How do I search for an image using another image as the criteria?
There are a few ways. If you are looking for an exact match you can use a program that creates unique hashes based on the contents of the file that will determine with certainty that it is identical. There are many free programs available to do this. Wikipedia lists open source/free duplicate file finders:
The second method involves using a program that is able to compare two photos possibly of different sizes and estimate whether they are of of the same image. This is called a “reverse image search”. For Windows as of the writing of this article there is a free package called Visipics which can do a reverse image search on your hard drive. Visipics is also reported to work under Linux utilitizing the wine virtualization software. This package can be found here: