Notes The DXT1 formats require either the GL_EXT_texture_compression_s3tc or GL_EXT_texture_compression_dxt1 extension. The other DXT formats require the GL_EXT_texture_compression_s3tc extension. The LATC formats require the GL_EXT_texture_compression_latc extension. The RGTC formats require OpenGL 3.0 or later or the GL_EXT_texture_compression_rgtc extension.