisibly and you need only provide your photo in the proper dimensions.

Here are the basics:
For standard NTSC video, your photos will fit perfectly if they are 640 x 480 pixels (That's 640 wide and 480 tall). For widescreen, use 855 x 480.

If the photos don't come out to those exact dimensions, just make sure the longer of the two dimensions fits. You'll end up with some black space outside the other two edges and, if that bothers you, the alternative is to size one of your dimensions to the larger of the two and the photo will fill the screen and run off the longer sides. Even more confused? Sorry.

It gets a bit more confusing when you try to do any panning/zooming into the photo. You want enough resolution so that you do so without "pixelating" the image. So a good rule of thumb is to add about 50% to each dimension and you should have plenty of resolution for all but the most extreme zooms.

But there's really nothing to be gained by dropping huge, high-res images directly from your digital camera into your video. In fact, you might even overload the program when it comes time to render. Just use the numbers above and you should be just fine.

And those are the basics. Hope that helps a little.
Chienworks wrote on 6/21/2005, 11:40 AM
If you want to be slightly more exact, use 654 or 655x480 for 4:3 and 853x480 for 16:9. If you'd rather match the horizontal resolution instead of the vertical then use 720x528 for 4:3 and 720x405 for 16:9.

640x480 will result in 7 pixel wide black lines on either side. 855x480 will result in 1 pixel wide black lines on the top and bottom.
ericlast wrote on 6/23/2005, 5:29 PM
Thanks to all for the suggestions...

Here's what I did: I opened the digital pictures in Paint Shop Pro 8, and ran a batch file to change the resolution to 855x480 ('cause my eventual output will be widescreen NTSC). Some of the pictures look OK when I enter them into my timeline in VMS, but some make my daughter, who's already pretty short, look like a pudgy lilliputin!. (The original dimensions of the worst offending picture is 1208x1808)

Will things look better after I render the project, burn the DVD, and show it on a widescreen TV, or am I doing something really wrong? Nobody in the family will be happy to see my little girl transformed this way!

Eric
Chienworks wrote on 6/23/2005, 6:05 PM
Are you stretching the pictures in one dimension to change the size? If so, don't. You should be cropping them instead.
ericlast wrote on 6/23/2005, 7:37 PM
I'm using the "Resize" command, and forcing the dimensions to what was suggested in the earlier posts; this is not a cropping command...

What's confusing me a little is the whole reason for doing this in the first place. I'm aware that if the pictures are used at their original resolution, black bars will apear around the stills in the outputted video project...I've done this before and it doesn't bother me too much. However, I've read in some places that if you don't resize the pictures, you'll get distorted images because of the differences in the way computer monitors and TV screens handle resolution. If this is the case, I'd really like to make things "not distorted" - especially if it turns my kids into otherworldly beings!

Thanks again,
Eric
allyn wrote on 6/23/2005, 8:34 PM
i don't see any reason to resize the images before importing into vms. it just seems like needless work. vms will do the right thing and the photos will look correct if you import the originals.
Spot|DSE wrote on 6/26/2005, 11:11 AM
Allyn and Kelly are right, there is no point in resizing before coming into VMS. Let the Pan/Crop do it's job, or let the image simply exist in its native aspect and float it that way.
IndyGuy wrote on 6/27/2005, 6:20 PM
Correct me if I'm wrong, but doesn't the rendering process have to resize the photos, which then adds even more time to the job. It would seem that if you resized the pictures in some other software, which is normally faster, you could save on some rendering time.
Chienworks wrote on 6/27/2005, 7:36 PM
This is true to some extent, but probably by a much tinier factor that you are assuming. Vegas resizes very quickly, probably faster than you can do it using some other software. The time savings comes into play when you have lots of very large photographs. Vegas decompresses them all when starting to render. If the decompressed versions won't all fit in memory all at once then Windows will start paging them out to the hard drive and this will slow rendering down considerably. However, until you reach this point, the size of the photographs probably affects rendering time very little.
Storyman wrote on 6/27/2005, 7:53 PM
You might want to create a graphic of a circle, then import it into Vegas Studio using the the different processes mentioned above.

Once imported be sure to place a title of which version of the graphic is showing on the timeline, then render and export and burn a DVD. The results will show you exactly what is happening to the images and which process gives you the results you want.