Power to the Purple!

A while ago I dyed some blue trousers red, hoping for purple.  The results were interesting but not purple.

I tried dying similar stonewashed jeans purple.  They came out dark purple.  Slightly disappointing.  I was hoping for the same two-tone look.  Either the base colour graduation was too subtle or the purple is too dark.  Either way it didn't work.  Just have the flat colour. 

I have another pair of blur stonewashed jeans.  What shall I do with them?