World Library  
Flag as Inappropriate
Email this Article

Color correction

Article Id: WHEBN0003296741
Reproduction Date:

Title: Color correction  
Author: World Heritage Encyclopedia
Language: English
Subject: Color grading, O Brother, Where Art Thou?, Compositing software, Waveform monitor, Da Vinci Systems
Collection: Cinematography, Photographic Techniques, Stage Lighting
Publisher: World Heritage Encyclopedia

Color correction

Color correction by using color gels, or filters, is a process used in stage lighting, photography, television, cinematography and other disciplines, the intention of which is to alter the overall color of the light; typically the light color is measured on a scale known as color temperature, as well as along a greenmagenta axis orthogonal to the color temperature axis.

Without color correction gels, a scene may have a mix of various colors. Applying color correction gels in front of light sources can alter the color of the various light sources to match. Mixed lighting can produce an undesirable aesthetic when displayed on a television or in a theatre.

Conversely, gels may also be used to make a scene appear more natural by simulating the mix of color temperatures that occur naturally. This application is useful especially where motivated lighting (lending the impression that it is diegetic) is the goal. Color gels may also be used to tint lights for artistic effect.


  • Correlated color temperature 1
  • Gel nomenclature 2
  • White balancing cameras 3
  • References 4

Correlated color temperature

Chromaticity diagram, Planckian locus, and lines of constant CCT.

The particular color of a white light source can be simplified into a correlated color temperature (CCT). The higher the CCT, the bluer the light appears. Sunlight at 5600K for example appears much bluer than tungsten light at 3200K. Unlike a chromaticity diagram, the Kelvin scale reduces the light source's color into one dimension. Thus, light sources of the same CCT may appear green or magenta in comparison with one another [3]. Fluorescent lights for example are typically very green in comparison with other types of lighting. However, some fluorescents are designed to have a high faithfulness to an ideal light, as measured by its color rendering index (CRI). This dimension, along lines of constant CCT, is sometimes measured in terms of green–magenta balance;[1] this dimension is sometimes referred to as "tint" or "CC".

Gel nomenclature

The main color correction gels are CTB (color temperature blue) and CTO (color temperature orange). A CTB gel converts tungsten light of 3200K to 'daylight' color (5200K). A CTO gel performs the reverse.[2] Note that different manufacturers' gels yield slightly different colors. As well, there is no precise definition of the color of daylight since it varies depending on the location (latitude, dust, pollution) and the time of day.

Gels that remove the green cast of fluorescent lights are called minus green. Gels that add a green cast are called plus green.[2] Fractions such as 3/4, 1/2, 1/4, and 1/8 indicate the strength of a gel. A 1/2 CTO gel is half the strength of a (full) CTO gel.

White balancing cameras

Color filters may be applied over a camera lens to adjust its white balance. In video systems, white balance can be achieved by digital or electronic manipulation of the signal and hence color correction filters are not entirely necessary. However, some digital cinema cameras can record an image without any digital filtering applied. Using physical color correction filters to white balance (instead of digital or electronic manipulation) can maximize the dynamic range of the captured image [4].

Some professional cameras designed for ENG use filter wheels containing color correction filters and are designed to optimize performance for different color temperatures.

In film cameras, no electronic or digital manipulation of white balance is possible in the original camera negative. Color correction filters are an effective method of adjusting white balance. Without filtering, one must attempt to fix white balance through color timing or by manipulating the film after it has been scanned or telecined.


  1. ^ "TLS,Inc. Technical Library - Filter Facts". 
  2. ^ a b John Jackman (2004). Lighting for Digital Video and Television (second ed.). Focal Press.  
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.