Extend canvas in one axis without adjusting the other - RealWorld forums

Hello,
Firstly, I have just downloaded Picture Resizer today and I'm so impressed with this piece of software.
I would like some help though if anybody is able to provide it....
I want to extend the canvas in the following way:
Only adjust the canvas up to the point where the smallest side is 500px and ignore other dimensions if they are already at or more than 500px and with the extended canvas in white.
For example:
If I had an image 370 x 1292 I want the new image to be 500 x 1292.
If I had an image 1100 x 163 I want the new image to be 1100 x 500.
If I had an image 420 x 480 I want the new image to be 500 x 500.
If I had an image 700 x 800 I want it to be ignored (as both sides >500)
The canvas must be white.
Furthermore I'd like it to just replace the exiting image thus maintaining the original image name.

I hope I have explained things clearly and thanks in advance!

I am afraid, Picture Resizer cannot do that. There are too many conditions and specialized requirements.

RealWorld Photos can use javascript to customize its batch operations and would be able to do what you want with a bit of effort, but it is not freeware.

Vlasta - Thanks a lot for your rapid reply. It's really appreciated.
I thought I might be asking a bit too much from one piece of software.
I still have many uses for Picture Resizer though and may be able to achieve my goal in several stages by dividing up the images first.
Thanks very much once again.