AspectRatio of Olympus E-PL6

[herb]

Hello Phil,

I had the opportunity to get some images of a Olympus E-PL6 camera and I have seen that - in case of RAW (= *.orf)  images - the MakerNote tag AspectRatio is shown as: Unknown (2 1).

A short investigation has shown that this camera always writes value "2 1" for AspectRatio of RAW images.

I downloaded also some *.orf files from internet for Olympus cameras: E-PL7, E-M5 and E-M1 and the AspectRatio values for these types are all displayed properly.

So please enhance the Olympus.pm file of Exiftool 9.82 as follows: '2 1' => '4:3', # seen for E-PL6 RAW images

Thanks in advance.
Best regards
Herb

[Phil Harvey]

Hi Herb,

Thanks.  I would like to understand this tag better.  What are the dimensions of an ORF from this camera?  Both the full size and the cropped size as reported by ExifTool?

- Phil

[herb]

Hello Phil,

For the *.orf image of E-PL6 camera I found the following image values:
- technical description: 4608 x 3456 pixel
- IrfanView reports:      4640 x 3472 pixel
- Exiftool reports:
  - AspectFrame: 0 192 4607 3263
  - CropHeight:   3456
  - CropWidth:    4608
  - CropLeft:        8 0
  - CropTop:        8 0
  - ImageSize(Composite): 4640 x 3472

I hope this answers your questions.
Best regards
Herb

[Phil Harvey]

Thanks Herb.  That may answer my question.  But I'm not sure I understand.  The AspectFrame has an aspect ratio of 3:2.  I wonder how that figure into things.  An AspectRatio value of 1 is 4:5, and 2 is 3:2.  So what exactly does "2 1" mean?  Could this be a 2:3 image cropped from 4:5, or the other way around?

- Phil

[Phil Harvey]

Hi Herb,

I've looked for a sample E-PL6 ORF image but can't find one.  If possible, could you send one to me (philharvey66 at gmail.com).  Thanks.

- Phil

[herb]

Hello Phil,

sorry for my late reply, but your questions made me thinking more about this problem.

So I read many posts in a German Olympus forum, where this problem was also discussed. They focussed on the behaviour of various RAW-developing applications. So e.g. Lightroom > 4.1 does not allow to develop more pixel than given within AspectFrame.
Their hint was to modify AspectFrame (of course) with Exiftool in order to get the full RAW format.

To get a better overview I made many pictures and found the following:
With E-PL6 (and I think also many other Olympus cameras) you can select the AspectRatio (e.g.: 4:3 or 3:2) and you can select the mode you make an image (RAW or JPEG). And for JPEG you can also the select the storage mode which influences the file size only. E.g.: LF = Large/Fine, LN = Large/Normal.

Both setting values are taken into account to get the AspectFrame. Please see the following table for details. 

Code Select Expand

Image Exiftool values
AspectFrame Ratio CropHeight/Width
4:3 RAW 0 0 4607 3455 4:3 3456 4608
JPG LF/LN 0 0 4607 3455 4:3 3456 4608
16:9 RAW 0 432 4607 3023 U(3 1) 3456 4608
JPG LF/LN 0 0 4607 2591 16:9 3456 4608
3:2 RAW 0 192 4607 3263 U(2 1) 3456 4608
JPG LF/LN 0 0 4607 3071 3:2 3456 4608
1:1 RAW 576 0 4031 3455 U(4 1) 3456 4608
JPG LF/LN 0 0 3455 3455 6:6 3456 4608
3:4 RAW 1008 0 3599 3455 U(9 1) 3456 4608
JPG LF/LN 0 0 2591 3455 3:4 3456 4608

I hope this answers the questions.

On the other hand I found 4 values for which Exiftool reports "Unknown (x y)" - e.g. U(2 1) in table above.
They are all for RAW with an aspect ratio selected different to 4:3. E-PL6 has 5 aspect ratio to be selected.

Please add these 4 value to Olympus.pm file.
By the way: why is aspect ratio 1:1 called 6:6 by Exiftool?

Thanks for your help in advance
Best regards
Herb

[Phil Harvey]

Hi Herb,

Great!  And thanks for the sample ORF.

This starts to make sense now, and fills in some missing blanks.  Thanks!

I don't know why "6:6".  The original source for the decoding of this is here.

- Phil