ImageShrinker

ImageShrinker is a tiny and portable application designed to resize multiple image files in bulk. It offers support for JPEG, BMP and PNG file types, and it's capable of auto-uploading the photos to a custom FTP server afterward.

Portable tool with a simple UI

Since there is no installation involved, you can drop the .exe file in any part of the disk and double-click it to launch the program. It doesn't need any DLLs to run, remembers the configuration settings on exit, and doesn't modify the Windows registry. You can also store it on a USB flash drive to directly run it on any PC with minimum effort.
It's wrapped in a clear-cut interface made of a small window divided into three parts, where you can separately select the images, configure settings, and enter FTP uploading details.

Resize all pics from a directory

ImageShrinker auto-identifies all supported file types from specified directories, and it doesn't give you the possibility to filter them. Subdirectories are not taken into account for bulk operations. By default, the app renames the new files using lowercase letters and auto-deletes temporary files on task completion.
However, we've noticed a bug in the program. In fact, it deletes all new files after creating them, so it's mandatory to deselect the "delete temporary files" option to be able to use this tool without FTP uploads.

Set the photo size and FTP upload details

When it comes to the settings pane, you can specify the maximum width, height and JPEG quality for the new files, as well as remove the utility from the file explorer's right-click menu, where ImageShrinker gets integrated to be able to quickly resize photos from a selected folder. Apart from the fact that you can indicate the FTP server, user name and password, you can disable the FTP uploading option to keep the files offline.

Evaluation and conclusion

It resized images in reasonable time in our tests, during which it remained light on system resources consumption. No error dialogs popped up and it didn't hang or crash.
All in all, ImageShrinker offers a speedy solution for resizing JPEG, BMP and PNG images in batch mode. However, it's necessary to tinker with its options to figure out how it works.