def im_detect_mask_aspect_ratio(model, im, aspect_ratio, boxes, hflip=False):
    """Computes mask detections at the given width-relative aspect ratio."""

    # Perform mask detection on the transformed image
    im_ar = image_utils.aspect_ratio_rel(im, aspect_ratio)
    boxes_ar = box_utils.aspect_ratio(boxes, aspect_ratio)

    if hflip:
        masks_ar = im_detect_mask_hflip(
            model, im_ar, cfg.TEST.SCALE, cfg.TEST.MAX_SIZE, boxes_ar
        )
    else:
        im_scale = im_conv_body_only(
            model, im_ar, cfg.TEST.SCALE, cfg.TEST.MAX_SIZE
        )
        masks_ar = im_detect_mask(model, im_scale, boxes_ar)

    return masks_ar
Computes mask detections at the given width-relative aspect ratio.
detectron/core/test.py