With the Trackplan Resource App you can edit and draw over an image when on a job.
When you open the Job Details of any job in the Jobs List you will see the "Photos Sent to App" section. This section will display any images that have been attached to the job:
Clicking on this image will display a pop-up window. On this pop-up there will also be an Edit button:
Selecting the Edit button will allow you to draw over the image if you wish. The "trash can" icon will delete any edits created, and the "floppy disk" icon will save any edits made:
If edits have been made and saved to this image, the edited image will now appear in the "Photos Taken From App" section, and the original will remain untouched, as seen below: