Does DNG correction crop the image slightly?

[BerndReini]

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Yesterday, I took a picture of a group of people with a man standing at the far edge of the frame looking out. As the preview was building, his nose was included completely in the frame. When the preview was built, his nose was slightly cropped. I tested this again by simply scrolling back and forth from a previous picture to this one and the same thing happened every time. The finished preview always showed a slightly cropped version of the initial image. I wondered whether this was just the case for the preview image, but when I opened the raw file at home, the man's nose was still slightly cropped. So my assumption is that this is part of the lens correction that is written into the DNG. I used a coded 50lux when I noticed this.

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[01af]

DNG Recover Edges

[BerndReini]

Awesome. Thank you so much. This might save a pretty good image.

[BerndReini]

I don't think the program was able to recover everything, but it is definitely nice to have it in an emergency. I wonder if it makes a difference when you have already imported the file into Lightroom. Would Lightroom change the raw file in any way? attach a script etc.? Anyway, there is just enough of the guy that it doesn't bother me that he is cropped now.

 

Before and After

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[ho_co]

Bernd--

DNG Recover Edges has almost no effect on Leica M files, picking up only a few pixels in each direction. (It tells you how many it has recovered.)

 

It's much more useful with Nikon and Canon files, and also with the Leica point-n-shoots, because they hide much more information than the M cameras.

 

Also, I don't believe it has been revised since Panasonic forced the redefinition of the DNG standard to allow the inclusion of lens correction data. That is, to recover edges of D-Lux 4 files, for example, you need to convert them to the earlier, linear DNG version as implemented by DNG Converter 5.2 or earlier.

[hoppyman]

That is very interesting Howard (regarding Panasonic and the DNG standard). Can you expand on where that info came from?

You are talking about DNG conversions in Post from the native Raw files from those Pannys?

 

As far as I know, no-one is actually taking advantage of the Op Code options in the current DNG standard as yet?

 

I'm very curious regarding what's happening in camera with the X1 though. I have a few files with their JPG versions too, I must go and look again.

I wonder how this applies to the Samsung and Pentax cameras when set to capture DNG natively.

Sorry for all of the ? there, I'm just always genuinely interested to learn more. I see the newest DNG standard as offering some more future possibilities for Leica Camera.

[BerndReini]

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Thanks Howard. The M9 seems to crop quite a bit more than what the program was able to recover. I would love to get the guy's nose back in the frame. Any other suggestions? I just framed too tight and everything was fast-moving here.

[ho_co]

Geoff--my brain isn't working well at the moment, but this may make sense.

 

When Panasonic, then Leica, came out with the files for the D-Lux 4 and its sibling, Adobe rewrote DNG Converter (ver 5.2) to record the RWL lens corrections into the DNG files. However, they had to de-mosaic the DNGs, so they are quite large.

 

Later, DNG Converter was modified (ver 5.4) to include the codes in the DNG, but write a still-mosaicked DNG.

 

All Adobe products that can read RWLs use the special software corrections.

 

Today I normally just run whatever the current version of ACR is unless I want to use DNG Recover Edges. In that case, I use DNG Converter 5.2. (You could do the same with the drop-down menu in ACR, but I've got ACR and DNG Converter 5.2 set to label the files differently, so I don't want to have to remember to change naming text each time.) Once you convert an RWL with DNG Converter 5.2, the edges can be extended by dropping the DNG onto DNG Recover Edges.

 

I also keep a copy of Capture One 4.5.2 around, because it was the last chance we had to produce a native, uncorrected DNG. Leica asked Phase One to discontinue the ability to write a DNG from the RWL in the next update after 4.5.2.

 

Summary: All Adobe products that can read RWL apply all the lens corrections. All Adobe products that can produce a DNG from the RWL write the corrections into the DNG.

 

The only way to get DNG Recover Edges to work with an Adobe-created DNG from RWL is to use DNG Converter 5.2.

 

Capture One 4.5.2 will create DNGs from RWLs without applying the corrections.

 

See examples at http://www.l-camera-forum.com/leica-forum/digital-forum/76810-d-lux-4-conversions.html.

 

Other threads by user macgarvin may be useful.

 

The info came from Adobe as they gradually updated their DNG abilities with the new cameras. I'm not up to researching the progress now, but it was documented on the forum.

 

Don't have any knowledge about X1.

 

Does that help? Or miss the base completely?

 

Note file sizes from a single RWL:

RWL = 10.3 MB

DNG = 7.1 MB from late ACR

DNG = 36.1 MB (de-mosaicked) from earlier DNG Converter 5.2

 

Only the third will work with DNG Recover Edges.

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[ho_co]

Bernd--

Yes, unfortunately, his nose is not recoverable so far as I'm aware.

 

I was hoping someone could explain why it seemed to get cropped as you watched the preview appear.

 

I was unclear in what I said earlier: With some cameras, DNG Recover Edges can sometimes be helpful because for some reason they don't use all the available pixels.

 

Leica, as you discovered, uses virtually the whole sensor to create its image, On the M8, DNG Recover Edges picks up only 4 pixels on each row and column. Note the "Dimensions" column. Both are the same file, but I ran DNG Recover Edges on the first one, labeled "ext".

 

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[hoppyman]

Aah that is fascinating Howard, thank you. I knew that the D-LUX 4 and its Panny sister had a special way of varying the proportions using different portions of the sensor and I knew that there was difficulty for some period gettting the Raw files to open with the Adobe Converters. I knew also that many cameras routinely correct distortion automatically in firmware as part of the image chain. Now I can see how DNG fits into that picture as well. Thanks again for taking the trouble to expand on that.

[jaapv]

I don't think the program was able to recover everything, but it is definitely nice to have it in an emergency. I wonder if it makes a difference when you have already imported the file into Lightroom. Would Lightroom change the raw file in any way? attach a script etc.? Anyway, there is just enough of the guy that it doesn't bother me that he is cropped now.

 

Before and After

Bernd, I wonder, in CS5 with the content aware repair tools, one could expand the canvas and create a bit of image to get him free of the edge.

[BerndReini]

Just to show you guys how severe the DNG crop with the M9 is, I copied the DNG back onto an SD card and took a picture of the finished preview and of the preview as it was building on my M9's LCD. How crazy is that? If the pixels are there, isn't there a way to recover them?

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[01af]

Try different raw converters ...

[hoppyman]

What is visible on the LCD is the low quality JPEG preview of course. Looking at the specs the DNG or JPEG actually normally available as stored are both the same pixel count though. That is 5212 pixels x 3472 pixels. The nominal active capture area of the sensor is 5270x3516. So you aren't losing anything specifically due to the DNG format there but have the chance to recover a very few extra pixels using the tool that Howard has explained?

If the figures are exact that is only 29 pixels of nose in this instance

[BerndReini]

I will try Capture One and see how it does. Geoff, the examples above are without and with the program and as you can see it wasn't able to recover that much. But on my screen shots, you can see that there is a big difference between the preview while it is building and once it is done. Both are JPEGs, just one in progress, the other one finished. Either way, as you can see, there is quite a difference between the before and after, so the chip must initially pick up the extra image area, which will then be discarded in processing. I was personally surprised to see that it is that much, even though I had never noticed it before.

[ho_co]

Bernd, thanks for posting the 'before' and 'after' shots. That's amazing.

 

I don't think a different RAW converter will make a difference in this case, but let us know.

 

I agree with Jaap that a slight extension in Photoshop is likely the only hope in this case, but adding the nose-guy's arm showing in your "while building" shot would require some finicky and talented hand-drawing in PS.

 

 

Only guessing here: Assuming that what we're seeing is an embedded JPG that includes the cropped info:

1) Is there a way to extract that JPG?

2) Then up-res it.

3) Then use the up-res as a background layer; place the DNG image atop it.

4) Crop any overage except at the left edge.

5) Use PS tools to mask the transition between the lower-res background and the DNG result.

 

 

Keep us posted. The fact that the nose is there at one point indicates to me that it must be recoverable.