Reminder: if you find an image that is smaller than you would like it to be, you cannot scale up or increase the resolution of an image, in fact, it will worsen the quality.
Squoosh App
Squoosh is an app that works great for fast image scaling, resizing, compression, and conversion to other file formats. For example: if you find an image that is too large (greater than 5MB) you can use an app like this to compress the file size and maintain image quality for your exhibition.
Photoshop
Prefer using Photoshop for image scaling, resizing, compression, and conversion? We have a guest workstation with Adobe Creative Cloud at the VRC.