Symphony.

Is there some extension that adds different image filters to JIT Image? I would like to do some black and white effects, possibly sepia as well.

BW effects are a terrible dream if it is cross browser. Best approach for bw with js is http://gianlucaguarini.github.io/jQuery.BlackAndWhite/. No sepia included.

Regarding JIT, it has no plugin architecture, AFAIK. So you would have to hack it to add new filters.

My customers want black and white images on their site, and I'm not fan of JavaScript solutions because thing has to work smoothly on mobile and in my country people don't have super duper expensive phones which run everything smooth.

I was hoping there was existing solution. I guess it's progressive enhancement with CSS than.

To not over complicate things. If you want bw pics make them bw. Ansel Adams would turn in his grave if it wasn't genuine.

Purely css and cross platform you won't win. Tough the php GD library got a filter function. But as Michael said you got to hack it.

Well, my customers are very lazy, and they don't want to edit photos at all. Just upload them and let the magic do its work :D

Which is reasonable to me. Why spend more time editing images when it can be automated.

some css and a little javascript for the lazy people ;-)

I guess you could hack into JIT (e. g. GD) for this. But I wouldn’t know where to start …