Various issues with Contrast Enhancement app
Today I tried using the Contrast Enhancement app (OTB 6.4) for a simple workflow: take a 16 bit Pléiades XS image and make a high-contrast 8-bit version. I encountered a few issues with the app:
Cannot uint8 as output type. It works fine with uint16 (same as input type in my case), but when I change it to uint8 the output is full white (255) everywhere. At first I thought the reason was that the 'Contrast limitation' parameter depends on the output type range, because decreasing it showed some darker areas, but decreasing it further did not help yield a good looking output.
'Minimum and maximum definition': These parameters are extremely unclear. What is their purpose? Why should a user ever need to change it? How does it relate to the output type range? How is it set when set to 'Automatic'?
Automatic min/max definition has a 'global' mode? Again, why is that useful to change? Plus, it looks like a lonely check box in GUI, very unclear.
Cannot start the app in GUI when switching to "Manual minimum and maximum computation". This is maybe a bug in Application Engine, but the "Execute" button is gray. Need to change the minimum field to 0.1 for example, then back to 0 for it to work.
Typos in documentation. There are a number of typos and errors in the documentation which should be fixed.
In my opinion, the purpose of this app is not to be a highly configurable front-end to adaptive histogram equalization, but a user friendly way to go from a raw satellite image product to a reasonably good looking 8-bit image. Or perhaps we need another app for this? Discussion is welcome on this point.
Steps to reproduce