Creating 3-D Red/Blue Anaglyphs from Photographs
The greater the amount of parallax, the greater or more pronounced the ghosting problem. Ghosting in anaglyphs is a common problem when some light is not completely filtered and is visible in the wrong channel/eye. Ghosting is similar to what printers call hue error in printing. The ghost appears as a grey or dark shadow that is part of the parallax or misregister. RGB LCD monitors with their greater color gamut, have more pure colors and tend exhibit less ghosting than a CMYK print. A printer producing a CMYK anaglyph should be aware of the ghosting issue and carefully proof the anaglyph. Some ghosting is inevitable, and the ghosting may not be that noticeable or objectionable. When creating the left and right photographs, the greater the distance between the left and right images, the greater the parallax and the potential for objectionable ghosts. Anaglyph software allows the adjustment of the position of the left/right images and ghosting can be somewhat reduced by decreasing the amount of parallax.
The circled areas in the parallax of this anaglyph will show a ghost in a CMYK print that is not visible on an LCD monitor
Another phenomenon that detracts from the quality of an anaglyph is a difference in the brightness/luminance of the left and right image. This creates a phenomenon referred to as retinal rivalry. Retinal rivalry may cause parts of the image to shimmer and cause the viewer more discomfort when viewing the anaglyph. Retinal rivalry is common when using a single lens camera as the brightness of the left and right image can vary, or when attempting to do color corrections with the left and right images. Right and left images adjusted in Photoshop should maintain their same brightness/luminosity. Color correction to increase the visible red in the anaglyph often creates retinal rivalry.