Procedural animated texture generation/Fire
Detailed information is limited, however an implementation has been made in MC-TextureGen: https://github.com/NeRdTheNed/MC-TextureGen/blob/main/mc-texture-gen-impl/src/main/java/com/github/nerdthened/mctexturegen/generators/FireGenerator.java
The generated texture is 16x20; the bottom 4 pixels are cropped, leaving a 16x16 texture.