How to apply image effects to pictures on Raspberry Pi

Like a common pocket camera which has a built-in function to add various effects on captured photos, Raspberry Pi camera board (“raspi cam”) can actually do the same. With the help of raspistill camera control options, we can add the image effects function like we have in a pocket camera. There are three comman-line applications which can be utilized for taking videos or pictures with raspi cam, and one of them is the raspistill application.