DNG options and problems in ACR/Bridge CS3.

Dear members:

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,

Joseph Chamberlain

Joseph Chamberlain, D.D.S. wrote:

Dear members:

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).

You can do a batch conversion in Photoshop to PNG just make the action.
So you have scanned all the images in 12? 16? bit Tiff images?
What metadata are you going to save and whats going to alter when you save as a PNG file? besides the file size which will reduce by about 35%
You could always save as a LZW tiff file.

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,

Joseph Chamberlain