What are the most commonly used enzymes in colorimetric detection for western blot?

The most commonly used enzymes in colorimetric detection for western blot are horseradish peroxidase (HRP) and alkaline phosphatase (AP). The membrane is probed with a labeled secondary antibody and the conjugated enzyme generates a signal corresponding to the presence of the target protein, which is captured on a film. This film is typically formed in a darkroom to visualize the signal.