Ziad and Hauke:
Thanks immensely for the clues on the Min-to-max option, and on the grayscale's context menu -- essential info, and sorry for the "RTFM moment".

That said, I continue to think that the 2%-98% option is broken. I am assuming that the intent here is to map the 2-percentile voxel's intensity to black (or zero) and the 98 percentile voxel's intensity to white (or 255). (Or corresponding position on colorscale).

Examples:

1. Voxels outside that range clip to black and white respectively... and that does happen if for example you have mostly 0, with a few thousand 128's and then a small number of 255's. The 255's appear on screen at same brightness as the 128's.

And the graymap plot corroborates all this so far.

2. But if you have mostly black and just a small number of 255's (presumably less than 2%) then the graymap plot arbitrarily adjusts to a silly configuration: Intensity 0 --> gray-50, intensity 0.5 --> gray-255.

Regardless of whether this is sensible, the few intensity 255 pixels should still appear on screen "clipped" to a gray-255... but they are in fact invisible.

I should note there are some mystery almost-vertical red lines on the graymap plot... not sure what they are supposed to indicate. I thought perhaps they indicated that voxels outside the red lines were ignored completely. This might explain example 2's invisible 255's, but it does not explain why the 255's are visible in example 1.

Anyhow, for the most part we're thoroughy relieved to discover the min-to-max option... but inasmuch as the 2%-98% is the default, it would be nice to know when it's going to surprise us

Graham