title: Is this Fourier Analysis of Luminance Signals Correct? (Android)
body: <p>I'm writing an Android app that measures the luminance of camera frames over a period of time and calculates a heart beat using Fourier Analysis to find the wave's frequency. The problem is that my spectral analysis looks like this:</p>
  
  <p><a href="https://i.stack.imgur.com/NEovj.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/NEovj.png" alt="Spectral analysis (y-axis is magnitude, x-axis is index)"></a></p>
  
  <p>which is pretty much the inverse of what a spectral analysis should look like (like a normal distribution). Can I accurately assess this to find the index of the maximum magnitude, or does this spectrum reveal that my data is too noisy?</p>
  
  <p>EDIT:
  Here's what my camera data looks like (I'm performing FFT on this):
  <a href="https://i.stack.imgur.com/uJYDU.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/uJYDU.png" alt="Luminance of Current Frame vs. Time"></a></p>