Open this dialog by clicking 
on the Interactive Repair Toolbar
Pixel Repair Preferences
The Pixel Repair Preferences dialog is used to configure the Interactive Repair command. Here you can change the size of the neighborhood used to generate a new pixel value and also tell it whether you are zapping hot pixels or cold defects.
Open this dialog by clicking on the Interactive Repair Toolbar
The sample region affects the size of the artifact you can repair with the tool. For small artifacts like isolated pixels, choose a small sample region. If you try to work away at the edges of a large defect it is best to use a larger sample region to "pull in" good comparison pixels from far away from the pixel of interest.