Best resolution to scan 35mm negatives to use in DVD video

[MatthewJ]

Hi All,

Still working on my project of editing together some family videos/photos. I am in the process of scanning some old(er) 35mm photo negatives that I will incorporate into the final video I'm making. I did some research to try to determine the highest resolution that I should bother scanning the negatives at, given that I'll be displaying them on a TV. This website has provided some helpful information for anyone else faced with this question:

http://www.scantips.com/basics1f.html

The conclusion seems to be that even factoring in HD TV and Blu-ray stuff, there seems to be little advantage to scanning negatives in at a higher resolution than 2000 dpi (even less for standard DVD and TVs). However, there seems to be a caveat that using a video editor and trying to do "Ken Burns" pan/zoon affects might benefit from the higher resolution scans:

"Many people use fancy video software like Adobe Premiere to create 'movie' DVDs, with sound and motion. The television screens are still the same size, but the trend today is to use large still images, a few megapixels, to allow zooming and panning in Ken Burns style. The software will resample to output the correct size smaller screen image for each frame. That subject is "video", not scanning, and I can't help with that."

Normally I wouldn't mind scanning everything at a high resolution (e.g. 4800 dpi) for archival purposes and for possible printing down the road, but at the moment I'm a bit under the gun to get this project finished in time to give it as a gift, and scanning negatives at 4800 dpi takes a LONG time. If I can get away with scanning at 2000 dpi it will save me a lot of time (but I don't want to do it if the end result will look bad in my DVD project). Unfortunately, I can't test things out at the moment (I'm doing my scanning today in one location, and trying to work on the video editing in another location over the weekend).

So my question is -- for anyone who has scanned 35mm negative slides for use in a DVD video that incorporates some pan/zoom affects, what resolution did you scan at to achieve good results, and do you have any other advice?

[Ron P.]

First, you need to understand that DPI (Dots per inch) has nothing at all to do with display on TV or a PC, they do not know what DPI is for. DPI is for print media only. So you need to determine how many PPI (Pixels per inch) would be sufficient for your images to be used in a video. For using Pan/zoom I have used double the size of my video production, ie; for 720 x 480, my images will be at least 1440 x 960. Lately I've just been leaving them in their stock sizes, which for my digital camera is around 2560 x 1920.

[MatthewJ]

First, you need to understand that DPI (Dots per inch) has nothing at all to do with display on TV or a PC, they do not know what DPI is for. DPI is for print media only. So you need to determine how many PPI (Pixels per inch) would be sufficient for your images to be used in a video.

I guess I'm a little fuzzy on the relationship between DPI and PPI, but in any case, the only setting I have available to me on my scanner is the DPI setting, so that's the main reason I am discussing this in terms of what DPI to scan at.

For using Pan/zoom I have used double the size of my video production, ie; for 720 x 480, my images will be at least 1440 x 960. Lately I've just been leaving them in their stock sizes, which for my digital camera is around 2560 x 1920.

For my digital photos, I have been leaving them at their stock size as well. For the scanned photos, I guess the question is what DPI setting I should use to achieve a comparable PPI. I'm hoping that 2400 DPI will roughly equate to the best quality I can expect on a 720 x 480 standard DVD display, but I'm not sure.

[Ron P.]

Sorry, I should have provided an example...
I just recently scanned several old photos to use with video. I have a Lexmark all in one. I set the DPI to 600, and the resultant image file translated into 3450px W X 2362px H. I saved my scanned images as TIF files, to preserve as much detail and quality as possible. The file sizes are somewhat large, but I have plenty of space to store them.

[MatthewJ]

Thanks Ron. I have also read that 600 dpi is the highest anyone should realistically scan a photo print at, so your practice confirms that it gave good results. For negatives, we can scan at higher dpi, however, if a photo print scanned at 600 dpi is OK to use in a DVD slideshow with pan/zoom effects, I suppose there's no reason why a 2000 dpi scan from a 35mm negative would not work with pan/zoom in a slideshow.

Did you use that 600 dpi scan of that photo in a DVD slideshow with pan/zoom? If so, how'd it turn out?

[Trevor Andrew]

Hi

As mentioned Dpi is not the size that video studio understands.
DPI is related to the print size.
You need to be relating to frames in, horizontal and vertical sizes in pixels.

High Definition video uses a max frame size of 1920 x 1080, (16 x 9 ratio)
An image using the aspect of 16:9 will fill the screen.
You don’t say what size HD size video you are working with, nor whether you are intending to make a Blu-ray disc. If you are intending to make a standard DVD then the frame size is significantly reduced.

I haven’t scanned 35mm for a while but is a little different to scanning images.
With images you can set full size of the final image. (Dpi and inches)

Scanning negatives or slides I think I was limited to Dpi.

The 35 mm negative 1.4in wide, when scanning at 2000 dpi the final file size will be about 2800px wide giving a very good quality and allow for the Ken Burns effect.

If the negatives are showing their age then scanning at top quality is not gonna improve things.
Reducing the Dpi will probably not be noticeable with regards to quality, but will significantly reduce the scan times.
Maybe worth doing a few test scans, 1000 dpi would give 1400px wide still producing good quality.

[MatthewJ]

Thanks Trevor. It sounds like scanning 35mm negatives at 2000 dpi is good enough for applying the pan/zoom effects, so that's the setting I've been using. Good to know.

[UncleBoo]

Hi Matthew,

The scantips site you mentioned (great site, btw) does go into dpi vs pixels & ppi, and gives some conversion examples. From reading scantips and other sites, here is a set of rules of thumb I've concluded to use:

For photos, 600 dpi is adequate (and 300 dpi is probably adequate for the less important/low quality stuff).
For photos with Ken Burns effect, 1200 dpi may be useful, but do some trial and error with the actual photos before committing to the extra time to do 1200 dpi scanning.
For slides/negatives, 2000-2400 dpi is adequate, but if making "archive" scans, 3000-4800 dpi my be useful. (If the slides/negatives are badly faded, it may be a waste of time doing anything higher than 1200dpi.)
For slides/negatives with Ken Burns effect, 3000-4800 dpi my be useful, but do some trial and error with your actual photos before committing to the extra time to do 3000-4800 dpi scanning

Regarding slides/negatives with Ken Burns effect, most people probably won't see the difference of the high-dpi scans, so it's questionable whether the benefit outweighs the cost of the substantially longer scanning time, especially if you're under time pressure. I suggest trying 2400 dpi, and if the result is good enough to your eye, go with it.

Final note: for slides/negatives, I highly recommend a scanner with a cartridge/fixture designed to hold the image(s) in optimum position. Most fixtures hold multiple images, which saves a lot of time.

HTH,
UncleBoo
Epson V500 scanner