Hm, I am not entirely sure what you are asking. Individual object sizes can be measured by MeasureObjectAreaShape which will deposit the measurements into the output file. You can then export the sizes to an Excel file using the data tool ExportToExcel or you can show the sizes on one of your images using the ShowDataOnImage data tool. Note that the MeasureObjectAreaShape module records size measurements like area, major axis, minor axis, etc. It does not directly record diameter, which is the measurement that the IdentifyPrimAutomatic uses. IdentifyPrimAutomatic uses diameter because it is convenient to use the ShowPixelData option from the CellProfiler ImageTools menu (in a figure window, this option is available) to measure your cells in images by their width/diameter (whereas it is very tough to ‘eyeball’ cell area!) However, diameter only makes sense for a circular object, and objects are rarely circular, so diameter is not a measurement that is stored in the output by MeasureObjectAreaShape.
When you enter min/max sizes in the IdentifyPrimAutomatic module, it internally converts those diameter values to area values, based on a circle. In its display window after processing an image, it shows you the range of sizes of objects that are found, in diameter units (It shows the 5th and 95th percentile diameter values; again the diameter is calculated from the area of the objects, as if they were circular).
To show a histogram you could use the data tool Histogram. I’d recommend plotting the area measurements, then you could calculate sizes in your head.
Hopefully that explains everything you wanted to know about sizes in CellProfiler. But it’s all a little unclear why this is such a concern to see what the answers are - usually people determine if the settings are good by looking at the figure window of IdentifyPrimAutomatic and deciding whether the cells look properly identified, and in the bottom left corner seeing whether the cells are discarded by size properly (the red outlines are the cells discarded by size).
We typically want the settings to be consistent from image to image for scientific reasons, so I don’t think most users would want the min and max sizes to change from image to image, especially given that those parameters affect the cell identification itself, and not just whether the cells are thrown out of analysis or not. You are welcome to add the feature to the code yourself, if you like!