I recently digitized a large number of slides with a Nikon scanner and saved
the images as TIFF files (only options were TIFF or NEF. NEF created by
Nikon scanners is not supported by ACR so the logical choice was TIFF).
Since my workflow requires the addition of metadata to these images I
decided that DNG would be the ideal file format as the metadata can be
incorporated in the image without the need for a second XMP sidecar file
that can be easily lost or misplaced.
The tools I have found that can convert TIFF images to DNG are Adobe's
Lightroom and ACR hosted by Bridge CS3. Lightroom offers a simpler and more
straightforward conversion with not options offered. ACR hosted by Bridge
CS3 offers some options - compression and linear image. These options are
covered under the help files when the conversion to DNG is made from a RAW
file. However, the help files don't provide enough details about the
conversion from TIFF (and JPEG also) to DNG.
The questions I have are:
1. When converting TIFF to DNG is it possible to keep the image intact so
that it can be later extracted much in the same fashion that a RAW file can
be preserved should it become necessary to recover it later ? In this case,
what application could be used in the future to extract the original TIFF
image from the DNG file ?
2. The option to compress the original image as ACR hosted by Bridge CS3
makes the conversion can save some disk space but will it affect how other
applications open these DNG files ? Will other applications continue to open
these files and what impact will it have on performace (time necessary to
decompress and open image) ?
3. What does the linear option do the TIFF or JPEG file as the image is
being converted to DNG ?
4. I noticed that Apple's support for DNG is erratic and unreliable. I have
opened some DNG files with Preview but the ones I have created with both
Lightroom and ACR hosted by Bridge CS3 are not recognized by it. Why is
there a distinction in the way Apple's Preview treats these DNG files ? Is
there a difference between DNGs created from RAW files and DNG files created
from TIFF or JPEG images ?
Thank you in advance for your help,