diff --git a/UIImage+Spectrogram/ImageUtils.swift b/UIImage+Spectrogram/ImageUtils.swift
index 85741e3..db3d1f5 100644
--- a/UIImage+Spectrogram/ImageUtils.swift
+++ b/UIImage+Spectrogram/ImageUtils.swift
@@ -43,7 +43,7 @@ public class ImageUtils {
         let timeWidth = magnitudes.count
         let frequencyHeight = magnitudes.first!.count
         
-        let pixels = magnitudes.map{ $0.map{ RGBA<Float>(gray: 1-$0) } }
+        let pixels = magnitudes.map{ $0.map{ ImageUtils.colorForMagnitude(1.0 - $0) } }
         
         let flattenedPixels = pixels.flatMap{ $0 }
         
@@ -87,4 +87,11 @@ public class ImageUtils {
     public static func mixColor(magnitude: Float) -> UIColor {
         return UIColor(hue: 0.75, saturation: CGFloat(magnitude), brightness: 1.0, alpha: 1.0)
     }
+
+    private static func colorForMagnitude(_ mag: Float) -> RGBA<Float> {
+        let color = UIColor(hue: CGFloat(mag), saturation: 1.0, brightness: 1.0, alpha: 1.0)
+        var r: CGFloat = 0, g: CGFloat = 0, b: CGFloat = 0, a: CGFloat = 0
+        color.getRed(&r, green: &g, blue: &b, alpha: &a)
+        return RGBA<Float>(red: Float(r), green: Float(g), blue: Float(b), alpha: Float(a))
+    }
 }