Can I refer to the image width and height in an argument?

Question

I want to convert multiple images into square format, filling any empty space with black. Assuming the images have a width of 1000 and a height of less than 1000 (or vice versa), I can do it like this (using PowerShell):

magick.exe convert -background black -gravity center `
-resize 1000x1000 -extent 1000x1000 `
-set filename:original '%t' '.\*.jpg' './%[filename:original]-resized.jpg'

However, I want this to work for arbitrarily sized images. I need to do something like this, which is not an actually supported syntax:

#...
-resize 'max(%w,%h)xmax(%w,%h)' -extent 'max(%w,%h)xmax(%w,%h)' `
# ...

Is there an Imagemagick syntax for what I'm trying to do?

Answer 1

In Imagemagick 7, use magick, not magick convert and move the input parameter to the first parameter position, i.e. magick '.\*.jpg'.

Then, to do what you want change

-resize 'max(%w,%h)xmax(%w,%h)' -extent 'max(%w,%h)xmax(%w,%h)'

to

-resize "%[fx:max(w,h)]x%[fx:max(w,h)]" -extent "%[fx:max(w,h)]x%[fx:max(w,h)]"