US Patent 11838695 Projection apparatus and keystone correction method

A projection apparatus and a keystone correction method thereof are provided. The projection apparatus includes a display processing circuit including an image processing circuit, a first keystone correction circuit, a rotation circuit, a second keystone correction circuit, and a video output circuit. The first keystone correction circuit performs first keystone correction processing on a processed image frame based on horizontal scaling processing to obtain a first corrected image frame. The rotation circuit performs rotation processing on the first corrected image frame to write a rotated image frame into a memory. The second keystone correction circuit reads the rotated image frame from the memory and performs second keystone correction processing on the rotated image frame based on the horizontal scaling processing to obtain a second corrected image frame. The video output circuit transmits the second corrected image frame to a projection module through a data transmission interface.