What is a reasonable file format for film scanning?

Question

I'm looking to use my CanoScan 8600F to digitally archive the photos I've shot on film.

The issue I've stumbled on is deciding on a file format. Ideally I'd like something that is lossless but with some reasonable compression.

So far I've tried (over the last few years):

TIFF - File sizes seem to be pretty big

JPEG2000 - Photoshop elements 4 supported it, but doesn't seem to have a lot of support else where

DNG - Not sure if this is an option for scanning

I'm also looking for some guidance on resolutions to scan at... this was asked in another question "What to consider when scanning 35mm film (and scanning in general)" but wasn't directly answered, other than to say that scanners were only optically capable of 1500dpi.

With some exceptions I don't expect to make prints other than maybe 4x6s.

I currently use Adobe Lightroom with my DSLR and my new laptop included Photoshop Elements 9, but I haven't used PE9 yet.

Answer

I would say TIFF is probably the best format. JPEG 2000, like JPEG, is still a lossy compressed format when you really try to save space (the lossless version can compress a bit, but not nearly as much as the lossy form, and some forms of the "lossless" wavelet compression still can't fully reproduce the exact original image.)

When scanning in an original or master image, it's really best to maintain as much image detail and color depth as you can, and TIFF is an ideal format for this. It is guaranteed to be lossless, supports a wide variety of color depths including high color depths, has very broad support across many applications on multiple platforms, and even supports layers and other advanced objects that can be created with applications like Photoshop. TIFF also supports the storage of metadata, like JPEG.

I am not sure if DNG is an option for directly scanning film, and even if it was, I am not sure what the benefit of using DNG over TIFF for a film scan is. DNG has more merit in the digital RAW workflow, as it supports storing native camera RAW data and metadata, which really wouldn't be of much use for a film scan (which is always going to result in RGB pixels anyway.)

Regarding resolution, I guess it might depend on the nature of the film. If you are scanning very grainy film, you might not need to scan at an extremely high resolution, however scanning at too low of a resolution will likely even interfere with grain detail (which does have an aesthetic appeal to many, and that aesthetic might be diminished at too low of a resolution... and I would consider 1500dpi to be fairly low these days.) I'm a digital photographer, however I have researched film quite a bit as I have a strong interest in large format. To my understanding, a low-speed, fine-grain film like Velvia 50 is easily capable of over 3000dpi, which is double the dpi mentioned in the article you have linked. I have done some 35mm negative scans of old film just for kicks, and scanning up to 4800dpi (the maximum optical native of my scanner) produces an astonishing amount of fine detail. I would say scan at the highest resolution you can so long as you don't see negative returns, and I wouldn't be surprised if 4800dpi or even as much as 6000dpi was necessary to extract all the detail from your film.

If the initial file size worries you, you can always downscale your master file a bit from a high resolution scan, which should help improve sharpness a bit while also saving a little disk space. High-ISO black and white film will generally require less DPI, however keep in mind that film grain is not ubiquitous in size and distribution, and the full quality and shape of a single grain may require many pixels to render fully.

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