Projection system, interactive projection method and projector

An interactive projection method, comprising:

• projecting an interactive image onto a projection target through a projection unit;
• photographing at least one physical writing content circled by an operation pen on the projection target through a photographing unit to obtain an image;
• and
• wherein the interactive image projected by the projection unit comprises a writing image, and the writing image comprises the at least one physical writing content.

A projector, comprising:

• at least one processing unit;
• a projection unit, electrically coupled to the at least one processing unit and configured to project an interactive image onto a projection target;
• and
• a photographing unit, electrically coupled to the at least one processing unit and configured to photograph at least one physical writing content circled by an operation pen on the projection target to obtain an image,
• wherein the interactive image projected by the projection unit comprises a writing image, and the writing image comprises the at least one physical writing content.