[FFmpeg-devel] [PATCH] avfilter: add midequalizer filter

[Calvin Walton]

Hi, just a quick note below...

On Thu, 2017-02-02 at 14:40 +0100, Paul B Mahol wrote:
> 
> +++ b/doc/filters.texi
> @@ -9643,6 +9643,17 @@ Macroblock size. Default @code{16}.
>  Search parameter. Default @code{7}.
>  @end table
>  
> + at section midequalizer
> +
> +Apply Midway Image Equalization effect using two video streams.
> +
> +This filter accepts the following option:
> +
> + at table @option
> + at item planes
> +Set which planes to process. Default is @code{15}, which is all
> available planes.
> + at end table
> 

Speaking as a user, it would be great if you can include some
information in the docs about what this filter does, or why someone
would want to use it. Something as simple as:

"Midway Image Equalization adjusts a pair of images to have the same
histogram, while maintaining their dynamics as much as possible. It's
useful for e.g. matching exposures from a pair of stereo cameras"

would help here.

Some help on how to actually use it (maybe with an example) would be
great too. For example, if the filter works by having a reference input
and an input which gets modified, it would also be good to say which
input is which. Something along the lines of:

"This input has two inputs and two outputs. The first input is used as
a reference, it is passed through unchanged. The second input has its
contrast adjusted to match that of the first input and the result is
returned on the second output."

but of course adjusted to match what the code actually does!

I don't have any comments on the code itself.

Calvin.