What is “perspective correction”?

This term usually* refers to rendering vertical lines in the scene as vertical in a photograph.

*The term can also refer to rendering horizontal lines as horizontal, but this is less common outside of product photography.

There are two ways to “correct” perspective:

1. Point the camera “square on” at the subject before taking the picture

2. After the light from the scene hits the recording surface, reshape things in the photo so that it looks like the camera had been pointed somewhere other than where it actually had been pointed.

(#2 is called “post-exposure perspective correction,” or PEPC)

What does TTG allow?

• Only the #1 method can be used to make TTG photos.

• Doing #2, by any method, always disqualifies the result from TTG.