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1 #+title: Fun with Gabor Filters
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2 #+author: Robert McIntyre
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3 #+email: rlm@mit.edu
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4 #+description: gabor filters in clojure with opencv
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5 #+keywords: computer vision, jMonkeyEngine3, clojure, opencv
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6 #+SETUPFILE: ../../aurellem/org/setup.org
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7 #+INCLUDE: ../../aurellem/org/level-0.org
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8 #+babel: :mkdirp yes :noweb yes :exports both
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9
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10
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11
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12 #+name: gabor
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13 #+begin_src clojure
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14 (ns cortex.gabor
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15 (:import org.opencv.core.CvType)
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16 (:import java.awt.image.BufferedImage)
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17 (:import ij.ImagePlus)
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18 (:import org.opencv.core.Mat)
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19 (:use cortex.sense)
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20 (:use cortex.util))
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21
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22 (defn load-opencv
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23 "Load the opencv native library. Must be called before any OpenCV
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24 stuff is used."
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25 []
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26 (clojure.lang.RT/loadLibrary "opencv_java249"))
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27
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28 (defn gabor-kernel [sigma aspect-ratio theta wavelength phase-offset]
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29
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30 ;; first, find the size of the kernel which is required
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31 (let [square #(expt % 2)
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32 rotated (fn [[x y]]
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33 [(+ (* x (Math/cos theta)) (* y (Math/sin theta)))
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34 (- (* y (Math/cos theta)) (* x (Math/sin theta)))])
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35
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36 gaussian (fn [[x y]]
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37 (let [[x' y'] (rotated [x y])]
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38 (Math/exp (- (/ (+ (square x')
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39 (square (* aspect-ratio y')))
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40 (* 2 (square sigma)))))))
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41 sinusoid (fn [[x y]]
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42 (let [[x' y'] (rotated [x y])]
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43 (Math/cos
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44 (+ (* 2 Math/PI (/ x' wavelength))
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45 phase-offset))))
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46
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47 half-width
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48 (let [std-dev-capture 5]
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49 (max
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50 (int (* std-dev-capture (/ sigma aspect-ratio)))
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51 (int (* std-dev-capture sigma))
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52 (int (* std-dev-capture (/ aspect-ratio sigma)))))
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53
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54 grid (let [axis (range (- half-width) (inc half-width))]
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55 (for [y (reverse axis) x axis] (vector x y)))
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56
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57 scale (reduce + (map gaussian grid))
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58
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59 gabor (fn [[x y :as coord]]
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60 (* (sinusoid coord) (gaussian coord) (/ scale)))
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61
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62 mat-width (+ 1 (* 2 half-width))
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63 mat (Mat. mat-width mat-width CvType/CV_32F)]
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64
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65 (.put mat 0 0 (float-array (map gabor grid)))
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66 mat))
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67
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68
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69 (defn draw-kernel! [kernel img-path]
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70 (let [output img-path
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71 size (.size kernel)
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72 width (int (.width size))
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73 height (int (.height size))
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74 tmp-array (float-array (* width height))]
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75
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76 ;; read values from matrix.
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77 (.get kernel 0 0 tmp-array)
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78
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79 ;; find overall dynamic range of the filter
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80 (let [vals (vec tmp-array)
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81 low (apply min vals)
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82 high (apply max vals)
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83 scaled-vals (map #(* 255 (- % low) (/ (- high low))) vals)
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84 new-mat (Mat. height width CvType/CV_32F)]
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85 (.put new-mat 0 0 (float-array scaled-vals))
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86 (org.opencv.highgui.Highgui/imwrite output new-mat))))
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87
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88 (defn show-kernel [kernel]
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89 (let [img-path "/home/r/proj/cortex/tmp/kernel.png"]
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90 (draw-kernel! kernel img-path)
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91 (view (ImagePlus. output))))
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92
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93 (defn print-kernel [kernel]
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94 (println (.dump kernel)))
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95
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96 (defn convolve-practice []
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97 (let [input "/home/r/proj/cortex/images/dominos.jpg"
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98
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99
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100 output "/home/r/ppp.png"
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101
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102 i (org.opencv.highgui.Highgui/imread input)
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103
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104 kernel (gabor-kernel 10 1 (/ Math/PI 2) 10 0)
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105
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106 new-mat (Mat.)
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107
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108 ]
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109
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110 (org.opencv.imgproc.Imgproc/filter2D i new-mat CvType/CV_32F kernel)
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111
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112 (org.opencv.highgui.Highgui/imwrite "/home/r/ppp.png" new-mat)
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113
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114 (view (ImagePlus. input))
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115 (view (ImagePlus. output))))
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116
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117 #+end_src
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118
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119
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120
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121 * COMMENT Generate Source
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122 #+begin_src clojure :tangle ../src/cortex/gabor.clj
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123 <<gabor>>
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124 #+end_src
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