Fixing Redeye - Introduction

Modern cameras do a "pre-flash" which causes the pupil to constrict a little before the actual picture, which is reducing the amount of "redeye" pictures taken.  But still they happen.  The reason is that the light is low, a picture is taken with flash, but before the pupil can react, the photo is done.  The red color comes from the red blood vessels in the back of the retina. 

You can have delightful family photos, but they have that pronounced "redeye" effect.  Fortunately, this is simple to fix with Paint.NET.