SPRUJ28F November 2021 – August 2025 AM68 , AM68A , TDA4AL-Q1 , TDA4VE-Q1 , TDA4VL-Q1
The WB CSC unit converts the encoded pixel values from RGB48 into YUV444 format. For YUV420 or YUV422 as output formats, a chrominance subsampling (YUV444 to YUV422, and YUV422 to YUV420) is performed in the WB scaler block afer the CSC operation.
Figure 12-358 and Figure 12-359 show the 3 × 3 11-bit coefficients used for the CSC operation. The user sets the coefficients according to the standard used to encode the pixel data in YUV color space. Table 12-344 lists the coefficients with their respective bit fields, together with the post offsets (that are 13-bit signed integer numbers).
| Coefficients | Register Bit Fields |
|---|---|
| YR | DSS0_WB_CSC_COEF0[10:0] C00 |
| YG | DSS0_WB_CSC_COEF0[26:16] C01 |
| YB | DSS0_WB_CSC_COEF1[10:0] C02 |
| CrR | DSS0_WB_CSC_COEF1[26:16] C10 |
| CrG | DSS0_WB_CSC_COEF2[10:0] C11 |
| CrB | DSS0_WB_CSC_COEF2[26:16] C12 |
| CbR | DSS0_WB_CSC_COEF3[10:0] C20 |
| CbG | DSS0_WB_CSC_COEF3[26:16] C21 |
| CbB | DSS0_WB_CSC_COEF4[10:0] C22 |
| RPOSTOFFSET | DSS0_WB_CSC_COEF6[31-19] POSTOFFSET1 |
| GPOSTOFFSET | DSS0_WB_CSC_COEF7[15-3] POSTOFFSET2 |
| BPOSTOFFSET | DSS0_WB_CSC_COEF7[31-19] POSTOFFSET3 |
Limited data range conversion (video data range)
If the active range for the 12-bit output luminance samples (Y) is to be [256:3760] and for the output chrominance samples (Cb and Cr) is to be [256:3840], then Figure 12-358 gives the equation (based on 11-bit coefficients) to convert the RGB to YUV. The range selection is done by setting the DSS0_WB_ATTRIBUTES[11] FULLRANGE bit to 0x0. The [256, 2048, 2048] offset values are programmable through the registers from Table 12-344.
Figure 12-358 DISPC WB CSC RGB to YCbCr Equation (Limited Data Range), 12-bit OutputsFull data range conversion (graphics data range)
If the active range for the output luminance samples (Y) and or the chrominance samples (Cb and Cr) is [0:4095], then Figure 12-359 gives the equation (based on 11-bit coefficients) to convert the RGB to YUV. The [0, 2048, 2048] offset values are programmable through the registers from Table 12-344.
Figure 12-359 DISPC WB CSC RGB to YCbCr Equation (Full Data Range), 12-bit Outputs