Topic: semitransparent mask over pictures

Hello guys,

I want to apply shading effect to images, but I'd like to have a semi-transparent gradient shading, with maximum alpha at sides of non-active images and 0% alpha at active image. So, non-active images kind of fading out
Any ideas if this effect can be implemented and how much would this cost, also how long it may take.

Here is an example of this effect:

Many thanks in advance,