A forum member who goes by the name Myrddin was quick to point out that the Sepia adjustment has a bug. It does two things … one, it seems to produce a result equivalent to the Black & White adjustment. And two, if you undo it, it doesn’t produce the right result. It breaks the history system, essentially.
So, just to warn everyone. The 3.20 Alpha is way cool (not that I’m biased), but stay away from Sepia for now. I’ve found the bug, and the fix will be in the next update. Thanks for your patience.
paint.net blog 
How long do you think you’ll take for another alpha release, hopefully where the sepia problem is fixed. (take your time!)
Thanks for your cool sw
is there anyone developing a “grid” warp or similar plugin?
my case:
I’ve got some photographed text that I want to OCR.
the photograph isn’t too bad a quality, its a little warped, but the OCR is.
I want to try squashing or unwaving or unwarping the text lines so that theyre more easily recognised as a straight text line.
Some one has posted on the plugin forum but I didn’t see anything of specific use there.
I know theres a patent made on the grid method but I doubt if that’s gonna stop someone developing an alternative.I saw a java grid warp effect that was quite similar somewhere.
I was thinking along the lines of warp-splines with pull points and a smoothing algo or maybe each pullpoint with a vector.
I suppose you could place the spline point per point on the image.
A depth of influence parameter could choose the pixels nearest the spline as laid (that would look like a line thickness option in a certain sense), with above/below or centered as option parameters (a bit like the pen options on some printers).
Then you could click/drag a pull point and change its influence with respect to the original image.
just an idea.
Holy crap! Yesterday was pretty much the one time I’ve ever used Sepia. Lucky for me PDN didn’t check for updates!