1. An image processing device comprising: a phase calculation unit configured to calculate a phase of pixels of a 3D image projected onto a light shielding unit that limits a region seen by a left eye and a region seen by a right eye of the 3D image displayed on a display unit; and a blend processing unit configured to combine an image for the left eye with an image for the right eye for each pixel based on the phase calculated by the phase calculation unit, the image for the left eye and the image for the right eye being included in the 3D image.