Hi Darren,

Just so we are using the same terms the setting of ** really refers to the color scale of the color bar (color pbar). The intensity slider is in the green region next to the color bar. The slider controls what can be seen. If it can be seen, then the color scale determines its color.

What it sounds like is happening to you is that when you change the color scale to 9 from ** you lose some clusters. If you notice, the setting of 9 has one section with a color of "none." Probably a few clusters are being eliminated because their values are in the scaled range of "none." The scaling is determined by the autoscale function button, or a range that you can set manually if you unclick the autoscale button.

The clusters are still in the data, they just have different values in the two datasets as a result of your different 3dmerge commands. The -1clust data has the original data values. The -1clust_order command replaces the original data values with integers that signifiy the size order of the cluster. Each voxel that remains gets a reassigned and identical value per cluster in the -1clust_order. The same cluster formation criteria apply to both command versions.

-jim