Can I extract frames from bin clips in source frame size instead of project frame size?

[Harald Albrecht]

The title says it all: (how) can I extract frames from bin clips in 
source frame size instead of project frame size?

The background of my question: my projects use the standard FullHD 
1920x1080 frame size. However, some of my source footage comes from a 
tablet and are shot -- on purpose! -- in portrait mode(*). This footage 
is in 1600x2560 resolution, which is the native screen resolution of the 
tablet the footage comes from.

(*) vertical video syndrome ... nah! :)

As I need to mix this screen footage with screen still extracted from 
this footage, I need to have the extracted frames to be of the same 
dimensions as the screen video footage. Otherwise, ugly blurring kicks 
in, and while the video source footage looks crisp after getting scaled 
down to FullHD, the extracted frames look clearly visibly blurred.

Is there a way within Kdenlive to extract frames from bin footage in 
original resolution instead of project resolution?

At the moment, I need to first extract the frames in "low" project 
resolution. When the timeline edit is fine, I start a dummy project with 
a custom profile 1600x2560 10:19, and then extract the same frames 
again, this time in full resolution. Refreshing the existing project, 
the quality then gets good. But this is a hassle...

Best regards,
Harald