Color Correction of Smartphone Photos with Prior Knowledge

Human visual system has the property of perceiving the object color to remain constant regardless of the prevailing illumination. However, digital cameras usually lack this capability, and the captured images are digitally corrected to discount the color of the scene light based on the estimated illuminant. Illumination estimation might be erroneous in some artificial or chromatic lighting conditions. A method was proposed to correct digital photos captured with a smartphone camera using the smartphone owner’s face as the reference. Taking the advantage of the latest smartphones with two build-in cameras, we could use the front camera to capture the smartphone owner’s face and compare with the saved reference face image in order to estimate the scene illuminant. After that, we could properly adjust the capture setting for the main camera in order to take a decent target image; or we could automatically correct the target image based on the estimated illumination by comparing two face images. The method was implemented on the iOS mobile platform. Experimental result shows that the adjusted images using the proposed method are generally more favorable than the pictures taken directly by the default camera application.