Link preview: Applying color filter based on current theme

["Tarjei Bærland via General discussions about Org-mode." <emacs-orgmode@gnu.org>]

Hi!

I use a lot of simple hand-drawn sketches in my notes. Ideally, I'd like 
a setup where I could take a quick photo of these, and the crop and 
adjust saturation and contrast to the point where they appear as black 
pen lines on a white or transparent background.

It would be perfect if I could preview these in a way where the 
background and line colors match my current theme's foreground and 
background colors. I can write a imagemagick command for getting the 
colors transformed, so I guess what I'm wondering is whether it would be 
simple to call this command before previewing the image?

Regards,
Tarjei

PS: Thank you very much for taking on the role as maintainer, Ihor. I 
watched your Emacsconf presentation with great interest :)