Scale bar of data from clustering?

[gse]

I loaded my peak file (BED) and ChIP-seq aligned reads (BAM files) and discovered nice clusters that emerged. The clustering works wonderfully, but I cannot see a scale for each dataset. How can I add a scale bar to the heatmap?

For reference, Figure 4A of the SeqMINER paper shows the scale bar of each data set. This is exactly what I hope to do.

http://nar.oxfordjournals.org/content/39/6/e35/F4.large.jpg

Thank you for your time!

Graham