I'm not sure if this has been done yet or not, but I spent all night on this so here goes. This is an upgraded version of Minecraft's 'art' texture, kz.png, which contains the textures used for paintings. Using the painting article on mcwiki as a reference, I've recreated the default painting layout (including the five composite ones) in wonderful HD, in sizes of 128, 64, and 32. Most are simple scale and crops, but a few took a considerable amount of effort to create, ie the flowers on the windowsill, and the blue 2x2 skull. I've also removed the frames, allowing a bit more detail to show; if you bug me enough, I might add them back in though this way looks better me thinks.
The following download includes 3 sizes of the image; to use it, just rename the one you want to keep 'kz.png', and move it to your texture packs 'Art' Folder. Because trying to do the same thing I did would yield practically identical results, I'm allowing any pack authors to include it in your own projects, a la GPL.
The difference between me and misa's, is that I've gone and replicated all 5 'composite' paintings, i.e. ones that vary from the 'originals'. Specifically, Mine recreates (with a little bit of artistic license) the blue skull, the spider, and the flower on windowsill; I also did the creeper window and pig on paper that misa does, with slightly better results (I use the modified pig, for example). Additionally, his version only goes up to 64x, whereas mine goes up to 128x. Finally, mine includes the new 'flaming skull' texture. Here's a select comparison:
For some reason when I use this on my texture pack I've been working on all summer it crashes minecraft. This is extremely depressing because I was so excited to use it as a template. I only replaced one painting so far but Idk why it crashes minecraft. Please help if you can or if you've heard anything about it before. I've already credited you in the Texture pack and I'd hate to have to take it out.
Edit: I was wondering if it was because I was using a non HD pack with an HD art template? I'm not sure because everything comes up and then the screen goes Minecraft Sky Blue. I tried all of them and could only get it to work with the 32 =( Let me know ASAP if you have a solution please.