脚本或命令，用于更改一组按顺序编号的文件的起始索引号

i have a set of files named img1.png , img2.png ,...img10.png,.. and so on. what i want to achieve is renaming these files so that the starting index is increased by 30 such that the files become img31.png, img32.png,.....img40.png,....and so on. Is this possible using the "rename" command? or is a script required? in either case how do i do this?i have a set of files named img1.png , img2.png