137 lines
3.2 KiB
C++
137 lines
3.2 KiB
C++
#include "histogram.h"
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#include <QDebug>
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#include <QPainter>
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#include <cmath>
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Histogram::Histogram(QImage* image)
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{
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R = new QHash<int, int>;
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G = new QHash<int, int>;
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B = new QHash<int, int>;
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L = new QHash<int, int>;
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generate(image);
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}
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Histogram::~Histogram()
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{
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delete R;
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delete G;
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delete B;
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delete L;
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}
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void Histogram::generate(QImage* image)
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{
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int width = image->width();
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int height = image->height();
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for (int x = 0; x < width; x++) {
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for (int y = 0; y < height; y++) {
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QRgb pixel = image->pixel(x,y);
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// Get color values
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int r = Histogram::R->value(qRed(pixel));
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int g = Histogram::G->value(qGreen(pixel));
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int b = Histogram::B->value(qBlue(pixel));
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int l = Histogram::L->value(qGray(pixel));
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// Insert color values
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Histogram::R->insert(qRed(pixel), r+1);
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Histogram::G->insert(qGreen(pixel), g+1);
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Histogram::B->insert(qBlue(pixel), b+1);
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Histogram::L->insert(qGray(pixel), l+1);
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}
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}
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}
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/** Returns the maximal value of the histogram in the given channel */
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int Histogram::maximumValue(Channel selectedChannel = RGB)
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{
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// Create and set max value
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int max = 0;
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// Iterate over values
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for(int i = 0; i < R->size(); i++)
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{
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if(R->value(i) > max)
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{
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max = R->value(i);
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}
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}
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for(int i = 0; i < G->size(); i++)
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{
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if(G->value(i) > max)
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{
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max = G->value(i);
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}
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}
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for(int i = 0; i < B->size(); i++)
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{
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if(B->value(i) > max)
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{
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max = B->value(i);
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}
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}
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for(int i = 0; i < L->size(); i++)
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{
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if(L->value(i) > max)
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{
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max = L->value(i);
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}
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}
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return max;
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}
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/** Returns a pointer to the given channel QHash<int, int> */
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QHash<int, int>* Histogram::get(Channel channel = LChannel)
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{
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if (channel==LChannel) return L;
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if (channel==RChannel) return R;
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if (channel==GChannel) return G;
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if (channel==BChannel) return B;
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return 0;
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}
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/**
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* Returns a 255 by 100 QImage containing a Histogram for the given channel.
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* The background is transparent (Alpha 0, RGB=255) */
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QImage Histogram::getImage(Channel channel = LChannel, QBrush pen = Qt::gray)
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{
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// Create blank QImage and fill it with transparent background:
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QImage histImage(255, 100, QImage::Format_ARGB32);
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histImage.fill(0);
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QPainter painter(&histImage);
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painter.setBrush(Qt::transparent);
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painter.setPen(Qt::transparent);
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painter.drawRect(0,0,255,100);
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// Calculate the aspect ratio using the maximal value of the color histograms
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int maximum = (channel == LChannel ? maximumValue(LChannel) : maximumValue(RGB));
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float ratio = 100.0/float(maximum);
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// Preparing the painter:
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painter.setBrush(pen);
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painter.setPen(pen.color());
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int h;
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// Draw histogram
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QHash<int, int>* hist = get(channel);
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QHash<int, int>::const_iterator cit = hist->begin();
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while (cit != hist->end())
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{
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h = 100 - floor(ratio*cit.value());
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painter.drawLine(cit.key(), h, cit.key(), 100);
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++cit;
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}
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return histImage;
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}
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