diff --git a/mainwindow.cpp b/mainwindow.cpp
index aae8c33..cb70dc0 100644
--- a/mainwindow.cpp
+++ b/mainwindow.cpp
@@ -14,5 +14,5 @@ MainWindow::MainWindow()
 
     connect(dock, SIGNAL(fftSizeChanged(int)), &spectrogram, SLOT(setFFTSize(int)));
     connect(dock->powerMaxSlider, SIGNAL(valueChanged(int)), &spectrogram, SLOT(setPowerMax(int)));
-    connect(dock->powerRangeSlider, SIGNAL(valueChanged(int)), &spectrogram, SLOT(setPowerRange(int)));
+    connect(dock->powerMinSlider, SIGNAL(valueChanged(int)), &spectrogram, SLOT(setPowerMin(int)));
 }
\ No newline at end of file
diff --git a/spectrogram.cpp b/spectrogram.cpp
index 82a027e..35b84a2 100644
--- a/spectrogram.cpp
+++ b/spectrogram.cpp
@@ -10,7 +10,7 @@ Spectrogram::Spectrogram()
 {
 	inputSource = new InputSource("/home/mike/Downloads/hubsan-chopped.cfile", 1024);
 	powerMax = 0.0f;
-	powerRange = 40.0f;
+	powerMin = -50.0f;
 	resize(inputSource->GetWidth(), inputSource->GetHeight());
 }
 
@@ -95,6 +95,7 @@ void Spectrogram::paintEvent(QPaintEvent *event)
 		QImage image(width, height, QImage::Format_RGB32);
 		for (int y = 0; y < height; y++) {
 			for (int x = 0; x < width; x++) {
+				float powerRange = std::abs(powerMin - powerMax);
 				float normPower = (data[y*width + x] - powerMax) * -1.0f / powerRange;
 				normPower = clamp(normPower, 0.0f, 1.0f);
 
@@ -127,8 +128,8 @@ void Spectrogram::setPowerMax(int power)
 	update();
 }
 
-void Spectrogram::setPowerRange(int power)
+void Spectrogram::setPowerMin(int power)
 {
-	powerRange = power;
+	powerMin = power;
 	update();
 }
\ No newline at end of file
diff --git a/spectrogram.h b/spectrogram.h
index d216dcd..3d86f7f 100644
--- a/spectrogram.h
+++ b/spectrogram.h
@@ -13,7 +13,7 @@ public:
 public slots:
 	void setFFTSize(int size);
 	void setPowerMax(int power);
-	void setPowerRange(int power);
+	void setPowerMin(int power);
 
 protected:
 	void paintEvent(QPaintEvent *event);
@@ -23,5 +23,5 @@ private:
 	InputSource *inputSource;
 
 	float powerMax;
-	float powerRange;
+	float powerMin;
 };
\ No newline at end of file
diff --git a/spectrogramcontrols.cpp b/spectrogramcontrols.cpp
index d55b316..2b7595b 100644
--- a/spectrogramcontrols.cpp
+++ b/spectrogramcontrols.cpp
@@ -13,14 +13,14 @@ SpectrogramControls::SpectrogramControls(const QString & title, QWidget * parent
 	layout->addRow(new QLabel(tr("FFT size:")), fftSizeSlider);
 
 	powerMaxSlider = new QSlider(Qt::Horizontal, widget);
-	powerMaxSlider->setRange(-60, 20);
+	powerMaxSlider->setRange(-100, 20);
 	powerMaxSlider->setValue(0);
 	layout->addRow(new QLabel(tr("Power max:")), powerMaxSlider);
 
-	powerRangeSlider = new QSlider(Qt::Horizontal, widget);
-	powerRangeSlider->setRange(0, 80);
-	powerRangeSlider->setValue(40);
-	layout->addRow(new QLabel(tr("Power range:")), powerRangeSlider);
+	powerMinSlider = new QSlider(Qt::Horizontal, widget);
+	powerMinSlider->setRange(-100, 20);
+	powerMinSlider->setValue(40);
+	layout->addRow(new QLabel(tr("Power min:")), powerMinSlider);
 
 	widget->setLayout(layout);
 	setWidget(widget);
diff --git a/spectrogramcontrols.h b/spectrogramcontrols.h
index 707cabd..03b6007 100644
--- a/spectrogramcontrols.h
+++ b/spectrogramcontrols.h
@@ -22,5 +22,5 @@ private:
 	QSlider *fftSizeSlider;
 public:
 	QSlider *powerMaxSlider;
-	QSlider *powerRangeSlider;
+	QSlider *powerMinSlider;
 };
\ No newline at end of file