阴影检测

检测强阴影 S2，处理弱阴影 S_B

``` matlab
imgFile = '%datasets\KITTI\data_road\training\image_2\uu_000083.png';
% uu_000083
% um_000008
Raw = RawImg(imgFile);
ROI = Raw.rectroi({ceil(Raw.rows/2):Raw.rows,1:Raw.cols});
S2 = vvFeature.Slog(Raw.data);

% first do road marking remval, then do S2 feature extraction

Fig.subimshow(S2);return;
```