title: What does JET mean in the Image Processing in Python_Final.ipynb tutorial?
body: <p>I would like to ask a question regarding the
  <a href="https://colab.sandbox.google.com/github/xn2333/OpenCV/blob/master/Image_Processing_in_Python_Final.ipynb#scrollTo=XUMXfKr5gMl9" rel="nofollow noreferrer">Image Processing in Python_Final.ipynb tutorial</a>. In <strong>Step6: Finding Edges by Highpass Filtering in FFT</strong>, the third image is titled as <strong>Result in JET</strong>.
  What does JET stand for?</p>