This method is probably easier to apply than method 1, but when method 1 works the results may be superior. This method uses a weighted average of all frames, the bias applied to each pixel when summing decreases as it gets lighter. The method also lightens darker shades thus filling shadows, and also brightens/darkens the finished result before reverting to the normal 0 to 255 colour values.
The method uses a function on the Stack menu called 'Enhanced Average to Out' but I think it is easier to use a macro that calls it, here is a good example:-
As usual download this and place it in the same folder as CombineZM.exe, then load it into CZM using Macro->Load Macro Set, and a new item will appear on the Macro Menu called 'Dynamic Range Enhancement'. To use this load your stack, align it if necessary, then click on Macro->Dynamic Range Enhancement. Now an initial result will be generated and a Macro Parameters dialog will appear on top of it, adjust the parameters and Click OK to repeat the process, when satisfied with the result click on Cancel/End Macro, a new frame will be placed at the top of the stack which is a copy of the Out result.
Here is an example provided by David Lozoya, the original pictures were much larger but I have reduced them in size for use on this web page.
On launching the macro, and allowing it to run once, the screen looks like this:-
I have moved the dialog to one side. The result is better than the originals, though rather similar to the middle one. Notice the dark shadows that need filling in, I will increase the Dark Gain parameter to 550 and press OK to see what the result looks like.
That's about the best that can be done with this difficult scene. Increasing the Dark Gain too much causes posterization, the range of colours at mid brightness is squeezed so the picture looks flatter. Here for example this parameter has been set to 800.
The second parameter Light Attenuation is set to maximum at the moment, here is what happens at 0, the view through the window looks foggy.
The last parameter just adjusts the overall brightness of the image, use values in the range 0 to 1000 for all parameters except this one values below 1000 make the picture darker, greater than 1000 lighter.
A further sample using my own microscope pictures.