Scanning Slides and Negatives: JPEG vs. TIFF - what do I really give up?

12/14/16 bit vs 8 bit per channel = big big deal.

RB

The difference from Jpeg and tiff is down to the picture itself. If the pictures are all pro like images then the better quality loss-less tiff will be great, but if you have thousands you will need one big hard drive. If the pictures are all family snaps etc whats the point it is not worth the drive space you may as well use the Jpeg to keep file size to a min. I have also done tests and you can not see much difference. Only pictures taken in Raw format from modern Digital SLR will look and adjust better in aperture - photoshop - elements etc.

not true - bit depth is a huge issue in making any substantial adjustments.

4000 pictures all tiff, thats some hard drive you need again are the pictures worth the effort ?

It is correct that visually a single JPEG-12 save of a well shot pic is hard to distinguish from a TIFF save, but it is still appropriate to save scans as TIFF files.

Why? Because TIFF saves much more image information (that is why the file sizes are larger) and scanning is a slow time consuming (ergo expensive) process. If the images justify scanning they justify saving as much image data as possible unless only low end web usage is ever planned for the slides.

Hard drives are cheap. Buy a 1-TB sized drive and use 10% of it to store your 1200 pix in TIFF format.

When my only reason for digitizing a film pic is for cataloging or web purposes I photo instead of scan because scanning is so time consuming. I use a simple homemade copy stand setup and shoot macro photos and it works very well, about one minute for a roll of medium format film. If, and only if, an image gets purposed for print does it get scanned.

-Allen Wicks

Since I am using Aperture, and a feature of Aperture is always maintaining the 'master' without change, do I not have some protection against image quality loss (i.e., beyond that which occurred during the initial scan)? Is there any adjustment that cannot be made within Aperture to a JPEG, that can be accomplished with a TIFF? Any other drawbacks that I should consider when using a JPEG as the 'master' for my images within Aperture (vs. TIFFs)?

Along the lines of Live Picture, which was the first colour correction software for ColorSync, and LinoColor which was the first colour capture software for ColorSync, Aperture constructs ICC colour matching sessions to show the colours different colour devices are capable of forming, and does not change the source pixels in the colour correction process.

Nonetheless, JPEG is a lossy model by definition. It works the way compression works in the CIEL a*b colour model or in Kodak's colour model for PhotoCD, that is, by destroying information in the chroma channels and preserving information in the lightness channel. Using JPEG as archival master is not a good idea imho, at least not if changes are to be made to the archival master.

For archival masters, select a colour correction ICC colour space (a 'working space' in Adobe terminology) that is large enough to hold any colours you are capable of capturing, and large enough to hold any colours the innumerable colour devices you will be matching to are capable of forming. You can use the Apple ColorSync Utility to check gamuts.

You cannot reproduce a colour that you do not have in your source colour space, even if the colour device you are matching to is capable of forming that colour. For instance, don't use sRGB that is too small to form the colour of pure cyan on bright art paper in ISO 12647 offset printing. And you may want to use TIFF that can be compressed losslessly. Always embed the ICC profile for the colour space in which you capture/corrected the image. Otherwise, there is no definition of the colours your colourants should form on colour devices that need to have the colourants changed in order to form the colours you intended.

/hh