Data Sheet

CMOS VGA (640 x 480) image sensor with OmniPixel3-HS™ technology
OV7675/OV7175
proprietary to OmniVision Technologies PRODUCT SPECIFICATION version 2.0
5.6 color matrix
The color matrix is used to eliminate the cross talk induced by the micro-lens and color filter process. It also compensates
for lighting and temperature effects. Hue, color saturation, color space conversion from RGB to YUV/YCbCr can be also
combined with the color matrix.
The OV7675 matrix circuit is active in YUV/YCbCr and other formats are derived from YUV/YCbCr (refer to the equation
below).
where color matrix =
Since the Y signal is not from color matrix, the sensor generates Y signal from the original RGB directly. The color matrix
performs the color correction, RGB to YUV/YCbCr conversion, hue and color saturation control. Though the Y signal is
not from the color matrix, the calculation should be done by 3x3 matrix to get the combined matrix as shown below:
Combined Matrix = Saturation Matrix × Hue Matrix × Conversion Matrix × Correction Matrix
and then take the two rows for UV/CbCr as the final color matrix.
table 5-3 lists all the color matrix related registers. Each matrix element has 9 bits, 1 sign bit and 8 data bits. The register
value is equal to 128 times the real color matrix value.
table 5-3 color matrix related register and parameter
address register name reset value description
0x4F MTX1 0x40 Bit[7:0]: Matrix coefficient 1
0x50 MTX2 0x34 Bit[7:0]: Matrix coefficient 2
0x51 MTX3 0x0c Bit[7:0]: Matrix coefficient 3
0x52 MTX4 0x17 Bit[7:0]: Matrix coefficient 4
0x53 MTX5 0x29 Bit[7:0]: Matrix coefficient 5
0x54 MTX6 0x40 Bit[7:0]: Matrix coefficient 6
0x58 MTX_CTRL[5:0]
0x00
0x01
0x01
0x01
0x01
0x00
Sign Bit for Matrix Coefficient
Bit[5]: Sign bit for MTX6
Bit[4]: Sign bit for MTX5
Bit[3]: Sign bit for MTX4
Bit[2]: Sign bit for MTX3
Bit[1]: Sign bit for MTX2
Bit[0]: Sign bit for MTX1
or = ColorMatrix
V
U
R
G
B
Cr
Cb
MTX1
MTX4
MTX2
MTX5
MTX3
MTX6
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