I am using the Twitter4J API in Java to retrieve the profile image for a Twitter user whose logged in. The command is something like :
twitter.getProfileImag
Take a look at the example code. https://github.com/yusuke/twitter4j/blob/master/twitter4j-examples/src/main/java/twitter4j/examples/user/GetProfileImage.java
You can pass either ProfileImage.MINI, ProfileImage.NORMAL or ProfileImage.BIGGER