How to use single image in tilemap?

I am developing a 2d game,and stuck in how to manager nearly 1 million images,I think it is hard to merge these images to tileset.If I can put single image to tilemap then it will be easy to write code.or these is any other way to do this.

Thank you for your reply,I have already tried TexturePacker,but it is still hard to mergy so much images.So, shall I create a lot of tileset? Each one may have 2000 images in it.

try to split up the images based on whether they need to be loaded into memory at the same time. for example, snow props and jungle props should be on separate sprite sheets, since only 1 of those tilesets would need to be loaded at a time. if you have an enemy that only exists in the snow area, you could include their sprites in that snow props sheet. if you have an enemy that could exist in both levels, then it should be on a separate tile set, maybe along with other common enemies.

its a balance between loading only what you need, and trying not to load and unload assets so often that it hurts performance. if you separated every sprite into its own image, you would be using ram efficiently, only loading what is needed, but all that constant loading might hurt performance. the opposite strategy is to put everything into a single large file, which would keep everything loaded at all times. the ideal strategy is some mix of the two, grouping things that fit together, and separating data that only needs to be loaded rarely.