Middle gray

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50% lightness in Lab color space

In photography, painting, and other visual arts, middle gray or middle grey is a tone that is perceptually about halfway between black and white on a lightness scale;[1] in photography, it is typically defined as 18% reflectance in visible light.[2]

Middle gray is the universal measurement standard in photographic cameras. To calibrate light meters, whether in a camera or hand held, the 18% gray card was conceived. It is assumed that the measurement taken by a meter gives the exposure for a shot so that some of the light reflected by the object measured is equivalent to middle gray.[3] However, many note that modern cameras generally treat 12-13% gray as "middle gray".

In the sRGB color space, middle gray is equivalent to 46.6% brightness.[4] In 24-bit color, this is rounded to RGB value (119,119,119) or #777777.[5]

History[edit]

In the Zone System of Ansel Adams, middle gray is known as "Zone V" in the scale of 11 zones from Zone 0 (black) to Zone X (white).[6]

As early as 1903, middle gray was defined as the geometric mean intensity between a white and a black intensity that are in a ratio of 60:1.[7] That is equivalent to 12.9% of the white intensity.

References[edit]

  1. ^ Stephen Quiller (1999). Painter's Guide to Color: Includes the New Quiller Color Wheel. Watson-Guptill. ISBN 0-8230-3913-7. 
  2. ^ Blain Brown (2002). Cinematography: Theory and Practice : Imagemaking for Cinematographers, Directors, and Videographers. Focal Press. ISBN 0-240-80500-3. 
  3. ^ Steven Barclay (1999). The Motion Picture Image: From Film to Digital. Focal Press. ISBN 0-240-80390-6. 
  4. ^ Geffert, Scott (2008). Adopting ISO Standards for Museum Imaging (Technical report). imagingetc.com, Inc. 
  5. ^ http://www.brucelindbloom.com/index.html?ColorCalculator.html
  6. ^ Jonathan Spaulding (1998). Ansel Adams and the American Landscape: A Biography. University of California Press. ISBN 0-520-21663-6. 
  7. ^ Daniel Coit Gilman, Harry Thurston Peck, and Frank Moore Colby (1903). The New International Encyclopædia. Dodd, Mead and Company.