Image viewer for multiple images

Comic viewers (such as Comical, Comix, QComicBook, or cbrpager) usually have a double-page mode.

In addition, Geeqie has two-image modes and a quadruple-image mode. However, the sub-windows seem to be independent of each other (when you change one, the others don't change).

Nomacs

https://github.com/nomacs/nomacs

I was looking for something to replace Google Photos locally to help organize my photos.

I need to quickly browse image thumbnails and do basic edit operations like renaming, rotation and cropping, and Nomacs fit perfectly!

When you open a directory with:

sudo apt install nomacs
nomacs .

you get thumbnails like this:

Double click on an image and it becomes big:

Then from there you can:

• Shift-T: back to thumbnails
• Left Right arrow keys: move to previous / next photo
• C: crop with mouse. Once done:
  • Enter: apply the crop
  • Esc: abort the crop
  • Ctrl + Shift + S: save cropped image as a new file
  • Ctrl + S: overwrite original file
  • Ctrl + Z: undo edit
• R: rotate
• F2: rename

Here's what crop mode looks like for example:

Some shortcomings:

• doesn't support videos: https://github.com/nomacs/nomacs/issues/191
• can't scan directories recursively: https://github.com/nomacs/nomacs/issues/297

Tested in Ubuntu 19.04, nomacs 3.12.