I’ve got a 7168x11008 PNG that’s 109MB—way bigger than it needs to be, and it doesn’t even have to be a PNG. I’ve got another one that’s 16000x8000 with big areas of solid and flat colors.
I know a few programs that are good for bulk resizing or converting images, but I’m looking for something that can analyze an image and compress it as much as possible without losing quality. With black-and-white comics, I could manually tweak the colors to shrink a 20MB image down to 300KB, but I don’t want to do that for each page since I’ve got hundreds, if not thousands, of images to process.
What are these images, and what do you plan to do with them now and in the future?
Basically, I’m just storing these images for now. If I ever need to use them in the future and they have some noise, I can run them through a resizing algorithm to clean them up. I’m not sure which ones are the best right now since it’s been a while, but those algorithms usually do a good job of removing noise without ruining the images.
I use XNView MP with stack and batch convert filters (such Enhance Focus) to obtain the best quality in the smallest amount of space. Needs some fine tuning, but overall I’m delighted with the outcome (for web publication). Remember to preserve the excellent sources in a secure location.