Olympus OMD_EMI MKIII pixel sizes

[marcsitkin]

Looking for a hopefully quick answer. I've just rented an EM1-MKIII body for an upcoming trip, and in reviewing the test shots, I noticed that the pixel dimensions between ORF and JPEG files differs slightly.
I'm seeing 5184x3888 for JPEG, and 5240x3912 for ORF. Camera settings for capture LSF and RAW. Anyone know why the ORF files are slightly larger? Firmware is version 1.0. I'm using darktable to view files.

 

[RAH]

I don't know the reason, but I think that this is often (always?) the case with cameras - the RAW image file will be slightly larger in pixels than the jpg. No doubt part of the reason is that any jpg you get from the camera is heavily edited (in camera), and it is probably cropped slightly during this processing.

 

[L0n3Gr3yW0lf]

Looking for a hopefully quick answer. I've just rented an EM1-MKIII body for an upcoming trip, and in reviewing the test shots, I noticed that the pixel dimensions between ORF and JPEG files differs slightly.
I'm seeing 5184x3888 for JPEG, and 5240x3912 for ORF. Camera settings for capture LSF and RAW. Anyone know why the ORF files are slightly larger? Firmware is version 1.0. I'm using darktable to view files.

Just made an image in RAW + JPEG and I can confirm that they have slight different dimensions:

Subscribe to see EXIF info for this image (if available)

I think the difference between them is for lens corrections and possibly a bit more room for the IBIS to correct itself.

PS. Just remembered that the sensor pixel quantity is not exactly 20 MP:
Number of effective pixels: Approx. 20.4 million pixels
Total number of pixels: Approx. 21.8 million pixels

In JPEG it might try to maintain the marketing specification while the RAW file is a bit more loose on the pixel quantity.

 

[marcsitkin]

Just made an image in RAW + JPEG and I can confirm that they have slight different dimensions:
View attachment 899956
I think the difference between them is for lens corrections and possibly a bit more room for the IBIS to correct itself.

PS. Just remembered that the sensor pixel quantity is not exactly 20 MP:
Number of effective pixels: Approx. 20.4 million pixels
Total number of pixels: Approx. 21.8 million pixels

In JPEG it might try to maintain the marketing specification while the RAW file is a bit more loose on the pixel quantity.

Thanks for the confirmation. I so rarely import JPEGS that I was surprised.

 

[SrMiPhoto]

The raw file is indeed 5240x3912, but when you open it in Adobe's software it is automatically reduced to 5184x3888.
Which software are you using where you see the full size (5240x3912) for ORF? All post-processing software should automatically crop to reject low-quality parts.

 

[marcsitkin]

The raw file is indeed 5240x3912, but when you open it in Adobe's software it is automatically reduced to 5184x3888.
Which software are you using where you see the full size (5240x3912) for ORF? All post-processing software should automatically crop to reject low-quality parts.

I'm using darktable 3.6.0

 

[SrMiPhoto]

I'm using darktable 3.6.0

Here is a possible issue when not cropping:
https://github.com/darktable-org/darktable/issues/4966

 

[PakkyT]

I'm using darktable 3.6.0

You can probably test the lens correction theory by opening in darktable then exporting a JPG image. Then turn on the lens correction in darktable and output a second JPG. Do the two JOG numbers match the ORF and camera generated JPG numbers?

All post-processing software should automatically crop to reject low-quality parts.

Errrrr, what?

 

[SrMiPhoto]

You can probably test the lens correction theory by opening in darktable then exporting a JPG image. Then turn on the lens correction in darktable and output a second JPG. Do the two JOG numbers match the ORF and camera generated JPG numbers?



Errrrr, what?

For example https://github.com/darktable-org/darktable/issues/4966

 

[marcsitkin]

Why bother with any of it? The shots are fine, I'll get on with the work! Thanks for your thoughts.

 

[Growltiger]

The actual explanation is very simple. The aspect ratio of the sensor is 1.3855
The aspect ratio of a jpg is chosen by the user and varies. If the user sets the camera to an aspect ratio of 4:3 then it is cropped to an aspect ratio of 1.3333
If you look at the numbers above you will see this is the case.

(A note to anyone who thinks that the cameras are called 4/3 because they have a 4/3 aspect ratio. This is an incorrect assumption that is widely repeated. They were named that because the very first 4/3 camera sensors were based on video sensors with a standard diagonal of 1.33 inches.)