jit.pix is treats its inputs and outputs as ARGB data. you can see this easily by unpacking the matrix coming out. Internally the data is treated as RGBA, which you can determine by swizing the color planes and looking at the output data, as well as looking at the code window (e.g. swiz 0 == swiz.r and swiz 3 == swiz.a)

confusing I know, but that's how you can use gl.pix gen patchers interchangeably with pix gen patchers.