Surface plots in a log scale

Hi there

I am generating a 2D surface plot of the velocity magnitude. I have small regions with very high velocity magnitude compared with the remainder of the plot. This means I have small regions of red and the remainder of the plot is blue so the velocity gradient within the blue portion of the plot cannot be visualised very clearly. I tried plotting log(spf.U) and this helped with the visualisation but then the colour legend was not easy to interpret. I would like to have the colour legend labelled with the original velocity values, not the log values. Is this possible?

Thanks