Still image resolution for 16:9

Slim5819 wrote on 1/16/2007, 12:40 PM
This is a great board. I couldn’t begin to tell you about the many answers I’ve found here to my questions, answers which I haven’t been able to find in the whole VMS manual of nearly 400 pages.

Since doing my last DVD using VMS and DVDA I’ve bought a Sharp 32 inch LCD wide screen TV. In their manual they specify their LCD Panel as having 3,147,264 dots which I take to mean the same as pixels. They enter the dimensions as 1366 x 768 x 3) If you divide the 1366 by 768 you get the ratio of 1.78 which is the same as when you divide 16:9 which is, of course the wide screen ratio.

I am presently making a travelogue of a trip my wife and I took about 4 years ago and I am going to use a combination of video clips from my camcorder and slides from my 35 mm. camera. I’ve got a Nikon Coolscan Scanner which does a terrific job of scanning slides in the TIF format. In the past I’ve had no trouble converting these to JPG’s and then putting the stills into the timeline as needed.

My question concerns resolution. I use Adobe Photoshop Elements and I can quite easily edit and enhance the scanned slide and save in a number of formats, except I have had trouble saving in the PNG format so I am planning to save in JPG.

The manual and a number of contributors here say one should save in a resolution of 655 x 480 for NTSC TV. Since I have a wide screen TV should I not save in a resolution of 1366 x 768 to match the television resolution? I did one other travelogue before I got the Wide screen and it plays fine and automatically becomes wide screen and looks good on my Sharp but wouldn’t the additional resolution to begin with enhance the quality of my stills.

I plan on sharing DVD copies with friends who may or may not have wide screens and don’t know whether there would be any compatibility issues. With my other travelogue I never heard of any problems.

Also could anyone suggest the proper DPI for saving the JPG still image in Photoshop Elements?

Jim

Comments

Chienworks wrote on 1/16/2007, 3:21 PM
Are you rendering HD files or are you still making regular 480 line SD DVDs? If the latter then the most resolution you'll have is 655x480 for 4:3 or 853x480 for 16:9. In fact, it's even worse than this because all your images will be resampled to 720x480 and then either squished or stretched out to fit the screen. You cannot get higher resolution than this.

If you're rendering HD files then the image size is 1024x720 for 720i and 1920x1080 for 1080i. However, there is very little software available that will let you author and burn HD DVDs, and it's quite likely that none of your friends or family have players for these formats.

DPI is irrelevant in video. Don't even consider it or think about it. It's a completely useless setting and has no meaning whatsoever. Concentrate on pixel resolution such as 655x480 or 1920x1080 as this is the only thing that matters. Ignore DPI completely.
Paul Mead wrote on 1/16/2007, 6:10 PM
And speaking of resampling stills into video, I have found that VMS often does a poor job of resampling higher resolution (more pixels) photos down to video. I have finally accepted that if I want decent looking photos I simply have to resize the photos down to a relatively small size (say 1024 x 768, or so) before bringing them into VMS. The results are much better for me when I do.
Slim5819 wrote on 1/16/2007, 6:36 PM
Chienworks,

Thanks for your quick reply.

I'm just doing regular DVD's as I don't have an HD player.
Thanks for reminding me of the obvious and telling me to use the 480 horizontal lines as a basis for resolution and not to waste time with DPI calculations.

However, I wasn't quite sure why you said that VMS would resample to 720 x 480 which seems to give a different screen ratio than either 4:3 or 16:9. Though, when I think about it, 720 x 480 is the ratio of a 35 mm. slide in terms of width to height. Again I'm probably not catching on to something obvious.

I think what I will do is experiment with a few different resolutions keeping in mind your advice to and make a very short sample DVD (DVD's were only 19 cents apiece in packs of 100 at a local Fry's Electronics this weekend) and see what VMS and DVDA come up with.

Jim
Slim5819 wrote on 1/16/2007, 6:39 PM
Paul, I appreciate the response and advice about not wasting project space on high resolutions. Also, from what I've read elsewhere in this forum too many high resolution pictures will also slow down the rendering process.

As I told Chienworks above I'm going to do a bit of experimentation before doing too much work.

Jim
Chienworks wrote on 1/16/2007, 8:34 PM
Jim, all standard NTSC DVDs are 720x480. The thing you're probably missing is that digital video normally doesn't use square pixels. When creating a 4:3 video the pixels are "squished" narrower by about 9%. The resulting image is about 4.09:3, not exactly 4:3 since television pictures are actually just a hair wider than 4:3. This is why the proper square pixel size is 655 intead of 640. When creating a widescreen video the same 720x480 format is used, except that the pixels get stretched out about 18.5% to create a 16:9 image.

So, whichever format you're creating, and no matter what size the original pictures are, they get resampled to fit the 720x480 format that is stored on the DVD.