contrast.h File Reference

This graph shows which files directly or indirectly include this file:

Go to the source code of this file.

Functions
QImage *	enhanceImageContrast (QString filename, StatusWidget *status)
void	enhanceImageContrast (QImage *image, StatusWidget *status=NULL)

---

Function Documentation

void enhanceImageContrast (  QImage *  editedImage, StatusWidget *  status )

------ Contrast stretching - http://www.ph.tn.tudelft.nl/Courses/FIP/frames/fip-istogram.html ------- Definition at line 105 of file contrast.cpp. References b, editedImage, HSVtoRGB(), StatusWidget::incrementProgress(), newProgress, RGBtoHSV(), RGBtoL(), StatusWidget::setStatus(), StatusWidget::showProgressBar(), status, and updateIncrement. Referenced by EdgeDetect::constructEdgeImage(), EditingInterface::enhanceContrast(), and enhanceImageContrast(). { //setup progress bar if(status) { QString statusMessage = qApp->translate( "enhanceImageContrast", "Enhancing Contrast:" ); status->showProgressBar( statusMessage, 100 ); qApp->processEvents(); } //update progress bar for every 1% of completion const int updateIncrement = (int) ( 0.01 * editedImage->width() * editedImage->height() ); int newProgress = 0; //construct intensity histograph int grayVals[256]; int i=0; for(i=0; i<256; i++) { grayVals[i] = 0; } //populate histogram by iterating over all image pixels int numPixels = editedImage->width()*editedImage->height(); QRgb* rgb; double grayValue; uchar* scanLine; int x, y; for( y=0; y<editedImage->height(); y++) { //iterate over each selected pixel in scanline scanLine = editedImage->scanLine(y); for( x=0; x<editedImage->width(); x++) { rgb = ((QRgb*)scanLine+x); grayValue = RGBtoL(rgb); grayVals[(int)grayValue]++; } //for x } //for y //find 1% and 99% precenticles //we'll stretch these values so we avoid outliers from affecting the stretch int sum=0; double indexLow, indexHigh; indexLow = -1.0; indexHigh = -1.0; for(i=0; i<256; i++) { sum+=grayVals[i]; //if 1% not found yet and criteria met set index if(indexLow < 0 && sum >= 0.01*numPixels) { indexLow = ((double)i)/255.0; } //if 99% not found yet and criteria met set index if(indexHigh < 0 && sum >= 0.99*numPixels) { indexHigh = ((double)i)/255.0; } } //only apply scaling if indexHigh > indexLow if(indexHigh > indexLow) { //run through all image pixels a second time, this time scaling coordinates as necessary for( y=0; y<editedImage->height(); y++) { //iterate over each selected pixel in scanline scanLine = editedImage->scanLine(y); for( x=0; x<editedImage->width(); x++) { //get color coordinates and convert to 0-1 scale rgb = ((QRgb*)scanLine+x); double r = ((double)qRed(*rgb) )/255.0; double g = ((double)qGreen(*rgb) )/255.0; double b = ((double)qBlue(*rgb) )/255.0; //convert to hsv double h,s,v; RGBtoHSV(r,g,b,&h,&s,&v); //scale and clamp v v = (v-indexLow)/(indexHigh-indexLow); //convert adjusted color back to rgb colorspace and clamp HSVtoRGB( &r,&g,&b, h,s,v); int rp = (int) QMIN( QMAX((r*255), 0), 255 ); int gp = (int) QMIN( QMAX((g*255), 0), 255 ); int bp = (int) QMIN( QMAX((b*255), 0), 255 ); //set adjusted color value *rgb = qRgb(rp,gp,bp); //update status bar if significant progress has been made since last update if(status) { newProgress++; if(newProgress >= updateIncrement) { newProgress = 0; status->incrementProgress(); qApp->processEvents(); } } } //for x } //for y } //if scaling should be preforemd //remove status bar if(status) { status->setStatus( "" ); qApp->processEvents(); } }

QImage* enhanceImageContrast (  QString  filename, StatusWidget *  status )

Definition at line 85 of file contrast.cpp. References editedImage, enhanceImageContrast(), and status. { //load original image QImage* editedImage = new QImage( filename ); //convert to 32-bit depth if necessary if( editedImage->depth() < 32 ) { QImage* tmp = editedImage; editedImage = new QImage( tmp->convertDepth( 32, Qt::AutoColor ) ); delete tmp; tmp=NULL; } //enhance contrast enhanceImageContrast( editedImage, status ); //return pointer to edited image return editedImage; }

---