A trial procedure to render H-Alpha picture (whole Sun ) more homogeneous ... if you find some easy ameliorations please tell me about !

The process goes like this :
1. make a copy of the sharpened image ... this will be the mask
2. apply a very high value Gaussian blur (example 100)
3. transform to negative
4. fill the white space with black paint
5. multiply the original image by the mask applying a moderation dividing factor

The process which is not software dependant is illustrated below with PSP ...


ORIGINAL sharpened H-Alpha IMAGE : Top and bottom are darker !
From left to right : Gauss 100*** / negative / outside black painted         *** This parameter is important and the best value will be found by trials.
Multiply operation using a moderation (dividing) factor of 128 ... less than 128 gives a brighter image, more than 128 a darker one
The improvement resulting of the EQUAL processing speaks for itself !

Improving a mosaic by the same technique ...