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How to access DNG Preview jpg?
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Author Topic: How to access DNG Preview jpg?  (Read 49428 times)
peterkrogh
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« Reply #15 on: March 25, 2006, 01:50:27 PM »

Joe,
Are you using an asset manager? (iView or Portfolio)
Peter
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Joe Reifer
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« Reply #16 on: March 27, 2006, 04:42:29 PM »

Hi Peter -

I am using iView Media Pro 2.64, and will be upgrading to 3.02 within the next week or two.
Is there a good way to pull the 640 pixel JPEGs out of iView? Maybe building a web gallery and just using the image files?

Thanks,

Joe
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Canon digital, Mac OS 10.45, iView 3.02
peterkrogh
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« Reply #17 on: March 27, 2006, 05:21:37 PM »

Joe,
Although that was planned, it does not seem to be implemented yet.  So the media needs to be present for there to be a web gallery or some kind of converted image.

If you are using DNG, then extraction of the DNG preview is very fast.
Peter
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Joe Reifer
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« Reply #18 on: March 28, 2006, 09:33:48 AM »

Thanks Peter. I am in the process of converting to a DNG workflow - if the jpeg preview extraction speed is much faster than RAW, then that's another nice benefit for me.  Grin
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Nick Rains
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« Reply #19 on: April 11, 2006, 03:19:22 AM »

Though I have yet to check this is so, I believe the newest iteration of IMatch can also access DNG embedded previews. Certainly Mario Westphal was intending including this but I think the DNG support in the program is outsourced.

Maybe others can confirm this new feature...

I used to use IMatch, when IView was less advanced. However I now use IView3 and now find it more intuitive, if less powerful.


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peterkrogh
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« Reply #20 on: April 11, 2006, 06:13:10 AM »

Nick,
If you think iView is not powerful, you probably have not explored it thoroughly.  What is missing that you want?
Peter
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Nick Rains
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« Reply #21 on: April 11, 2006, 03:54:35 PM »

Peter

I don't mean that IView is not powerful, it most certainly is, it's just that IMatch is more powerful.

There so many more functions, options, scripts, templates in IMatch but I think that they tend to confuse the user. And the interface is super-cluttered as well. I found IMatch very easy to use at a low level and it generates thumbs pretty fast, but to use it 'seriously' is less easy than IView3.

I am very familiar with IView and for my money it has the right mix of power and useability.

Nick
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jeremynicholl
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« Reply #22 on: April 28, 2006, 04:10:20 AM »

Currently, you access that preview only with iView MediaPro and idImager.  If you use the convert image function, iView will access the preview rather than the RAW data.

You need to make sure you have your preferences set correctly.  Use Manufacturer rendering and click "use embedded preview".

You will find that this greatly unifies the workflow.


This is a nice idea but:

So far as I can see iView can't read DNG files' colour profile, and since it can't it converts the profile to sRGB by default. At least that seems to be what's happening here. Bridge shows my raw files and the DNG derivitives as Adobe RGB98, but when the same files are placed in iView I'm sold they are sRGB. That means when iView extracts the JPG preview it is also in sRGB, which isn't what I want to send as proofs. Of course, I can then convert these back to the correct space in Photoshop, but that's not much of a workflow.

Am I doing something wrong, or does iView really handle DNG files in this manner?

Jeremy Nicholl
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gudbjargarson
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« Reply #23 on: April 28, 2006, 06:10:41 AM »

Imatch 3.5 can display the jpg preview of the DNG.  I use it to show full size slideshows of the coverted files from Adobe Raw without problems.

Regards,
Johann
http://joephotos.net
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peterkrogh
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« Reply #24 on: April 28, 2006, 08:41:06 AM »

Jeremy,
A RAW file does not have a "profile" as we commonly know it.  When you select a profile in camera, you are just telling the camera:
1. What profile to create the JPEG in
2. If you use manufacturer's software, that instruction wil carry over to how that software will process the image.

The embedded preview in a DNG is sRGB, even though it s not tagged as such.  iView correctly converts this to a tagged derivative file when it uses the preview.

You should do some comparisons as to how proofs render in different color spaces.  I think you will be surprised.
Peter
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jeremynicholl
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« Reply #25 on: April 28, 2006, 10:34:55 AM »

Jeremy,
A RAW file does not have a "profile" as we commonly know it.  When you select a profile in camera, you are just telling the camera:
1. What profile to create the JPEG in
2. If you use manufacturer's software, that instruction wil carry over to how that software will process the image.

The embedded preview in a DNG is sRGB, even though it s not tagged as such.  iView correctly converts this to a tagged derivative file when it uses the preview.

You should do some comparisons as to how proofs render in different color spaces.  I think you will be surprised.
Peter


I'm sorry, I was a bit imprecise in my original post. I realise a RAW file has no profile as such. I always shoot RAW+JPG, simply because I might need to send an image immediately. 99% of the time the JPGs are junked, but they are profiled by the camera as RGB98.

What surprised me was the following. When I viewed the RAW files in Bridge they were tagged as RGB98 as I expected. When I converted the RAWs to DNG and viewed them in Bridge they were still tagged RGB98. But when I put the DNG files in iView and extracted the JPGs I found these were tagged sRGB. When I looked in the iView "Manage Colour Profiles" action I was told "The selected media item can't be colour managed. Only RGB, CMYK and Grayscale Photoshop, TIFF or JPEG images are supported."

That made me think that iView can't colour manage DNG files [presumably because they are in effect RAW files], but applies an sRGB profile to the extracted JPGs. I assumed iView was simply making a bad call. But you seem to be saying something different: namely that Adobe have decided to make the DNG embedded preview sRGB, but without tagging it as such. If so it seems a very odd decision for two reasons. Firstly to make it sRGB rather than, for example, RGB98: after all the latter is "Adobe's" colour space.  And secondly, not to tag it at all: whatever happened to colour management?

I used the term "proofs" very loosely. What I was hoping to do was solve a problem which sometimes appears - like today - when an editor suddenly says she woud like to see "what we've got so far" halfway through a shoot. I'd hoped that I could simply batch process the DNG files in Bridge's auto exposure, extract the Pretty Good Print JPGs, and send those. But just as some clients think "we need it at 300dpi", plenty will say "we need it in RGB98". If they suddenly receive images in a different space they get confused.

The obvious workaround is to convert the extracted JPGs to RGB98, but even with a script that's an extra step in the workflow, and one which would not be necessary if the extracted JPGs were in a more logical colour space.

Jeremy Nicholl

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peterkrogh
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« Reply #26 on: April 28, 2006, 10:03:33 PM »

Jeremy,
Try actually doing this in iView, and comparing it to the Adobe1998 results in ACR.  Again, I think you will be surprised at how small the difference is (depending on the image).

It's not an odd decision, considering that sRGB is more likely to be reproduced accurately if you are sending it out, and don't know for sure that the person receiving the file has any idea how to practice color management.  This is a very common situation.

Many more will be confused by Adobe1998 color space than by sRGB.

And if an editor is savvy enough to specify a color space, a well-corrected sRGB file will generally be a welcome relief to the unmanaged, oversharpened, clipped, and out of gamut crap they would typically see coming in.

That said, I do think it would be nice if you could specify the color space of the embedded preview.
Peter

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jeremynicholl
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« Reply #27 on: May 02, 2006, 11:14:25 AM »

Jeremy,
Try actually doing this in iView, and comparing it to the Adobe1998 results in ACR.  Again, I think you will be surprised at how small the difference is (depending on the image).

It's not an odd decision, considering that sRGB is more likely to be reproduced accurately if you are sending it out, and don't know for sure that the person receiving the file has any idea how to practice color management.  This is a very common situation.

Many more will be confused by Adobe1998 color space than by sRGB.

And if an editor is savvy enough to specify a color space, a well-corrected sRGB file will generally be a welcome relief to the unmanaged, oversharpened, clipped, and out of gamut crap they would typically see coming in.

That said, I do think it would be nice if you could specify the color space of the embedded preview.
Peter




Mmm, yes you're right, there's not much difference. And I'd forgotten about the "ignoramus on the other end" factor. Like you say, it would be nice to be able to specify the colour space but in practical terms it's probably not that important; I think maybe the sRGB surprise just made me grumpy.

Thanks for your help. And DAM good book by the way!

Jeremy Nicholl
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David
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« Reply #28 on: April 15, 2007, 11:25:52 AM »

My only problem right now is that I have some ORF files in my iView 3.1 catalogue and they now have a small preview so if I check the use embedded preview box in iView Media Rendering preferences I get this small preview in the image window as well as the catalogue window.

Now I am going to get my ORFs out of the catalogue anyway - but it bugs me. Did I put these previews in or are they standard in an ORF raw file.

Thanks

David
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peterkrogh
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« Reply #29 on: April 22, 2007, 06:12:41 PM »

David,
Sorry, I can't answer that.  Any proprietary Raw is specific to the camera.  You'll have to check with Olympus.
Peter
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