M_SOF1           2138 ext/exif/exif.c #define M_SOF1  0xC1    /* N indicates which compression process   */
M_SOF1            319 ext/standard/image.c #define M_SOF1  0xC1			/* N indicates which compression process */
M_SOF1             44 ext/standard/iptc.c #define M_SOF1  0xC1            /* N indicates which compression process */