Hey there, sorry to say that I haven’t experimented any further with retinal vessel images
But concerning the usage of RemoveOutliers, notice that the pixels that you want replaced have to have the value “NaN”. Try the following snippet, which sets a rectangular ROI to the value NaN and then runs the plugin. Notice how the values on the border of each of the four sides of the ROI are diffused towards the center.
newImage("Untitled", "32-bit ramp", 512, 512, 1);
run("Duplicate...", " ");
makeRectangle(160, 185, 103, 65);
run("Remove Outliers", "block_radius_x=40 block_radius_y=40 standard_deviations=3");
To run the macro, do File > New > Script… paste the lines in there, change the language to IJ1 Macro and run.
Good luck, David