On Mac (OS X) I have a directory with many images named like this:

```
IMG_250x333_1.jpg
IMG_250x333_2.jpg
IMG_250x333_3.jpg
...

```

I need to rename all of them to:

```
IMG_1.jpg
IMG_2.jpg
IMG_3.jpg
...

```

I think using a UNIX command line with "mv" and a kind of regex would do the job, but I don't know how! Can someone please help?

Thanks!