I have been experimenting with the HTC One camera and tried the filters or effects you can switch on before you take a photo. Of course the editing options after you take a photo are numerous including removing people out of your photo who appeared .
Rather than describe each effect in detail just look at the same item with different effects applied. Some really interesting differences.
The above distorts the tea cake.
The above creates a darker edge. Ideal for focusing central subject.
The above is rather unusual.
The last one looks a bit creepy but all in all some amazing results.