I'm currently working on a pixel art game with a 2d tile map and I am aware that to stop texture bleeding you need to pad out each tile. I also find the best result if you pad out each tile by 'stretching' its edge. For example:

becomes -------->

However, to me, padding out each tile manually is a bit tedious and also makes the tilesheet harder to edit since you need to remember to re-pad every time. I'm wondering if there is any software out there which can take in a tilesheet and do all the padding for you?

I'd prefer to edit the tilesheet all in one place rather than edit tiles separately and pack them together. Or is there some way of storing each tile separately but editing them together as though they were in a single tilesheet, and then using a texture packer to pack them together and do everything you need to do for the padding?