In a color correction method, a reference area is selected in a document page, which is rendered to produce image data. The reference area can be a company logo, a letter or character in a line of text, or other graphic object. The reference area need not be a set calibration chart. The image data is used by a projector to display the document page on a screen. Ambient light may cause colors in the displayed document page to be noticeably different from the intended colors specified in the document page. A camera takes a picture of the displayed document page, and a target area is identified in the camera image based on a characteristic of the reference area that was previously selected. Corrected image data is generated based on a color difference between the reference area and the target area. The projector uses the corrected image data to display the document page, this time with colors that are closer to or the same as the intended colors. The cycle may be repeated on the next document page, in which case the reference and target areas may differ from those of the previous cycle.