Projection system and automatic setting method thereof

A projection system, comprising:

• a processing device;
• and
• a first projector, coupled to the processing device, and the first projector comprising:
• a first projection unit, configured to project a first reference image onto a projection plane;
• and
• a first image capturing unit, configured to capture the first reference image on the projection plane to obtain a first captured image, wherein the first captured image comprises the first reference image and a background image,
• wherein the first projection unit projects a second reference image onto the projection plane through the processing device, and the first image capturing unit captures the second reference image on the projection plane through the processing device to obtain a second captured image, wherein the second captured image comprises the second reference image and the background image,
• wherein the processing device processes pixel values of a plurality of pixels of the first captured image and the second captured image subtracting from each other to obtain a pixels-subtracted image, the processing device analyzes the pixels-subtracted image to determine;
• a region having the pixel values greater than a threshold value in the pixels-subtracted image, wherein the region is defined as a valid identification region, and the valid identification region is associated with an area of the projection plane onto which the first reference image and the second reference image are projected;
• or
• a region having the pixel values less than the threshold value in a pixels-subtracted image, wherein the region is defined as a non-valid identification region, and the non-valid identification region is associated with the background image,
• the processing device is adapted to compare the first captured image and the second captured image to obtain a position of an image region having a pixel value change among the first captured image and the second captured image, and the processing device defining the position of the image region having the pixel values greater than the threshold value in the pixels-subtracted image.