int fosphor_gl_cmap_histogram(uint32_t *rgba, int N, void *arg)
int fosphor_gl_cmap_prog(uint32_t *rgba, int N, void *arg)
int fosphor_gl_cmap_png(uint32_t *rgba, int N, void *rsrc_name)
int fosphor_gl_cmap_waterfall(uint32_t *rgba, int N, void *arg)