0xa6, 0xb2, 0xbf, 0xca, 0xd5, 0xe0, 0xeb, 0xf5, 0xff
 };
 
+/* color matrix and offsets */
 static const __u8 reg84[] = {
-       0x14, 0x00, 0x27, 0x00, 0x07, 0x00, 0xe5, 0x0f,
-       0xe4, 0x0f, 0x38, 0x00, 0x3e, 0x00, 0xc3, 0x0f,
-       0xf7, 0x0f, 0x00, 0x00, 0x00
+       0x14, 0x00, 0x27, 0x00, 0x07, 0x00,     /* YR YG YB gains */
+       0xe8, 0x0f, 0xda, 0x0f, 0x40, 0x00,     /* UR UG UB */
+       0x3e, 0x00, 0xcd, 0x0f, 0xf7, 0x0f,     /* VR VG VB */
+       0x00, 0x00, 0x00                        /* YUV offsets */
 };
 static const __u8 hv7131r_sensor_init[][8] = {
        {0xC1, 0x11, 0x01, 0x08, 0x01, 0x00, 0x00, 0x10},
 static void setbrightcont(struct gspca_dev *gspca_dev)
 {
        struct sd *sd = (struct sd *) gspca_dev;
-       unsigned val;
+       int val;
        __u8 reg84_full[0x15];
 
-       memset(reg84_full, 0, sizeof reg84_full);
-       val = sd->contrast * 0x20 / CONTRAST_MAX + 0x10;        /* 10..30 */
-       reg84_full[2] = val;
-       reg84_full[0] = (val + 1) / 2;
-       reg84_full[4] = (val + 1) / 5;
-       if (val > BRIGHTNESS_DEF)
-               val = (sd->brightness - BRIGHTNESS_DEF) * 0x20
+       memcpy(reg84_full, reg84, sizeof reg84_full);
+       val = sd->contrast * 0x30 / CONTRAST_MAX + 0x10;        /* 10..40 */
+       reg84_full[0] = (val + 1) / 2;          /* red */
+       reg84_full[2] = val;                    /* green */
+       reg84_full[4] = (val + 1) / 5;          /* blue */
+       val = (sd->brightness - BRIGHTNESS_DEF) * 0x10
                        / BRIGHTNESS_MAX;
-       else
-               val = 0;
-       reg84_full[0x12] = val;                 /* 00..1f */
+       reg84_full[0x12] = val & 0x1f;          /* 5:0 signed value */
        reg_w(gspca_dev, 0x84, reg84_full, sizeof reg84_full);
 }