Function chess_response_u8_patch 

pub fn chess_response_u8_patch(
    img: &[u8],
    img_w: usize,
    img_h: usize,
    params: &ChessParams,
    roi: Roi,
) -> ResponseMap

Compute the ChESS response only inside a rectangular ROI of the image.

The ROI is given in image coordinates [x0, x1) × [y0, y1) via Roi. The returned ResponseMap has width (x1 - x0) and height (y1 - y0), with coordinates relative to (x0, y0).

Pixels where the ChESS ring would go out of bounds (w.r.t. the full image) are left at 0.0, and will be ignored by the detector because they lie inside the border margin. Internally this reuses the same scalar, SIMD, and optional rayon row kernels as chess_response_u8, so ROI refinement benefits from the same feature combinations as the full-frame response path.