NIH Image

Displays a plot showing the distribution of gray values within the selection. The plot shows, for each of the possible 256 gray values, the number of pixels in the selection that have that gray value. When the cursor is over the Histogram window, X (the gray value) and Y (the number of pixel with that gray value) are displayed dynamically in the Info window. Note that the Histogram command works with non-rectangular selections. The Copy command, when the histogram window is the active window, copies both the histogram plot (as a PICT) and the histogram data values (as a single column of text) to the clipboard. Histogram data values can also be saved to a text file using the Export command.

Image SXM

If the option key is pressed then, in addition to displaying the histogram window, the histogram data is copied into a plot window. The plot can be customised using the Profile Plot Options by double-clicking in the plot window.