chapter09directionfiltering.pro

idl 可视化分析与应用（随书程序）

; Chapter09DirectionFiltering.pro
PRO Chapter09DirectionFiltering
  file = FILEPATH('nyny.dat', SUBDIRECTORY = ['examples', 'data'])
  imageSize = [768, 512]
  image = READ_BINARY(file, DATA_DIMS = imageSize)
  croppedSize = [96, 96]
  croppedImage = image[200:(croppedSize[0] - 1) + 200, $
    180:(croppedSize[1] - 1) + 180]
  DEVICE, DECOMPOSED = 0
  LOADCT, 0
  displaySize = [256, 256]
  WINDOW, 0, XSIZE = displaySize[0], YSIZE = displaySize[1], $
    TITLE = 'Cropped New York Image'
  TVSCL, CONGRID(croppedImage, displaySize[0], displaySize[1])
  kernelSize = [3, 3]
  kernel = FLTARR(kernelSize[0], kernelSize[1])
  kernel[0, *] = -1.
  kernel[2, *] = 1.
  filteredImage = CONVOL(FLOAT(croppedImage), kernel, $
    /CENTER, /EDGE_TRUNCATE)
  WINDOW, 1, XSIZE = displaySize[0], YSIZE = displaySize[1], $
    TITLE = 'Direction Filtered New York Image'
  TVSCL, CONGRID(filteredImage, displaySize[0], displaySize[1])
  WINDOW, 2, XSIZE = displaySize[0], YSIZE = displaySize[1], $
    TITLE = 'Slopes of Direction Filtered New York Image'
  TVSCL, CONGRID(-1 > FIX(filteredImage/50) < 1, displaySize[0], $
    displaySize[1])
END