HowTo? Get PtGui/dcraw to accept "Lossy Compressed Dng's"?

[l_d_allan]

I attempted, without success, to get PtGui to accept "Lossy Compressed Dng's" (LCD) that were generated by LR4.3. My understanding is that the LCD format is equivalent to a high-quality .jpg that allows flexible adjustments to WB, exposure, gradients, etc.  It may retain .DNG flexibility, have quality between .jpg and .tif, and be much smaller in size than .dng's and especially .tif's.

 

Anyway, I hit problems, with the error message:

"dcraw error:

[[ file name goes here ]]

You must link dcraw with libjpeg!!

Cannot decode file

[[ file name goes here ]]

 

I'm able to make panos with the actual .dng files, although all ACR/LR pp is lost (as expected). To me, that suggests that my "vanilla installation" of PtGui is ok.

 

Admittedly, I wasn't really expecting PtGui to work with LCD's, but I had my fingers crossed.

 

Perhaps PtGui could work with the developer(s) of dcraw to get dcraw to be able to handle LCD's?

 

My desktop has 5 internal Sata's and an attached eSata enclosure with 8 drives, and it is rapidly filling up. And that is with keeping very, very few .tifs.

 

[PTGui Support]

Hi Lynn,

I'll add it to the wish list.

But keep in mind: as with any raw file PTGui will not be able to apply
any adjustments you make to the .dng in Adobe Raw. So what I would do
instead is convert the file to 16 bit tiff for stitching, and archiving
an uncompressed raw or dng file.

Kind regards,

New House Internet Services BV
Joost Nieuwenhuijse

-----------------------------------------------
PTGui - Photo Stitching Software

www.ptgui.com
For support see: http://www.ptgui.com/faq/
-----------------------------------------------

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[l_d_allan]

You may very well be correct, but my understanding is that an LCD is an odd hybrid between a DNG and JPEG.

 

If I read the Adobe white-paper correctly, the .dng is a "wrapper" around a very smart 8-bit .jpg. Each channel is optimized/flattened to fit best into that channel's available space.

 

Then within the LCD .dng, the equivalent of "sidecar .xmp" metadata is included to put it back together, along with WB, gradient, exposure, adjustments, spot-healing, snapshots, maybe history, HSL corrections, etc.  The LCD remains fully adjustable by ACR/LR, as only the "sidecar .xmp" info is changing.

 

I may have a flawed understanding of how it works, but my speculation is that dcraw could conceivably use an Adobe supplied API to apply the sidecar info to the embedded .jpg. From that point, it would be quite close to a garden variety .jpg.

 

For my workflow  ... lots and lots of panos ... this seems potentially advantageous.

[l_d_allan]

I've had some correspondence with Dave Coffin, developer of dcraw.

 

My understanding of his reply was that if PTGui built the dcraw library with a different combination of components, it might support Lossy DNG's. However, I'm unclear whether such Lossy DNG's would still ignore changes from ACR/LR like exposure, WB, gradients, etc.

 

I can share his comments with you, if appropriate.

dcoffin at cybercom dot net

[PTGui Support]

It's on the wish list Lynn.

Again, see my previous posts: Changes from ACR/LR like exposure, WB,
gradients, etc will be lost when importing the file in PTGui. If you
need any of these you will need to convert to 16 bit TIFF files, and
load those in PTGui.

Kind regards,

New House Internet Services BV
Joost Nieuwenhuijse

-----------------------------------------------
PTGui - Photo Stitching Software

www.ptgui.com
For support see: http://www.ptgui.com/faq/
-----------------------------------------------

> dcoffin at cybercom dot net <mailto:dco...@cybercom.net>