4.2 slow loading images?

[Adelea]

Hi,

 

After upgrading to 4.2, loading images seems much slower.

 

Prior to this, I could drag a dozen or so (4k x 6k) images (jpeg) downloaded from my camera into paint.net, and they would load quickly - now it can take up to a minute to open 12 images.

 

Is this normal, or is something messed up on my installation? Windows 10 Pro (1903)

[Adelea]

After finding an older version of paint.net on FileHippo, I did some testing. I would drag the 12 images from a folder onto paint.net,  and start the stopwatch when I clicked 'open'

 

I reinstalled 4.2, so it was a clean install. Over 5 tries, loading 12 images took 70s +/- 2s

 

I then uininstalled 4.2, and installed 4.1.4, loading the same 12 images took 6s

 

So I wasnt imagining it, 4.2 takes 10 times as long to load the images.

Edited July 30, 2019 by Adelea
Adding detail

[Rick Brewster]

Can you send me some of these images? I can do some performance profiling and get it figured out.

[Adelea]

Thanks Rick - I sent you a PM with links to sample images.

[Rick Brewster]

For anyone else who's reading this: 4.2.1 fixes this. 

 

It was related to images with an embedded orientation tag. Like when you take a photograph in portrait mode. The same pixels are saved to disk as if you had taken it in landscape, but an extra EXIF metadata tag says "rotate the image by 90/180/270 degrees". However, the way Paint.NET was getting pixel data from WIC was not optimal, and it resulted in decoding the image over and over to get different regions of the image. A weird O(n^2) performance problem ...