title: Customizing color range in image.plot in R
body: <p>Is there a way to plot values above the zlim cutoff in the image.plot() function?  Here's an example:</p>
  
  <pre><code>library('gplots')
  library('fields')
  library('RColorBrewer')
  
  rf &lt;- colorRampPalette(rev(brewer.pal(11,'Spectral')))   # make colors
  r &lt;- rf(64)
  
  z &lt;- matrix(data = 0, nrow = 3, ncol = 3)
  z[1,1] &lt;- .15
  z[2, ] &lt;- .10
  z[3, ] &lt;- .05
  
  image.plot(z,
             col = r,
             zlim = c(0, .10))
  </code></pre>
  
  <p>This code produce this image:</p>
  
  <p><a href="https://i.stack.imgur.com/GyX5y.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/GyX5y.png" alt="enter image description here"></a></p>
  
  <p>I'd like it if the lower left corner (.15) was colored red (like the .10).  But I couldn't find a way to do that with image.plot() function. </p>
  
  <p>I should mention that need the legend.  Also, the real data is much larger. Any ideas?</p>