diff --git a/spectrogramplot.cpp b/spectrogramplot.cpp
index 437b4f6..7ee1dd2 100644
--- a/spectrogramplot.cpp
+++ b/spectrogramplot.cpp
@@ -97,11 +97,11 @@ QPixmap* SpectrogramPlot::getPixmapTile(off_t tile)
     float *fftTile = getFFTTile(tile);
     obj = new QPixmap(linesPerTile(), fftSize);
     QImage image(linesPerTile(), fftSize, QImage::Format_RGB32);
+    float powerRange = -1.0f / std::abs(int(powerMin - powerMax));
     for (int x = 0; x < linesPerTile(); x++) {
         float *line = &fftTile[x * fftSize];
         for (int y = 0; y < fftSize; y++) {
-            float powerRange = std::abs(int(powerMin - powerMax));
-            float normPower = (line[y] - powerMax) * -1.0f / powerRange;
+            float normPower = (line[y] - powerMax) * powerRange;
             normPower = clamp(normPower, 0.0f, 1.0f);
 
             image.setPixel(x, fftSize - y - 1, colormap[(uint8_t)(normPower * (256 - 1))]);