implemented contrast slider

adjustpicturedialog.cpp

@@ -4,23 +4,24 @@
 #include <opencv2/imgcodecs.hpp>
 #include <opencv2/imgproc.hpp>
 #include <string>
-#include <iostream>
 #include <opencv2/core/mat.hpp>
+#include <QColorTransform>
 #include <QFileDialog>
 #include <QMessageBox>
 #include <zbar.h>
 
 AdjustPictureDialog::AdjustPictureDialog(QWidget *parent, std::string imagePath)
     : QDialog(parent)
-    , ui(new Ui::AdjustPictureDialog){
+    , ui(new Ui::AdjustPictureDialog)
+    , pixmap(QString::fromStdString(imagePath))
+    , img(pixmap.toImage()){
     ui->setupUi(this);
 
+    computeContrastLookupTable();
+
     scene = new QGraphicsScene(this);
 
     ui->graphicsView->setScene(scene);
-    QGraphicsPixmapItem p;
-    QString path = QString::fromStdString(imagePath);
-    QPixmap pixmap = QPixmap(path);
     scene->addPixmap(pixmap);
 }
 
@@ -66,12 +67,39 @@ std::string AdjustPictureDialog::decode() {
         result = symbol->get_data();
     }
 
-
-
     return result;
 }
 
-void AdjustPictureDialog::on_contrastSlider_sliderMoved(int position) {
+void AdjustPictureDialog::computeContrastLookupTable() {
 
+    for (int contrastValue = 0; contrastValue < 100; ++contrastValue) {
+        double contrast = contrastValue / 50.0;
+        for (int i = 0; i < 256; ++i) {
+            unsigned short correctedValue = std::clamp(static_cast<int>(128 + contrast * (i - 128)), 0, 255);
+            contrastLUT[contrastValue].push_back(correctedValue);
+        }
+    }
+}
+
+void AdjustPictureDialog::on_contrastSlider_sliderMoved(int position) {
+    QImage image = img.copy();
+
+    uint32_t* pixels = reinterpret_cast<uint32_t*>(image.bits());
+    int width = image.width();
+    int height = image.height();
+
+    for (int y = 0; y < height; ++y) {
+        for (int x = 0; x < width; ++x) {
+            QRgb rgb = pixels[y * width + x];
+            pixels[y * width + x] = qRgba(
+                contrastLUT[position][qRed(rgb)],
+                contrastLUT[position][qGreen(rgb)],
+                contrastLUT[position][qBlue(rgb)],
+                qAlpha(rgb));
+        }
+    }
+
+    scene->clear();
+    scene->addPixmap(QPixmap::fromImage(image));
 }