void(* shrink[4])(uint8_t *dst, int dst_wrap, const uint8_t *src, int src_wrap, int width, int height)
void(* draw_edges)(uint8_t *buf, int wrap, int width, int height, int w, int h, int sides)
int(* pix_norm1)(uint8_t *pix, int line_size)
int(* pix_sum)(uint8_t *pix, int line_size)
main external API structure.
void(* add_8x8basis)(int16_t rem[64], int16_t basis[64], int scale)
int(* try_8x8basis)(int16_t rem[64], int16_t weight[64], int16_t basis[64], int scale)