Error level analysis

Error level analysis is a way to detect if a picture has been changed using photo editing software. Imagine you have a drawing of a cat that you colored in with your crayons. Each color you used is like a different layer in your picture. Now, let's say you want to change the color of the cat's nose from pink to green, but you don't want anyone to know you made this change. So, you use a computer program to change the color of just the nose layer to green.

Error level analysis can help us spot this change. Think of each layer of the picture as a fancy cake. When you add frosting to the cake, it creates a smooth surface. But, if you add another layer of frosting to only one part of the cake, that area will have a different texture compared to the other parts. This is what happens when you make a change to a layer in a picture.

When a picture is saved, the software gives each layer or section of the image a certain level of compression. Compression is like squeezing all the air out of a balloon. The more you squeeze, the flatter it becomes. When a picture is changed, the compression level of the edited area will be different than the rest of the picture. This difference in compression levels can be detected by error level analysis.

By comparing the different levels of compression in each layer of the image, we can see if any part of the picture has been changed. Error level analysis helps us tell if someone has tried to trick us by making changes to a picture.