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Scanned JPEGs are large and slow to load - can they be optimized losslessly?

Scanned JPEGs are large and slow to load - can they be optimized losslessly?

I have hundreds of JPEG photographs which were scanned about 5 years ago from negative using a Konica Minolta DiMAGE Scan Dual IV. The dimensions are ~4500x3000, and the filesize is around 12Mb, compared to shots from a DSLR with dimensions of 3000x2300 and filesize of 2-4Mb (actually, these are the output from a RAW convertor). The filesize is obviously quite a big difference, but the issue that's bothering me is that the (perceived) loading time is at least 10 times slower.

Asked by: Guest | Views: 61
Total answers/comments: 2
Guest [Entry]

"4500 x 3000 would be a 3000 dpi scan for 35 mm film, which is a pretty good scanning resolution which will retain all the film grain. I get similar file sizes when I do this and save at the maximum JPEG quality setting.

If you want to optimise them for speed of display, then reducing the image dimensions will make much more difference than compressing them more (which cannot be done losslessly with JPEG).

If I were you I'd keep these original scans filed away and run copies through a batch resizer to get them down to (say) 2250 x 1500 which will display quicker in slideshows etc."
Guest [Entry]

"What software are you using to view the images? If you just care about viewing them on a monitor, using a program that creates a cached preview of the jpg is a good way to go.

I can recommend Picasa (free) and Adobe Lightroom (not free) for this purpose, as I've used them both a lot."