scaleFromLetterbox function

List<double> scaleFromLetterbox(List<double> xyxy, double ratio, int dw, int dh,)

Transforms bounding box coordinates from letterbox space back to original image space.

Reverses the letterbox transformation by removing padding and unscaling coordinates.

Parameters:

• xyxy: Bounding box in letterbox space as [x1, y1, x2, y2]
• ratio: Scale ratio from letterbox preprocessing
• dw: Horizontal padding from letterbox preprocessing
• dh: Vertical padding from letterbox preprocessing

Returns the bounding box in original image space as [x1, y1, x2, y2].

Implementation

List<double> scaleFromLetterbox(
  List<double> xyxy,
  double ratio,
  int dw,
  int dh,
) {
  final double x1 = (xyxy[0] - dw) / ratio;
  final double y1 = (xyxy[1] - dh) / ratio;
  final double x2 = (xyxy[2] - dw) / ratio;
  final double y2 = (xyxy[3] - dh) / ratio;
  return [x1, y1, x2, y2];
}