2 #pragma package <opencv>
11 char file_name[] = "baboon.jpg";
13 int _brightness = 100;
17 float range_0[]={0,256};
18 float* ranges[] = { range_0 };
19 IplImage *src_image = 0, *dst_image = 0, *hist_image = 0;
24 /* brightness/contrast callback function */
25 void update_brightcont( int arg )
27 int brightness = _brightness - 100;
28 int contrast = _contrast - 100;
33 * The algorithm is by Werner D. Streidt
34 * (http://visca.com/ffactory/archives/5-99/msg00021.html)
38 double delta = 127.*contrast/100;
39 double a = 255./(255. - delta*2);
40 double b = a*(brightness - delta);
41 for( i = 0; i < 256; i++ )
43 int v = cvRound(a*i + b);
53 double delta = -128.*contrast/100;
54 double a = (256.-delta*2)/255.;
55 double b = a*brightness + delta;
56 for( i = 0; i < 256; i++ )
58 int v = cvRound(a*i + b);
67 cvLUT( src_image, dst_image, lut_mat );
68 cvShowImage( "image", dst_image );
70 cvCalcHist( &dst_image, hist, 0, NULL );
72 cvGetMinMaxHistValue( hist, 0, &max_value, 0, 0 );
73 cvScale( hist->bins, hist->bins, ((double)hist_image->height)/max_value, 0 );
74 /*cvNormalizeHist( hist, 1000 );*/
76 cvSet( hist_image, cvScalarAll(255), 0 );
77 bin_w = cvRound((double)hist_image->width/hist_size);
79 for( i = 0; i < hist_size; i++ )
80 cvRectangle( hist_image, cvPoint(i*bin_w, hist_image->height),
81 cvPoint((i+1)*bin_w, hist_image->height - cvRound(cvGetReal1D(hist->bins,i))),
82 cvScalarAll(0), -1, 8, 0 );
84 cvShowImage( "histogram", hist_image );
88 int main( int argc, char** argv )
90 // Load the source image. HighGUI use.
91 src_image = cvLoadImage( argc == 2 ? argv[1] : file_name, 0 );
95 printf("Image was not loaded.\n");
99 dst_image = cvCloneImage(src_image);
100 hist_image = cvCreateImage(cvSize(320,200), 8, 1);
101 hist = cvCreateHist(1, &hist_size, CV_HIST_ARRAY, ranges, 1);
102 lut_mat = cvCreateMatHeader( 1, 256, CV_8UC1 );
103 cvSetData( lut_mat, lut, 0 );
105 cvNamedWindow("image", 0);
106 cvNamedWindow("histogram", 0);
108 cvCreateTrackbar("brightness", "image", &_brightness, 200, update_brightcont);
109 cvCreateTrackbar("contrast", "image", &_contrast, 200, update_brightcont);
111 update_brightcont(0);
114 cvReleaseImage(&src_image);
115 cvReleaseImage(&dst_image);
117 cvReleaseHist(&hist);