title: "pixel dimension information" when plotting with image in gnuplot
body: <p>Using gnuplot v5 patch 6 on windows 10 (wxt terminal)</p>
  
  <p>I have a data file of 2D vectors arranged in six columns (x, y, v_x, v_y, v_mag, rho) that I'm trying to plot as a heatmap of v_mag against x and y. The plot generates fine, but it's always coming up with </p>
  
  <pre><code>"No dimension information for 80000 pixels total. Try 200 x 400" 
  </code></pre>
  
  <p>But I have no idea where to specify this in the terminal.</p>
  
  <p>I realise that I can use pm3d map for this, but this doesn't work without setting dgrid3d and that causes problems with plotting dots on top of the heatmap which I'm also doing. I also don't want to generate a matrix file just for the image plot since I need the vector data for analysis later.</p>
  
  <p>In terms of an example, the plot will generate if I literally just write:</p>
  
  <pre><code>plot 'vectors.dat' using 1:2:5 with image, 'dots.dat' with dots 
  </code></pre>
  
  <p>EDIT: added 'set pm3d' to example code</p>
  
  <p>EDIT: example is now minimal code to produce desired plot</p>
  
  <p>EDIT: example data file can be found <a href="https://drive.google.com/open?id=0B3Hs48aL9CECTXZlZE8zVVFuOEE" rel="nofollow noreferrer">here</a></p>
  
  <p>Any help would be appreciated.</p>