getRgbBuffer(src, srcOffset, count, dest, destOffset, bits, alpha01) {
    unreachable("Should not call ColorSpace.getRgbBuffer");
  }
Converts the specified number of the color values to the RGB colors.
The colors are located in the src array starting from the srcOffset.
The result is placed into the dest array starting from the destOffset.
The src array items shall be in [0,2^bits) range, the dest array items
will be in [0,255] range. alpha01 indicates how many alpha components
there are in the dest array; it will be either 0 (RGB array) or 1 (RGBA
array).