I have a huge 8 bit B&W image (PNG, 200k x 100k px) which is a high resolution generated map of a large area, so I can't generate it in small chunks. The map is fine, Photoshop CC 19 (Windows 10) handles it great, but I now need to slice it into 8192 x 8192 px tiles, and I'm having no luck. Nothing in the "save as" dialog, nor anything apparently relevant in the "export as" dialog, and "save for web" is greyed out and I can't figure why.
Clean install, from Adobe installer, no messing round or extensions. I've got as far as an image with slices/tiles shown correctly in blue (and unwanted slices/tiles deleted), but can't seem to get it to do anything with them.
I've even tried as Adobe says, selecting a tile and edit->copy (to paste into another tab or even MS Paint), but it copies the entire image, not just the content of that tile.
I tried using ImageMagick instead, but it failed with a "can't access magic.xml" error for reasons I don't understand, so I'm back trying to slice it in Photoshop.
Any ideas, workarounds, or similar, whatsoever? Speed is key - all I need to do is slice, but I've got to upload them for a presentation tomorrow morning! :)