Adding an Image field in webform module
To add an image field to a webform:


To go the webform tab where you manage the fields.
Add a new field of type file: 
On the new field configuration page it's a good idea to set an Upload directory for your images. This means all the images upload from this field will sit in a particular folder in your files directly and help prevent too many files from sitting in one folder. You can also choose what types of files you want to allow users to upload. For an image field I would suggest only gif, jpg, and png. 
Set any other settings such a label or display settings as required.
Finally save the component. 
Now when you visit the frontend of your webform you should see your new field: