Digital Color Management: Encoding Solutions, 2nd Edition

E

Viewing Flare

When an image is viewed, the observer ideally should see only the light from the image itself. But in most actual viewing conditions, the observer also will see flare light, i.e., stray light containing no image information. For example, when viewing a video image displayed on a monitor, the observer may see flare light reflected from the glass faceplate of that monitor. The light causing the flare might come from ordinary light sources in the viewing environment (overhead lamps, window light, etc.). It also might come from the video display itself—if, for example, a workstation user is wearing a white shirt that reflects monitor light back to the CRT faceplate.

In reflection-image viewing, flare occurs as light is reflected directly from the front surface of the medium, without passing through the colorants that make up the image. The amount of flare will vary, depending on the surface texture of the medium, viewing angle, and other factors. In projection-image viewing, viewing flare can be caused by stray projector light. Flare light also can come from projected light that first reflects from the projection screen to the various surfaces in the room and then reflects back to the screen. The amount of flare will depend on the type of screen, the characteristics of the room, the viewing angle, and other factors.

Effect of viewing flare on image grayscale

Viewing flare adds light, essentially uniformly, to the entire image being viewed. Flare light will significantly ...