title: How to improve lines quality of a heat map
body: <p>I have plotted the matrix of numbers of this file</p>
  
  <p><a href="https://www.dropbox.com/s/xil30t8lgvca00g/pher-of-1365.txt?dl=0" rel="nofollow noreferrer">pher-of-1365.txt</a></p>
  
  <p>with this code</p>
  
  <pre><code>set encoding iso_8859_1
  set term postscript eps enhanced color size 4.7in,4in
  set xlabel "longitude"
  set ylabel "latitude"
  set output "test0.eps"
  set size square 
  set title "Pheromones" font "Helvetica, 16"
  set autoscale fix
  set key
  set yrange [:] reverse
  set view map
  splot 'pher-of-1365.txt' matrix with image
  </code></pre>
  
  <p>Which produces this plot:</p>
  
  <p><a href="https://i.stack.imgur.com/xJmUQ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/xJmUQ.png" alt="enter image description here"></a></p>
  
  <p>The quality is not bad but the lines look blurred.</p>
  
  <p>Is there a way to improve the clarity of the lines in the image?</p>
  
  <p>Regards</p>