SUB2r camera starts supporting CCM (a.k.a. CMX) with FX3 v. 58 and FPGA v. 73.

With the OV10823 OmniVision image sensor we use the “standard” Bayer pattern that looks like this:

Color Correction Matrix is often used as an “add-on” matrix during YUV→RGB conversion. In our case, since the de-bayering and RGB→YUV conversions happen literally on opposite sides of the imaging pipeline, we only use the portion of the corrections designed to compensate for the sensor's cross-talk, converting pre-debayer values \(R_0, Gr_0, Gb_0, B_0\) into \(R, Gr, Gb, B\) that are then used for conversion into RGB:

\[ \begin{bmatrix} B & Gb & Gr & R\end{bmatrix} = \begin{bmatrix} CCM_{00} & CCM_{01} & CCM_{02} & CCM_{03} \\ CCM_{10} & CCM_{11} & CCM_{12} & CCM_{13} \\ CCM_{20} & CCM_{21} & CCM_{22} & CCM_{23} \\ CCM_{30} & CCM_{31} & CCM_{32} & CCM_{33} \end{bmatrix} \cdot \begin{bmatrix} B_0 \\ Gb_0 \\ Gr_0 \\ R_0 \end{bmatrix} \]

In this matrix \(Gb_0\) is a value of “green pixel in a blue row” (i.e. in a B-G-B-G-B-… row) and, similarly, \(Gr_0\) is a value of “green pixel in a red row”.

The matrix is applied to a \(2\times2\) block of \(\begin{bmatrix}B_0 & Gb_0 \\ Gr_0 & R_0\end{bmatrix}\) values represented by a “flattened out” vector \(\begin{bmatrix}B_0 & Gb_0 & Gr_0 & R_0\end{bmatrix}\).