How to post pictures to instagram using API

I am building a php application which needs to post the user uploaded picture directly to Instagram, but after a quick search i found that there is no such function in the API 🙁 and it feels weird… because they should provide one. I am not sure if there is any other way (except the apps for android and iOS) to upload picture using php. Kindly give me any sort of idea if there is any possibility.