fill transparent images with background color

![screen shot 2014-03-03 at 17 01 02](https://f.cloud.github.com/assets/128982/2309539/40b7c602-a2d5-11e3-8ffe-e5a7882df26f.png)
![screen shot 2014-03-03 at 17 00 52](https://f.cloud.github.com/assets/128982/2309540/434af678-a2d5-11e3-9acf-336a53aa20d0.png)