130 lines
2.9 KiB
Matlab
130 lines
2.9 KiB
Matlab
#! /usr/bin/env octave
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cv;
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highgui;
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file_name = "../c/baboon.jpg";
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global Gbrightness;
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global Gcontrast;
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global hist_size;
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global ranges;
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global src_image;
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global dst_image;
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global hist_image;
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global hist;
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global lut;
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_brightness = 100;
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_contrast = 100;
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Gbrightness = 100;
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Gcontrast = 100;
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hist_size = 64;
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range_0={0,256};
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ranges = { range_0 };
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src_image=[];
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dst_image=[];
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hist_image=[];
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hist=[];
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lut=cvCreateMat(256,1,CV_8U);
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## brightness/contrast callback function
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function update_brightness( val )
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global Gbrightness # global tag is required, or we get UnboundLocalError
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Gbrightness = val;
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update_brightcont( );
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endfunction
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function update_contrast( val )
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global Gcontrast; # global tag is required, or we get UnboundLocalError
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Gcontrast = val;
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update_brightcont( );
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endfunction
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function update_brightcont()
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global Gbrightness;
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global Gcontrast;
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global hist_size;
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global ranges;
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global src_image;
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global dst_image;
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global hist_image;
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global hist;
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global lut;
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global cvCalcHist; # use cv namespace for these instead
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global cvZero;
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global cvScale;
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brightness = Gbrightness - 100;
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contrast = Gcontrast - 100;
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max_value = 0;
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## The algorithm is by Werner D. Streidt
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## (http://visca.com/ffactory/archives/5-99/msg00021.html)
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if( contrast > 0 )
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delta = 127.*contrast/100;
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a = 255./(255. - delta*2);
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b = a*(brightness - delta);
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else
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delta = -128.*contrast/100;
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a = (256.-delta*2)/255.;
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b = a*brightness + delta;
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endif
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for i=0:256-1,
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v = cvRound(a*i + b);
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if( v < 0 )
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v = 0;
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endif
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if( v > 255 )
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v = 255;
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endif
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lut(i) = v;
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endfor
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cvLUT( src_image, dst_image, lut );
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cvShowImage( "image", dst_image );
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cvCalcHist( dst_image, hist, 0, [] );
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cvZero( dst_image );
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[min_value, max_value] = cvGetMinMaxHistValue( hist );
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cvScale( hist.bins, hist.bins, double(hist_image.height)/max_value, 0 );
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##cvNormalizeHist( hist, 1000 );
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cvSet( hist_image, cvScalarAll(255));
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bin_w = cvRound(double(hist_image.width)/hist_size);
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for i=0:hist_size-1,
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cvRectangle( hist_image, cvPoint(i*bin_w, hist_image.height), cvPoint((i+1)*bin_w, hist_image.height - cvRound(cvGetReal1D(hist.bins,i))), cvScalarAll(0), -1, 8, 0 );
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endfor
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cvShowImage( "histogram", hist_image );
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endfunction
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## Load the source image. HighGUI use.
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if size(argv, 1)>1
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file_name = argv(){1}
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endif
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src_image = cvLoadImage( file_name, 0 );
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if (!swig_this(src_image))
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printf("Image was not loaded.\n");
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exit(-1);
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endif
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dst_image = cvCloneImage(src_image);
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hist_image = cvCreateImage(cvSize(320,200), 8, 1);
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hist = cvCreateHist({hist_size}, CV_HIST_ARRAY, ranges, 1);
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cvNamedWindow("image", 0);
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cvNamedWindow("histogram", 0);
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cvCreateTrackbar("brightness", "image", _brightness, 200, @update_brightness);
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cvCreateTrackbar("contrast", "image", _contrast, 200, @update_contrast);
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update_brightcont();
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cvWaitKey(0);
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