"Pixelation" can be a result of lots of different things, such as the discreteness of the actual data, the interpolation method for storage and display, but this might be the result of how the color is mapped to the image. I can get images very similar to this if I change the color scale used to the 10-pane version by clicking below the colorbar in the overlay panel and choosing 10. If I switch back to the "**" choice, I get a more smoothly varying image by using a continuous colorscale. Also see the effect of the display resampling interpolation types in the Define Datamode menu for the "OLay Resam mode" and "Stat Resam mode" choices.