I would consider the “source code” for artwork to be the project file, with all of the layers intact and whatnot. The Photoshop PSD, the GIMP XCF or the Krita KRA. The “compiled” version would be the exported PNG/JPG.
You can license a compiled binary under CC BY if you want. That would allow users to freely decompile/disassemble it or to bundle the binary for their purposes, but it’s different from releasing source code. It’s closed source, but under a free license.
I would consider the “source code” for artwork to be the project file, with all of the layers intact and whatnot. The Photoshop PSD, the GIMP XCF or the Krita KRA. The “compiled” version would be the exported PNG/JPG.
You can license a compiled binary under CC BY if you want. That would allow users to freely decompile/disassemble it or to bundle the binary for their purposes, but it’s different from releasing source code. It’s closed source, but under a free license.