Wrangling image file sizes, DPI and dimensions

Mr. Bsag is a printmaker, and often submits his work to open exhibitions. The requirements for this process are many and varied, but these days the initial round of selection usually involves submitting a digital image of your work. He now has a copy stand, and so he takes a photo of his prints. This is a tricky process in itself, because his engravings are often small in size, so difficult to capture in a photograph at an appropriate level of detail.

But then the fun starts. Every submission seems to require a different combination of DPI, maximum or minimum image dimensions, maximum file size and so on. Over the years we’ve tried a range of image editing applications to process the images for submission. It seems as if it would be an easy task, but (for example) the ones that allow you to set a specific DPI don’t give you a live estimate of file size, so you have to use trial and error to optimise the pixel dimensions and quality while remaining within the file size limits.

What I really want is an editor that would allow me to enter filter-like constraints (less than 3 MB, longest edge more than 1920 px, 96 DPI) and it would then pick the combination of variables that maximised image size and quality while satisfying all the other constraints. If anyone knows of anything like that, do let me know!

But She's A Girl @bsag