Using ExifTool Command Processor: -htmldump option

[lenmerkel]

WARNING: Entering geek territory 

ExifTool has a really neat option for examining the internal structure of an image file. With this option, you can use your web browser to navigate an interactive web page generated for your image file. It can help you visualize the structural data in the file, including various control blocks and embedded metadata. In fact, it will show you visually exactly where ExifTool gets its information from (and why it can't - if the information is missing). To fully understand everything you see, it helps to have available the Adobe TIFF specifications (freely downloadable - use your favorite search engine), as much image data derives from this.

I found this really useful when examining the differences between a DNG file saved by my Pentax camera, and a DNG file created by the Adobe Converter from a PEF file saved by the same camera.

Create an ExifTool Command Processor preset with the following arguments:

Code Select Expand

-htmldump0
-w!
{Application.TempFolder}\exiftool\%f_%e.html
{Files}

Run this against a selected file or files, then go to the output folder in Windows Explorer:

Code Select Expand

%temp%\exiftool

There you'll find the generated html which you can view in your default web browser by double-clicking the filename.

For help in navigating the generated web pages, see: http://www.sno.phy.queensu.ca/~phil/exiftool/htmldump.html

[jch2103]

Thanks - interesting.

[Erik]

Interesting, and may I ask, what was the key difference between what you found with the two DNG files?

I'm asking because I have had various Pentax cameras, and I struggled with DNG issues with my old K10d camera vs. converting PEFs to DNGs. 

I don't have any of those files anymore, but it's still a curiosity.

[lenmerkel]

Interesting, and may I ask, what was the key difference between what you found with the two DNG files?

Context: I use DxO Optics Pro 9 for raw conversion and much of my post-processing. There's a running topic on the DOP forums regarding the fact that DOP doesn't support opening DNGs unless they are produced directly in camera. I have a K10D and shoot DNG, which DOP opens just fine, and was curious to see why this would be. So, I shot some test PEFs and converted them to DNG with Adobe Raw Converter 8.5. I was surprised to find that the DNGs from ARC were processed perfectly by DOP, just as if they were created in camera! Intrigued, I tried various options in ACR to convert PEF to DNG (DNG standards 1.1, 1.3, 1.4, compressed and uncompressed, etc). Every DNG that came out of ARC was processed by DOP OK. So the DNGs must be pretty similar to the camera-produced DNG, right? Well, it depends on how you define similar - hence the exploration with ExifTool's -htmldump option.

I haven't complete the detailed comparison, which I hope to have time to do this coming weekend. What I can share so far is:

File Sizes (all ARC DNGs generated with full sized embedded preview, fast load option)

DNG from camera	16.5 MB
DNG from ARC, compressed	9.9 MB
DNG from ARC, uncompressed	21.3 MB

Just the file size differences tell us something.

The camera-produced DNGs have a big-endian byte order. The ARC-generated DNGs have a little-endian byte order. DOP clearly understands either (which any properly written software should).

The main IFD (IFD0) in the ARC DNG has several tags that don't exist in the camera DNG.

The ExifIFD in the ARC DNG has tags that appear to have been copied from MakerNotes in the original PEF (e.g. LensInfo and LensModel). The camera DNG doesn't have these specific ExifIFD tags.

The ARC DNG has several more SubIFDs than the camera DNG. These appear to be previews/thumbnails of various sizes that the camera DNG doesn't have (it only has a full size preview). Maybe generated because I chose the 'Fast Load' option for previews when running ARC?

Regardless, IMatch5 handles all of these DNGs - of course 

Edited: I forgot to mention that one of the tags added to IFD0 in the ARC DNGs is ApplicationNotes, which is basically an embedded XMP segment.

[jch2103]

Thanks for your investigations. I'm a happy DxO user also; but in my case the dng files I can't open with DxO are scanned images produced by ViewScan. Apparently this is a consequence of lack of documentation by Adobe about nuances of the dng format. (Not an unusual situation for Adobe to make it difficult for other companies.)

[Erik]

Thanks for your discussion.

I have a K10d, too, and actually had the experience of having ACR converted DNG files rejected by Bibble (in my case) whereas the out of camera DNG's were acceptable.

However, as you noted, the converted DNG's were always smaller file sizes than the out of camera ones.  Ultimately, I skipped using Bibble because I had found other software to work for me, anyway.

Interestingly, with the Pentax K5, the out of camera PEF and DNG's were the same size, so I stuck with the out of camera DNG's.  I mostly use Lightroom anyway, so I like having the out of camera DNG's for embedding the preview after development, which has saved me from having a ton of versions of my files.

Your experience with DxO is interesting.  I had never tried it because I assumed the results would be like I experienced with Bibble.  I still like using my K10d, so having access to the DNG's with DxO gives me incentive to try it.

Thanks.

[lenmerkel]

I have a K10d, too, and actually had the experience of having ACR converted DNG files rejected by Bibble (in my case) whereas the out of camera DNG's were acceptable.

Too funny - I'm also an ex-Bibble user.   My prior experience with Bibble also led me to assume the same issue would occur with DxO.