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Author Topic: Problem with custom profiles for DNG-files  (Read 10727 times)
speedskater
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« on: June 04, 2016, 03:46:33 PM »

The raw format of my camera is DNG. Qimage can use my custom profile for images straight out of the camera.

I convert my DNGs with Adobe DNG Converter to increase the resolution of the embedded jpg-preview.

After the DNG to DNG conversion, Qimage stops to use custom profiles for those files. Instead of the custom profile Qimage uses the standard Adobe.icm. The image info (Ctrl+I) in Qimage still shows the correct camera model.

Is there a possible solution for that problem?
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Terry-M
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« Reply #1 on: June 04, 2016, 04:11:48 PM »

Hi,
What does QU report as the profile for the image modified by Adobe? You can see what it is in the exif bar below the thumbnails - hover over the thumb, it's the last item in the information. If between asterisks it is embedded.
I suspect Adobe is converting to Adobe RGB.
If you want a larger resolution embedded jpeg, extract in QU by placing image in queue, right click and choose Extract Embedded Images. You can then resize in QU using the conversion feature.
Does you camera produce a reduced size embedded jpeg, most modern cameras have an embedded jpeg the same resolution as the raw image?
Terry
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speedskater
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« Reply #2 on: June 04, 2016, 04:37:50 PM »

Hi Terri,

What does QU report as the profile for the image modified by Adobe? You can see what it is in the exif bar below the thumbnails - hover over the thumb, it's the last item in the information. If between asterisks it is embedded.
Qimage shows adobe.icm for the converted images.

Quote
I suspect Adobe is converting to Adobe RGB.
No, it definitely doesn't. The converted DNG-files don't have any embedded ICC-profile after conversion (original camera DNG-files also don't have embedded ICC-profiles).

Quote
If you want a larger resolution embedded jpeg, extract in QU by placing image in queue, right click and choose Extract Embedded Images. You can then resize in QU using the conversion feature.
But this procedure doesn't produce a larger embedded preview.


Quote
Does you camera produce a reduced size embedded jpeg.
Yes it does. Adobe DNG Converter is an easy way for a larger preview. It doesn't simply resize the embedded preview (as it makes no sense to resize a small pixelated image) - it creates a new preview from raw data. The larger embedded preview is needed bedause it is used in my DAM (IMatch) or when double clicking DNG-files in Windows Explorer.

As both the original and converterd DNG-files have no embedded ICC-profile and both show the correct camera model in Qimage's "Display Image Info" it should be possible to use the custom profile.
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Fred A
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« Reply #3 on: June 04, 2016, 05:46:57 PM »

Just  a comment.
Not that familiar with Adobe stuff, but the DNG converter is free, so I tried it.
I converted some raw DNG which I downloaded plus some of my own CR2 files.
They all lost their identity with regard to attracting the matching camera profile
MY Canon CR2 went to adobe .icc also.

I went further in the comments of users of DNG converter, and found many references to the EXIF data being changed/overwritten.
Listen to Terry.
You will get better images ith zero hassle.

Fred
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speedskater
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« Reply #4 on: June 04, 2016, 06:10:08 PM »

Hi Fred,

I went further in the comments of users of DNG converter, and found many references to the EXIF data being changed/overwritten.
Examining the images with Exiftool shows me that there are no problematic changes.

Quote
Listen to Terry.
You will get better images ith zero hassle.
Converting DNG to DNG doesn't alter the raw data itself, so the result is exactly the same (provided that the same profile is used in Qimage). I have done extensive tests in the past and compared the results with Beyond Compare - there is no visual difference.

As stated above converting makes sense for me because my camera embeds only small previews inside the DNG-file.

I don't have any older Qimage setup files, but I am quite sure, that my problems didn't exist in older versions.
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admin
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« Reply #5 on: June 04, 2016, 07:36:29 PM »

Recent versions of QU will drop the camera profile if it notices that the DNG has been resaved from an Adobe product.  The reason is that I got multiple complaints that DNG's exported from Lightroom had overblown/oversaturated colors.  I looked into the problem and confirmed that Lightroom changes the RGB data in the DNG, making the profile no longer applicable as they convert the RGB data from the raw (as saved) camera format to a smaller color space (it appears to be Adobe RGB).  I confirmed this with my own images by importing raws from multiple cameras into LR, making no changes, and exporting DNG files: the resulting DNG files had the RGB data modified and it was no longer raw RGB data as it came from the camera.  It appears that they convert the raw RGB data to Adobe RGB or they are using an intermediate color space that is then picked up/converted to Adobe RGB by DCRAW upon developing.  At that point, the best I can do is deactivate the custom camera profile in QU (if the camera has one) and let DCRAW do the conversion based on Adobe RGB: which DCRAW uses internally.

I have not confirmed the reason for LR altering the RGB data: I guess that may be valid for saving a DNG since RGB values are always relative to some color space.  Just don't expect DCRAW to be able to get the original RGB data back to the point that you can apply one of QU's custom ICC profiles anymore.  The custom camera profiles are only valid for raws directly from the camera card: that's just the way it is.  You should still get reasonably accurate color as the QU custom profiles usually make only subtle changes to color accuracy.  Admittedly, DCRAW can be a bit finicky about opening/reading raws that have been altered by other software.  It's always best to feed the original raws from the camera to software that uses DCRAW for raw developing to be safe.

Regards,
Mike
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speedskater
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« Reply #6 on: June 05, 2016, 07:31:41 AM »

Thanks Mike for your comprehensive explanation.

Qimage has always delivered the same result for my original and converted DNG-files (maybe because the originals already are DNG). The problem with wrong/oversaturated colors may be valid for some but not for all cameras.

In its current state Qimage is not usable for converting my DNG-files. Without a custom profile I get ugly reddish skin tones in my images (desaturating reds is just a workaround with unwanted side effects in other colors).

So why not make it optional. Either a general switch in raw format options or (IMHO a smarter solution) via profile naming (xxx stands for the camera model):
xxx.icm (profile is used only for originals)
xxx-adobe.icm (profile is used for all files from camera model xxx)

By the way I didn't backup my original DNG-files because there was no need for it. Qimage was my raw converter of choice for the past six years. When it stays as it is now there would be the need to switch to another raw converter (fear it is lightroom ...). For this case it would be nice if you would provide me with a download link of the last Qimage version with the old behavior, so that I would have time to switch.
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admin
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« Reply #7 on: June 05, 2016, 12:05:41 PM »

I've not found a single case where LR saves the original RGB data: it always converts it even when the camera itself saves as DNG.  If you could send me a link to one that you think wasn't altered (via color space), please put it somewhere like Google Drive and send me a link.  Maybe I can find a tag in the file that would allow me to switch.  That said, for now...

QU can assign any profile you like:

(1) Select the raw thumb(s) for your converted DNG's.
(2) Right click on one of the selected thumbs and select "Custom Filter".
(3) Click the button next to ICC override and select your camera's profile from \programdata\ddisoftware\qimage\profiles

You could even save that filter with a name like "Raw Camera Profile" and then all you'd have to do in the future is right click on thumbs and select "Predefined Filter" and select that filter.

Mike
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speedskater
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« Reply #8 on: June 05, 2016, 02:50:24 PM »

QU can assign any profile you like:
(1) Select the raw thumb(s) for your converted DNG's.
(2) Right click on one of the selected thumbs and select "Custom Filter".
(3) Click the button next to ICC override and select your camera's profile from \programdata\ddisoftware\qimage\profiles

Thanks for the workaround Mike. But doing it this way gives me the mentioned wrong and oversatuarated colors. For my camera it is not the same as the old behavior of Qimage (which gave me perfect results).

I have sent you a dropbox download link for an original and a converted DNG.
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speedskater
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« Reply #9 on: June 08, 2016, 12:18:22 PM »

Problem has been fixed with new version v2016.153.

Thanks a lot!

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