Lens Correction Image Crop is Wrong

[barti]

Hello Affinity Team,

I found some strange behaviour of the Affinity Lens Correction (so far tested for the Zeiss Batis 2.8/18).

I did some extensive testing and came to the following conclusion: 

The Apple Core Image RAW Engine the distortion correction mimics the in-camera correction of the Sony A7III nearly perfectly.

The Serif Engine does not...

A substantial amount of the image is lost after distortion correction. (Best seen on the USB Cable on the Left

However, if I change the scaling of the lens correction using (Serif Engine) to 98,5% and perform a crop after development to 6000x4000, the result gets really really close to the in-camera correction.

I presume that the scaling was selected, so that the image has content all the way to the edges without cropping to 6000x4000. (The RAW has 6024x4024).

However, at a 98,7% Scaling all 6024x4024 pixels have meaningful information, all the way to the edge corner pixels.

So I wonder - why is the Serif Engine Distortion Correction unnecessarily throwing away information? 

I speculate that the difference comes from Apple using a manufacturer profile (stored with the RAW file) and Serif is using a dedicated/different Lens profile.

I attached my test images (scaled to 2000 pixels, but the effect is still visible).

 

Any ideas / tipps / help?

For me this means, I need to switch on Apple Raw Enginge. What would be the disadvantage of doing that?

 

Thanks a lot,

Matthias

 

 

 

 

 

 

 

 

 

 

Edited October 18, 2020 by barti
duplicate images removed

[barti]

Hello Affinity Team,

do you have any response?  Thanks!

[Chris B]

Hey barti,

Sorry for the delay. Is it possible for you to attach the core image as we'd need to do some side-by-side checks. 

You can usually back off the lens distortion scaling to 98/99 without seeing any alpha and retain the meaningful info.