Importing very small textures causes weird rounding.

I'm trying to make a doom-like game with billboarded sprites and very big pixels, and I'm trying to import very small textures, 64x64, to use for the sprites. When I create a material from the small .PNG's, Unity does some weird rounding on the pixels and a lot of the shading detail is lost. When I blow the sprite up in Photoshop to 1024x1024 everything looks right, but it seems stupid and a waste of time to blow all our sprites up to a huge size when we're going for the retro-pixelated effect.

Any suggestions?

turn off filters like blinear and turn off mipmapping. the most important setting that you should turn off is filtering. test the mipmap setting enabled/disabled.

Thanks for the tips, I found out mine were all weird unless you set the filter mode to point. Thanks!