tilt.cpp File Reference

#include <qimage.h>
#include <qstring.h>
#include <qapplication.h>
#include <math.h>
#include "tilt.h"
#include "tilt_internal.h"
#include "../../gui/statusWidget.h"

Include dependency graph for tilt.cpp:

Go to the source code of this file.

Functions
QImage *	correctImageTilt (QString filename, QPoint p1, QPoint p2, StatusWidget *status)
QRgb	interpolatedPixelValue (double xp, double yp, QImage *image)
QRgb	blendColors (QRgb color1, QRgb color2, double alpha)
DPoint	findTwoLineIntersection (DPoint p1, DPoint p2, DPoint p3, DPoint p4)

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Function Documentation

QRgb blendColors (  QRgb  color1, QRgb  color2, double  alpha )

Definition at line 359 of file tilt.cpp. Referenced by interpolatedPixelValue(). { double alpha2 = 1.0-alpha; return qRgb( (int) QMAX( QMIN( 255, alpha2*qRed (color1) + alpha*qRed(color2) ), 0 ), (int) QMAX( QMIN( 255, alpha2*qGreen(color1) + alpha*qGreen(color2) ), 0 ), (int) QMAX( QMIN( 255, alpha2*qBlue (color1) + alpha*qBlue(color2) ), 0 ) ); }

QImage* correctImageTilt (  QString  filename, QPoint  p1, QPoint  p2, StatusWidget *  status )

Definition at line 100 of file tilt.cpp. References bottomRight, editedImage, findTwoLineIntersection(), StatusWidget::incrementProgress(), interpolatedPixelValue(), newProgress, StatusWidget::setStatus(), StatusWidget::showProgressBar(), status, topLeft, updateIncrement, DPoint::x(), and DPoint::y(). Referenced by EditingInterface::finishCorrectTilt(). { //first compute distance between two points or "radius" int dx = p2.x() - p1.x(); int dy = p2.y() - p1.y(); //determine tilt angle int delta = 0; //compute recirpocal of distance between points double recip_r = 1.0 / sqrt( (double) (dx*dx + dy*dy) ); //compute angle with horizontal axis if( QABS(dx) > QABS(dy) ) { delta = dy; if(dx > 0) delta = -delta; } //compute angle with vertical axis else { delta = dx; if(dy < 0) delta = -delta; } double sinTheta = (delta * recip_r); double theta = asin( sinTheta ); double cosTheta = cos( theta ); //if angle is 0 (improbable but possible) then quit now if( theta == 0 ) return NULL; //load original and edited images QImage originalImage( filename ); //convert to 32-bit depth if necessary if( originalImage.depth() < 32 ) { originalImage = originalImage.convertDepth( 32, Qt::AutoColor ); } QImage rotatedImage( originalImage.width(), originalImage.height(), originalImage.depth() ); //setup progress bar QString statusMessage = qApp->translate( "correctImageTilt", "Correcting Tilt:" ); status->showProgressBar( statusMessage, 200 ); qApp->processEvents(); //during the first phase update the status bar for every 1% of image pixels that are processed int updateIncrement = (int) ( 0.01 * originalImage.width() * originalImage.height() ); int newProgress = 0; //set each pixel to the rotated value double xp, yp; double w2 = 0.5 * rotatedImage.width(); double h2 = 0.5 * rotatedImage.height(); int x,y; uchar* scanLine; QRgb* rgb; for( y=0; y<rotatedImage.height(); y++) { //iterate over each selected pixel in scanline scanLine = rotatedImage.scanLine(y); for( x=0; x<rotatedImage.width(); x++) { //compute unrotated coordinates xp = cosTheta*(x-w2) + sinTheta*(y-h2) + w2; yp = -sinTheta*(x-w2) + cosTheta*(y-h2) + h2; //set unrotated value rgb = ((QRgb*)scanLine+x); *rgb = interpolatedPixelValue( xp, yp, &originalImage); //update status bar if significant progress has been made since last update newProgress++; if(newProgress >= updateIncrement) { newProgress = 0; status->incrementProgress(); qApp->processEvents(); } } } //find rotated corners double nTheta = -theta; double sinNTheta = sin( nTheta ); double cosNTheta = cos( nTheta ); DPoint topLeft = DPoint( cosNTheta*(-w2) + sinNTheta*(-h2) + w2, -sinNTheta*(-w2) + cosNTheta*(-h2) + h2 ); DPoint topRight = DPoint( cosNTheta*(w2) + sinNTheta*(-h2) + w2, -sinNTheta*(w2) + cosNTheta*(-h2) + h2 ); DPoint bottomLeft = DPoint( cosNTheta*(-w2) + sinNTheta*(h2) + w2, -sinNTheta*(-w2) + cosNTheta*(h2) + h2 ); DPoint bottomRight = DPoint( cosNTheta*(w2) + sinNTheta*(h2) + w2, -sinNTheta*(w2) + cosNTheta*(h2) + h2 ); //determine which of these points are which in their rotated form DPoint top, bottom, left, right; if( theta < 0 ) { top = topRight; bottom = bottomLeft; left = topLeft; right = bottomRight; } else { top = topLeft; bottom = bottomRight; left = bottomLeft; right = topRight; } //construct true corners DPoint trueTopLeft ( 0, 0 ); DPoint trueTopRight ( rotatedImage.width()-1, 0 ); DPoint trueBottomLeft ( 0, rotatedImage.height()-1 ); DPoint trueBottomRight( rotatedImage.width()-1, rotatedImage.height()-1 ); //find intersections with image boundary DPoint topEdgeL = findTwoLineIntersection( left, top, trueTopLeft, trueTopRight ); DPoint topEdgeR = findTwoLineIntersection( top, right, trueTopLeft, trueTopRight ); DPoint bottomEdgeL = findTwoLineIntersection( left, bottom, trueBottomLeft, trueBottomRight ); DPoint bottomEdgeR = findTwoLineIntersection( bottom, right, trueBottomLeft, trueBottomRight ); DPoint leftEdgeT = findTwoLineIntersection( left, top, trueTopLeft, trueBottomLeft ); DPoint leftEdgeB = findTwoLineIntersection( left, bottom, trueTopLeft, trueBottomLeft ); DPoint rightEdgeT = findTwoLineIntersection( right, top, trueTopRight, trueBottomRight ); DPoint rightEdgeB = findTwoLineIntersection( right, bottom, trueTopRight, trueBottomRight ); //shot rays out from image center to each true corner and find intersections with clipped corners DPoint center( (int)w2, (int)h2 ); DPoint safeTopLeft = findTwoLineIntersection( center, trueTopLeft, leftEdgeT, topEdgeL ); DPoint safeTopRight = findTwoLineIntersection( center, trueTopRight, rightEdgeT, topEdgeR ); DPoint safeBottomLeft = findTwoLineIntersection( center, trueBottomLeft, leftEdgeB, bottomEdgeL ); DPoint safeBottomRight = findTwoLineIntersection( center, trueBottomRight, rightEdgeB, bottomEdgeR ); //find constrained area double minY = QMAX( safeTopLeft.y(), safeTopRight.y() ); double maxY = QMIN( safeBottomLeft.y(), safeBottomRight.y() ); double minX = QMAX( safeTopLeft.x(), safeBottomLeft.x() ); double maxX = QMIN( safeTopRight.x(), safeBottomRight.x() ); //find contrained area in integer coordinates. this is semi-tricky. //if the minimum values decimal porition is nonzero then increment by one // (eg 5.37 -> 6) int xMin = (int) minX; int xMax = (int) maxX; int yMin = (int) minY; int yMax = (int) maxY; if( xMin < minX ) xMin++; if( yMin < minY ) yMin++; //construct cropped rotated image QImage* editedImage = new QImage( xMax - xMin + 1, yMax - yMin + 1, rotatedImage.depth() ); //during the second phase update the status bar for every 1% of cropped pixels that are procesed updateIncrement = (int) ( 0.01 * editedImage->width() * editedImage->height() ); newProgress = 0; int x2,y2; uchar* scanLine2; QRgb* rgb2; y2 = 0; for( y=yMin; y<=yMax; y++, y2++) { //iterate over each selected pixel in scanline scanLine = rotatedImage.scanLine(y); scanLine2 = editedImage->scanLine(y2); x2 = 0; for( x=xMin; x<=xMax; x++, x2++) { rgb = ((QRgb*)scanLine +x ); rgb2 = ((QRgb*)scanLine2+x2); *rgb2 = *rgb; //update status bar if significant progress has been made since last update newProgress++; if(newProgress >= updateIncrement) { newProgress = 0; status->incrementProgress(); qApp->processEvents(); } } } //remove status bar status->setStatus( "" ); qApp->processEvents(); //return pointer to edited image return editedImage; }

DPoint findTwoLineIntersection (  DPoint  p1, DPoint  p2, DPoint  p3, DPoint  p4 )

Definition at line 367 of file tilt.cpp. References DPoint::x(), and DPoint::y(). Referenced by correctImageTilt(). { //---------------------------------------------- //=== Case 1: neither line has a change in X === //---------------------------------------------- //If there is no change in x for both lines, //either lines will NEVER or ALWAYS intersect. if(p1.x() == p2.x() && p4.x() == p3.x()) { //Ok, if their x values are equal, return //intersection point as line A's point A. //Yes, this is a little arbitratry. But //theoreticaly this section of code will almost //never be executed. if( p1.x() == p3.x() ) { return DPoint( p1.x(), p1.y() ); } //Else lines will never intersect, //return pair (-32000,-32000) else { return DPoint( -32000, -32000 ); } } //---------------------------------------------- //Else, we know at least one of the lines //does NOT have a slope of infinity!!! //---------------------------------------------- //---------------------------------------------- //=== Case 2: line A has no change in X === //---------------------------------------------- //If line A has an infinite slope (no change in x) //we know line B does not have an infinite slope... else if( p1.x() == p2.x() ) { double slopeB = ((double) (p4.y() - p3.y()) ) / (p4.x() - p3.x()); double yInterceptB = p3.y() - slopeB*p3.x(); //y = mx+b return DPoint( p2.x(), slopeB*p2.x() + yInterceptB ); } //---------------------------------------------- //=== Case 3: line B has no change in X === //---------------------------------------------- //If line B has an infinite slope (no change in x) //we know line A does not have an infinite slope... else if( p4.x() == p3.x() ) { double slopeA = ((double) (p2.y() - p1.y()) ) / (p2.x() - p1.x()); double yInterceptA = p1.y() - slopeA*p1.x(); //y = mx+b return DPoint( p4.x(), slopeA*p4.x() + yInterceptA ); } //---------------------------------------------- //=== Case 4: both lines have non infinite slopes === //---------------------------------------------- else { double slopeA = ((double) (p2.y() - p1.y()) ) / (p2.x() - p1.x()); double slopeB = ((double) (p4.y() - p3.y()) ) / (p4.x() - p3.x()); double yInterceptA = p1.y() - slopeA*p1.x(); double yInterceptB = p3.y() - slopeB*p3.x(); //y1 = mx1+b //y2 = nx2+c //at intersection y1=y2 and x1 = x2 so... //mx +b = nx + c //x(m-n) = c-b //x = (c-b)/(m-n) //where m and n are slope and //b and c are y-intercepts. //x = (c-b)/(m-n) double x = (yInterceptB - yInterceptA) / (slopeA - slopeB); return DPoint( x, (slopeA * x) + yInterceptA ); } }

QRgb interpolatedPixelValue (  double  xp, double  yp, QImage *  image )

Definition at line 312 of file tilt.cpp. References blendColors(). Referenced by correctImageTilt(). { //do boundary checking to //ensure we don't read beyond image boundaries if(xp < 0 || xp >= image->width() || yp < 0 || yp >= image->height() ) return qRgb( 0, 0, 0 ); //get four pixel colors, int x = (int)xp; int y = (int)yp; uchar* scanLine1 = image->scanLine( y ); uchar* scanLine2; if( y < image->height() - 1 ) scanLine2 = image->scanLine( y+1 ); else scanLine2 = scanLine1; QRgb p1,p2,p3,p4; p1 = *((QRgb*)scanLine1+x); p3 = *((QRgb*)scanLine2+x); if( x < image->width() - 1) { p2 = *((QRgb*)scanLine1+x+1); p4 = *((QRgb*)scanLine2+x+1); } else { p2 = p1; p4 = p3; } //blend four colors double alphaY = yp - y; double alphaX = xp - x; p1 = blendColors( p1, p2, alphaX ); p3 = blendColors( p3, p4, alphaX ); p1 = blendColors( p1, p3, alphaY ); return p1; }

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