title: Image resize vs Image pyramid for generating ROI for pedestrian detection - OpenCV
body: <p>For a OpenCV driving assistance application I want to generate ROIs as candidates for faster HoG classification of pedestrians. I'm running this on GPU. I do not want to use detectMultiscale function as it scan all over the image (including sky). Since the features are not scalable, which of the following functions I should use for resizing the images for generating the ROIs? </p>
  
  <p>gpu::resize(const GpuMat&amp; src, GpuMat&amp; dst, Size dsize, double fx=0, double fy=0, int interpolation=INTER_LINEAR, Stream&amp; stream=Stream::Null()) or </p>
  
  <p>Image pyramids cv2.pyrUp(), cv2.pyrDown() </p>
  
  <p>I couldn't find image pyramids in OpenCV GPU library(2.4.9).</p>
  
  <p>Can anyone please suggest?</p>
  
  <p>Thanks</p>