I think it's PS but it should be fairly easily translatable. It's a good tut for blending and composition, and making textures work. This is it.
What I do is I duplicate the layers and I set the duplicate layers to screen to brighten up the darker images lower quality images from s1. I’ll do this a couple of times until I have a better/brighter image. But also, there are HD screencaps for s1 and some of s2 here (thanks to @Jam ). She is working in another project but she may go back and screen cap the rest of BtVS in HD later so keep checking back for updates.
Not the best, the image quality for season 1 isn't very good