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This article is about the process applied to still images. For the equivalent process applied to video, see Color grading.

In photography and image processing, color balance is the global adjustment of the intensities of the colors (typically red, green, and blue primary colors). An important goal of this adjustment is to render specific colors – particularly neutral colors – correctly. Hence, the general method is sometimes called gray balance, neutral balance, or white balance. Color balance changes the overall mixture of colors in an image and is used for color correction. Generalized versions of color balance are used to correct colors other than neutrals or to deliberately change them for effect. The term white balance is called that way due to the nature of the adjustment in which colors are adjusted to make a white object (such as a piece of paper or a wall) appear white and not bluish or reddish.

The left half shows the photo as it came from the digital camera. The right half shows the photo adjusted to make a gray surface neutral in the same light.

Image data acquired by sensors – either film or electronic image sensors – must be transformed from the acquired values to new values that are appropriate for color reproduction or display. Several aspects of the acquisition and display process make such color correction essential – including that the acquisition sensors do not match the sensors in the human eye, that the properties of the display medium must be accounted for, and that the ambient viewing conditions of the acquisition differ from the display viewing conditions.

The color balance operations in popular image editing applications usually operate directly on the red, green, and blue channel pixel values, without respect to any color sensing or reproduction model. In film photography, color balance is typically achieved by using color correction filters over the lights or on the camera lens.

Contents

Example of color balancing

Sometimes the adjustment to keep neutrals neutral is called white balance, and the phrase color balance refers to the adjustment that in addition makes other colors in a displayed image appear to have the same general appearance as the colors in an original scene. It is particularly important that neutral (gray, neutral, white) colors in a scene appear neutral in the reproduction.

Psychological color balance

Humans relate to flesh tones more critically than other colors. Trees, grass and sky can all be off without concern, but if human flesh tones are 'off' then the human subject can look sick or dead. To address this critical color balance issue, the tri-color primaries themselves are formulated to not balance as a true neutral color. The purpose of this color primary imbalance is to more faithfully reproduce the flesh tones through the entire brightness range.

A seascape photograph at Clifton Beach, South Arm, Tasmania, Australia. The white balance has been adjusted towards the warm side for creative effect.
Photograph of a ColorChecker as a reference shot for color balance adjustments.
Two photos of a high-rise building shot within a minute of each other with an entry-level point-and-shoot camera. Left photo shows a "normal", more accurate color balance, while the right side shows a "vivid" color balance, in-camera effects and no post-production besides black background.
Comparison of color versions (raw, natural, white balance) of Mount Sharp (Aeolis Mons) on Mars
A white-balanced image of Mount Sharp (Aeolis Mons) on Mars

Most digital cameras have means to select color correction based on the type of scene lighting, using either manual lighting selection, automatic white balance, or custom white balance. The algorithms for these processes perform generalized chromatic adaptation.

Many methods exist for color balancing. Setting a button on a camera is a way for the user to indicate to the processor the nature of the scene lighting. Another option on some cameras is a button which one may press when the camera is pointed at a gray card or other neutral colored object. This captures an image of the ambient light, which enables a digital camera to set the correct color balance for that light.

There is a large literature on how one might estimate the ambient lighting from the camera data and then use this information to transform the image data. A variety of algorithms have been proposed, and the quality of these has been debated. A few examples and examination of the references therein will lead the reader to many others. Examples are Retinex, an artificial neural network or a Bayesian method.

Color balancing an image affects not only the neutrals, but other colors as well. An image that is not color balanced is said to have a color cast, as everything in the image appears to have been shifted towards one color.[page needed] Color balancing may be thought in terms of removing this color cast.

Color balance is also related to color constancy. Algorithms and techniques used to attain color constancy are frequently used for color balancing, as well. Color constancy is, in turn, related to chromatic adaptation. Conceptually, color balancing consists of two steps: first, determining the illuminant under which an image was captured; and second, scaling the components (e.g., R, G, and B) of the image or otherwise transforming the components so they conform to the viewing illuminant.

Viggiano found that white balancing in the camera's native RGB color model tended to produce less color inconstancy (i.e., less distortion of the colors) than in monitor RGB for over 4000 hypothetical sets of camera sensitivities. This difference typically amounted to a factor of more than two in favor of camera RGB. This means that it is advantageous to get color balance right at the time an image is captured, rather than edit later on a monitor. If one must color balance later, balancing the raw image data will tend to produce less distortion of chromatic colors than balancing in monitor RGB.

Color balancing is sometimes performed on a three-component image (e.g., RGB) using a 3x3 matrix. This type of transformation is appropriate if the image was captured using the wrong white balance setting on a digital camera, or through a color filter.

Scaling monitor R, G, and B

In principle, one wants to scale all relative luminances in an image so that objects which are believed to be neutral appear so. If, say, a surface with R = 240 {\displaystyle R=240} was believed to be a white object, and if 255 is the count which corresponds to white, one could multiply all red values by 255/240. Doing analogously for green and blue would result, at least in theory, in a color balanced image. In this type of transformation the 3x3 matrix is a diagonal matrix.

[ R G B ] = [ 255 / R w 0 0 0 255 / G w 0 0 0 255 / B w ] [ R G B ] {\displaystyle \left[{\begin{array}{c}R\\G\\B\end{array}}\right]=\left[{\begin{array}{ccc}255/R'_{w}&0&0\\0&255/G'_{w}&0\\0&0&255/B'_{w}\end{array}}\right]\left[{\begin{array}{c}R'\\G'\\B'\end{array}}\right]}

where R {\displaystyle R} , G {\displaystyle G} , and B {\displaystyle B} are the color balanced red, green, and blue components of a pixel in the image; R {\displaystyle R'} , G {\displaystyle G'} , and B {\displaystyle B'} are the red, green, and blue components of the image before color balancing, and R w {\displaystyle R'_{w}} , G w {\displaystyle G'_{w}} , and B w {\displaystyle B'_{w}} are the red, green, and blue components of a pixel which is believed to be a white surface in the image before color balancing. This is a simple scaling of the red, green, and blue channels, and is why color balance tools in Photoshop and the GIMP have a white eyedropper tool. It has been demonstrated that performing the white balancing in the phosphor set assumed by sRGB tends to produce large errors in chromatic colors, even though it can render the neutral surfaces perfectly neutral.

Scaling X, Y, Z

If the image may be transformed into CIE XYZ tristimulus values, the color balancing may be performed there. This has been termed a “wrong von Kries” transformation. Although it has been demonstrated to offer usually poorer results than balancing in monitor RGB, it is mentioned here as a bridge to other things. Mathematically, one computes:

[ X Y Z ] = [ X w / X w 0 0 0 Y w / Y w 0 0 0 Z w / Z w ] [ X Y Z ] {\displaystyle \left[{\begin{array}{c}X\\Y\\Z\end{array}}\right]=\left[{\begin{array}{ccc}X_{w}/X'_{w}&0&0\\0&Y_{w}/Y'_{w}&0\\0&0&Z_{w}/Z'_{w}\end{array}}\right]\left[{\begin{array}{c}X'\\Y'\\Z'\end{array}}\right]}

where X {\displaystyle X} , Y {\displaystyle Y} , and Z {\displaystyle Z} are the color-balanced tristimulus values; X w {\displaystyle X_{w}} , Y w {\displaystyle Y_{w}} , and Z w {\displaystyle Z_{w}} are the tristimulus values of the viewing illuminant (the white point to which the image is being transformed to conform to); X w {\displaystyle X'_{w}} , Y w {\displaystyle Y'_{w}} , and Z w {\displaystyle Z'_{w}} are the tristimulus values of an object believed to be white in the un-color-balanced image, and X {\displaystyle X'} , Y {\displaystyle Y'} , and Z {\displaystyle Z'} are the tristimulus values of a pixel in the un-color-balanced image. If the tristimulus values of the monitor primaries are in a matrix P {\displaystyle \mathbf {P} } so that:

[ X Y Z ] = P [ L R L G L B ] {\displaystyle \left[{\begin{array}{c}X\\Y\\Z\end{array}}\right]=\mathbf {P} \left[{\begin{array}{c}L_{R}\\L_{G}\\L_{B}\end{array}}\right]}

where L R {\displaystyle L_{R}} , L G {\displaystyle L_{G}} , and L B {\displaystyle L_{B}} are the un-gamma corrected monitor RGB, one may use:

[ L R L G L B ] = P 1 [ X w / X w 0 0 0 Y w / Y w 0 0 0 Z w / Z w ] P [ L R L G L B ] {\displaystyle \left[{\begin{array}{c}L_{R}\\L_{G}\\L_{B}\end{array}}\right]=\mathbf {P^{-1}} \left[{\begin{array}{ccc}X_{w}/X'_{w}&0&0\\0&Y_{w}/Y'_{w}&0\\0&0&Z_{w}/Z'_{w}\end{array}}\right]\mathbf {P} \left[{\begin{array}{c}L_{R'}\\L_{G'}\\L_{B'}\end{array}}\right]}

Von Kries's method

Johannes von Kries, whose theory of rods and three color-sensitive cone types in the retina has survived as the dominant explanation of color sensation for over 100 years, motivated the method of converting color to the LMS color space, representing the effective stimuli for the Long-, Medium-, and Short-wavelength cone types that are modeled as adapting independently. A 3x3 matrix converts RGB or XYZ to LMS, and then the three LMS primary values are scaled to balance the neutral; the color can then be converted back to the desired final color space:

[ L M S ] = [ 1 / L w 0 0 0 1 / M w 0 0 0 1 / S w ] [ L M S ] {\displaystyle \left[{\begin{array}{c}L\\M\\S\end{array}}\right]=\left[{\begin{array}{ccc}1/L'_{w}&0&0\\0&1/M'_{w}&0\\0&0&1/S'_{w}\end{array}}\right]\left[{\begin{array}{c}L'\\M'\\S'\end{array}}\right]}

where L {\displaystyle L} , M {\displaystyle M} , and S {\displaystyle S} are the color-balanced LMS cone tristimulus values; L w {\displaystyle L'_{w}} , M w {\displaystyle M'_{w}} , and S w {\displaystyle S'_{w}} are the tristimulus values of an object believed to be white in the un-color-balanced image, and L {\displaystyle L'} , M {\displaystyle M'} , and S {\displaystyle S'} are the tristimulus values of a pixel in the un-color-balanced image.

Matrices to convert to LMS space were not specified by von Kries, but can be derived from CIE color matching functions and LMS color matching functions when the latter are specified; matrices can also be found in reference books.

Scaling camera RGB

By Viggiano's measure, and using his model of gaussian camera spectral sensitivities, most camera RGB spaces performed better than either monitor RGB or XYZ. If the camera's raw RGB values are known, one may use the 3x3 diagonal matrix:

[ R G B ] = [ 255 / R w 0 0 0 255 / G w 0 0 0 255 / B w ] [ R G B ] {\displaystyle \left[{\begin{array}{c}R\\G\\B\end{array}}\right]=\left[{\begin{array}{ccc}255/R'_{w}&0&0\\0&255/G'_{w}&0\\0&0&255/B'_{w}\end{array}}\right]\left[{\begin{array}{c}R'\\G'\\B'\end{array}}\right]}

and then convert to a working RGB space such as sRGB or Adobe RGB after balancing.

Preferred chromatic adaptation spaces

Comparisons of images balanced by diagonal transforms in a number of different RGB spaces have identified several such spaces that work better than others, and better than camera or monitor spaces, for chromatic adaptation, as measured by several color appearance models; the systems that performed statistically as well as the best on the majority of the image test sets used were the "Sharp", "Bradford", "CMCCAT", and "ROMM" spaces.

General illuminant adaptation

The best color matrix for adapting to a change in illuminant is not necessarily a diagonal matrix in a fixed color space. It has long been known that if the space of illuminants can be described as a linear model with N basis terms, the proper color transformation will be the weighted sum of N fixed linear transformations, not necessarily consistently diagonalizable.

Examples

Neutral light
Warm light
Cold light
Comparison of resulted colors as shot by the digital camera for different light qualities (color temperature): Neutral, Warm and Cold.
Setting: As shot
Setting: Cloudy
Setting: Tungsten
Example of different white balance settings on digital camera for Neutral light.
  1. Phyllis Davis (2000). The Gimp for Linux and Unix. Peachpit Press. p. 134. ISBN 978-0-201-70253-8.
  2. Adobe Creative Team (2000). Adobe Photoshop 6.0. Adobe Press. p. 278. ISBN 978-0-201-71016-8.[need quotation to verify]
  3. Blain Brown (2002). Cinematography: Theory and Practice : Imagemaking for Cinematographers, Directors, and Videographers. Focal Press. p. 170. ISBN 978-0-240-80500-9.
  4. Hsien-Che Lee (2005).Introduction to Color Imaging Science. Cambridge University Press. p. 450. ISBN 978-0-521-84388-1.
  5. White Balance. Nikon Digital.Retrieved October 12, 2016.
  6. Afifi, Mahmoud; Price, Brian; Cohen, Scott; Brown, Michael S (2019). "When Color Constancy Goes Wrong: Correcting Improperly White-Balanced Images"(PDF). Proceedings of the IEEE Conference on Computer Vision and Pattern Recognition: 1535–1544. doi:10.1109/cvpr.2019.00163. ISBN 978-1-7281-3293-8. S2CID 196195956.
  7. Brian Funt, Vlad Cardei, and Kobus Barnard, "Learning color constancy," in Proceedings of the Fourth IS&T/SID Color Imaging Conference, pp. 58–60 (1996).
  8. Graham Finlayson; Paul M. Hubel; Steven Hordley (November 2001). "Color by correlation: a simple, unifying framework for color constancy"(PDF). IEEE Transactions on Pattern Analysis and Machine Intelligence. 23 (11): 1209–21. CiteSeerX10.1.1.133.2101. doi:10.1109/34.969113.
  9. John A C Yule, Principles of Color Reproduction. New York: Wiley, 1967.
  10. Viggiano, J A Stephen (2004). "Comparison of the accuracy of different white-balancing options as quantified by their color constancy". In Blouke, Morley M; Sampat, Nitin; Motta, Ricardo J (eds.). Sensors and Camera Systems for Scientific, Industrial, and Digital Photography Applications V. Vol. 5301. pp. 323–333. doi:10.1117/12.524922. S2CID 8971750.
  11. Heinz Terstiege (1972). "Chromatic adaptation: a state-of-the-art report". Journal of Color Appearance. 1 (4): 19–23 (cont. 40).
  12. Mark D Fairchild, Color Appearance Models. Reading, MA: Addison-Wesley, 1998.
  13. Gaurav Sharma (2003). Digital Color Imaging Handbook. CRC Press. p. 153. ISBN 978-0-8493-0900-7.
  14. Sabine Süsstrunk; Jack Holm; Graham D. Finlayson (January 2001). "Chromatic Adaptation Performance of Different RGB Sensors". IS&T/SPIE Electronic Imaging. 4300. doi:10.1117/12.410788. S2CID 8140548. Archived from the original on 2006-10-18. Retrieved2009-03-20.
  15. Laurence T. Maloney; Brain A. Wandell (1987). "Color constancy: a method for recovering surface spectral reflectance". In Martin A. Fischler; Oscar Firschein (eds.). Readings in Computer Vision. Morgan-Kaufmann. ISBN 978-0-934613-33-0.
  16. "photoskop: Interactive Photography Lessons". April 25, 2015.

Color balance Article Talk Language Watch Edit 160 160 Redirected from White balance This article is about the process applied to still images For the equivalent process applied to video see Color grading In photography and image processing color balance is the global adjustment of the intensities of the colors typically red green and blue primary colors An important goal of this adjustment is to render specific colors particularly neutral colors correctly Hence the general method is sometimes called gray balance neutral balance or white balance Color balance changes the overall mixture of colors in an image and is used for color correction Generalized versions of color balance are used to correct colors other than neutrals or to deliberately change them for effect The term white balance is called that way due to the nature of the adjustment in which colors are adjusted to make a white object such as a piece of paper or a wall appear white and not bluish or reddish The left half shows the photo as it came from the digital camera The right half shows the photo adjusted to make a gray surface neutral in the same light Image data acquired by sensors either film or electronic image sensors must be transformed from the acquired values to new values that are appropriate for color reproduction or display Several aspects of the acquisition and display process make such color correction essential including that the acquisition sensors do not match the sensors in the human eye that the properties of the display medium must be accounted for and that the ambient viewing conditions of the acquisition differ from the display viewing conditions The color balance operations in popular image editing applications usually operate directly on the red green and blue channel pixel values 1 2 without respect to any color sensing or reproduction model In film photography color balance is typically achieved by using color correction filters over the lights or on the camera lens 3 Contents 1 Generalized color balance 1 1 Psychological color balance 2 Illuminant estimation and adaptation 3 Chromatic colors 4 Mathematics of color balance 4 1 Scaling monitor R G and B 4 2 Scaling X Y Z 4 3 Von Kries s method 4 4 Scaling camera RGB 4 5 Preferred chromatic adaptation spaces 4 6 General illuminant adaptation 4 7 Examples 5 See also 6 References 7 External linksGeneralized color balance Edit Example of color balancing Sometimes the adjustment to keep neutrals neutral is called white balance and the phrase color balance refers to the adjustment that in addition makes other colors in a displayed image appear to have the same general appearance as the colors in an original scene 4 It is particularly important that neutral gray neutral white colors in a scene appear neutral in the reproduction 5 Psychological color balance Edit Humans relate to flesh tones more critically than other colors Trees grass and sky can all be off without concern but if human flesh tones are off then the human subject can look sick or dead To address this critical color balance issue the tri color primaries themselves are formulated to not balance as a true neutral color The purpose of this color primary imbalance is to more faithfully reproduce the flesh tones through the entire brightness range Illuminant estimation and adaptation Edit A seascape photograph at Clifton Beach South Arm Tasmania Australia The white balance has been adjusted towards the warm side for creative effect Photograph of a ColorChecker as a reference shot for color balance adjustments Two photos of a high rise building shot within a minute of each other with an entry level point and shoot camera Left photo shows a normal more accurate color balance while the right side shows a vivid color balance in camera effects and no post production besides black background Comparison of color versions raw natural white balance of Mount Sharp Aeolis Mons on Mars A white balanced image of Mount Sharp Aeolis Mons on Mars Most digital cameras have means to select color correction based on the type of scene lighting using either manual lighting selection automatic white balance or custom white balance 6 The algorithms for these processes perform generalized chromatic adaptation Many methods exist for color balancing Setting a button on a camera is a way for the user to indicate to the processor the nature of the scene lighting Another option on some cameras is a button which one may press when the camera is pointed at a gray card or other neutral colored object This captures an image of the ambient light which enables a digital camera to set the correct color balance for that light There is a large literature on how one might estimate the ambient lighting from the camera data and then use this information to transform the image data A variety of algorithms have been proposed and the quality of these has been debated A few examples and examination of the references therein will lead the reader to many others Examples are Retinex an artificial neural network 7 or a Bayesian method 8 Chromatic colors EditColor balancing an image affects not only the neutrals but other colors as well An image that is not color balanced is said to have a color cast as everything in the image appears to have been shifted towards one color 9 page needed Color balancing may be thought in terms of removing this color cast Color balance is also related to color constancy Algorithms and techniques used to attain color constancy are frequently used for color balancing as well Color constancy is in turn related to chromatic adaptation Conceptually color balancing consists of two steps first determining the illuminant under which an image was captured and second scaling the components e g R G and B of the image or otherwise transforming the components so they conform to the viewing illuminant Viggiano found that white balancing in the camera s native RGB color model tended to produce less color inconstancy i e less distortion of the colors than in monitor RGB for over 4000 hypothetical sets of camera sensitivities 10 This difference typically amounted to a factor of more than two in favor of camera RGB This means that it is advantageous to get color balance right at the time an image is captured rather than edit later on a monitor If one must color balance later balancing the raw image data will tend to produce less distortion of chromatic colors than balancing in monitor RGB Mathematics of color balance EditColor balancing is sometimes performed on a three component image e g RGB using a 3x3 matrix This type of transformation is appropriate if the image was captured using the wrong white balance setting on a digital camera or through a color filter Scaling monitor R G and B Edit In principle one wants to scale all relative luminances in an image so that objects which are believed to be neutral appear so If say a surface with R 240 displaystyle R 240 was believed to be a white object and if 255 is the count which corresponds to white one could multiply all red values by 255 240 Doing analogously for green and blue would result at least in theory in a color balanced image In this type of transformation the 3x3 matrix is a diagonal matrix R G B 255 R w 0 0 0 255 G w 0 0 0 255 B w R G B displaystyle left begin array c R G B end array right left begin array ccc 255 R w amp 0 amp 0 0 amp 255 G w amp 0 0 amp 0 amp 255 B w end array right left begin array c R G B end array right where R displaystyle R G displaystyle G and B displaystyle B are the color balanced red green and blue components of a pixel in the image R displaystyle R G displaystyle G and B displaystyle B are the red green and blue components of the image before color balancing and R w displaystyle R w G w displaystyle G w and B w displaystyle B w are the red green and blue components of a pixel which is believed to be a white surface in the image before color balancing This is a simple scaling of the red green and blue channels and is why color balance tools in Photoshop and the GIMP have a white eyedropper tool It has been demonstrated that performing the white balancing in the phosphor set assumed by sRGB tends to produce large errors in chromatic colors even though it can render the neutral surfaces perfectly neutral 10 Scaling X Y Z Edit If the image may be transformed into CIE XYZ tristimulus values the color balancing may be performed there This has been termed a wrong von Kries transformation 11 12 Although it has been demonstrated to offer usually poorer results than balancing in monitor RGB it is mentioned here as a bridge to other things Mathematically one computes X Y Z X w X w 0 0 0 Y w Y w 0 0 0 Z w Z w X Y Z displaystyle left begin array c X Y Z end array right left begin array ccc X w X w amp 0 amp 0 0 amp Y w Y w amp 0 0 amp 0 amp Z w Z w end array right left begin array c X Y Z end array right where X displaystyle X Y displaystyle Y and Z displaystyle Z are the color balanced tristimulus values X w displaystyle X w Y w displaystyle Y w and Z w displaystyle Z w are the tristimulus values of the viewing illuminant the white point to which the image is being transformed to conform to X w displaystyle X w Y w displaystyle Y w and Z w displaystyle Z w are the tristimulus values of an object believed to be white in the un color balanced image and X displaystyle X Y displaystyle Y and Z displaystyle Z are the tristimulus values of a pixel in the un color balanced image If the tristimulus values of the monitor primaries are in a matrix P displaystyle mathbf P so that X Y Z P L R L G L B displaystyle left begin array c X Y Z end array right mathbf P left begin array c L R L G L B end array right where L R displaystyle L R L G displaystyle L G and L B displaystyle L B are the un gamma corrected monitor RGB one may use L R L G L B P 1 X w X w 0 0 0 Y w Y w 0 0 0 Z w Z w P L R L G L B displaystyle left begin array c L R L G L B end array right mathbf P 1 left begin array ccc X w X w amp 0 amp 0 0 amp Y w Y w amp 0 0 amp 0 amp Z w Z w end array right mathbf P left begin array c L R L G L B end array right Von Kries s method Edit Johannes von Kries whose theory of rods and three color sensitive cone types in the retina has survived as the dominant explanation of color sensation for over 100 years motivated the method of converting color to the LMS color space representing the effective stimuli for the Long Medium and Short wavelength cone types that are modeled as adapting independently A 3x3 matrix converts RGB or XYZ to LMS and then the three LMS primary values are scaled to balance the neutral the color can then be converted back to the desired final color space 13 L M S 1 L w 0 0 0 1 M w 0 0 0 1 S w L M S displaystyle left begin array c L M S end array right left begin array ccc 1 L w amp 0 amp 0 0 amp 1 M w amp 0 0 amp 0 amp 1 S w end array right left begin array c L M S end array right where L displaystyle L M displaystyle M and S displaystyle S are the color balanced LMS cone tristimulus values L w displaystyle L w M w displaystyle M w and S w displaystyle S w are the tristimulus values of an object believed to be white in the un color balanced image and L displaystyle L M displaystyle M and S displaystyle S are the tristimulus values of a pixel in the un color balanced image Matrices to convert to LMS space were not specified by von Kries but can be derived from CIE color matching functions and LMS color matching functions when the latter are specified matrices can also be found in reference books 13 Scaling camera RGB Edit By Viggiano s measure and using his model of gaussian camera spectral sensitivities most camera RGB spaces performed better than either monitor RGB or XYZ 10 If the camera s raw RGB values are known one may use the 3x3 diagonal matrix R G B 255 R w 0 0 0 255 G w 0 0 0 255 B w R G B displaystyle left begin array c R G B end array right left begin array ccc 255 R w amp 0 amp 0 0 amp 255 G w amp 0 0 amp 0 amp 255 B w end array right left begin array c R G B end array right and then convert to a working RGB space such as sRGB or Adobe RGB after balancing Preferred chromatic adaptation spaces Edit Comparisons of images balanced by diagonal transforms in a number of different RGB spaces have identified several such spaces that work better than others and better than camera or monitor spaces for chromatic adaptation as measured by several color appearance models the systems that performed statistically as well as the best on the majority of the image test sets used were the Sharp Bradford CMCCAT and ROMM spaces 14 General illuminant adaptation Edit The best color matrix for adapting to a change in illuminant is not necessarily a diagonal matrix in a fixed color space It has long been known that if the space of illuminants can be described as a linear model with N basis terms the proper color transformation will be the weighted sum of N fixed linear transformations not necessarily consistently diagonalizable 15 Examples Edit Neutral light Warm light Cold lightComparison of resulted colors as shot by the digital camera for different light qualities color temperature Neutral Warm and Cold 16 Setting As shot Setting Cloudy Setting TungstenExample of different white balance settings on digital camera for Neutral light 16 See also EditColor cast Color temperature Gamma correction White pointReferences Edit Phyllis Davis 2000 The Gimp for Linux and Unix Peachpit Press p 134 ISBN 978 0 201 70253 8 Adobe Creative Team 2000 Adobe Photoshop 6 0 Adobe Press p 278 ISBN 978 0 201 71016 8 need quotation to verify Blain Brown 2002 Cinematography Theory and Practice Imagemaking for Cinematographers Directors and Videographers Focal Press p 170 ISBN 978 0 240 80500 9 Hsien Che Lee 2005 Introduction to Color Imaging Science Cambridge University Press p 450 ISBN 978 0 521 84388 1 White Balance Nikon Digital Retrieved October 12 2016 Afifi Mahmoud Price Brian Cohen Scott Brown Michael S 2019 When Color Constancy Goes Wrong Correcting Improperly White Balanced Images PDF Proceedings of the IEEE Conference on Computer Vision and Pattern Recognition 1535 1544 doi 10 1109 cvpr 2019 00163 ISBN 978 1 7281 3293 8 S2CID 196195956 Brian Funt Vlad Cardei and Kobus Barnard Learning color constancy in Proceedings of the Fourth IS amp T SID Color Imaging Conference pp 58 60 1996 Graham Finlayson Paul M Hubel Steven Hordley November 2001 Color by correlation a simple unifying framework for color constancy PDF IEEE Transactions on Pattern Analysis and Machine Intelligence 23 11 1209 21 CiteSeerX 10 1 1 133 2101 doi 10 1109 34 969113 John A C Yule Principles of Color Reproduction New York Wiley 1967 a b c Viggiano J A Stephen 2004 Comparison of the accuracy of different white balancing options as quantified by their color constancy In Blouke Morley M Sampat Nitin Motta Ricardo J eds Sensors and Camera Systems for Scientific Industrial and Digital Photography Applications V Vol 5301 pp 323 333 doi 10 1117 12 524922 S2CID 8971750 Heinz Terstiege 1972 Chromatic adaptation a state of the art report Journal of Color Appearance 1 4 19 23 cont 40 Mark D Fairchild Color Appearance Models Reading MA Addison Wesley 1998 a b Gaurav Sharma 2003 Digital Color Imaging Handbook CRC Press p 153 ISBN 978 0 8493 0900 7 Sabine Susstrunk Jack Holm Graham D Finlayson January 2001 Chromatic Adaptation Performance of Different RGB Sensors IS amp T SPIE Electronic Imaging 4300 doi 10 1117 12 410788 S2CID 8140548 Archived from the original on 2006 10 18 Retrieved 2009 03 20 Laurence T Maloney Brain A Wandell 1987 Color constancy a method for recovering surface spectral reflectance In Martin A Fischler Oscar Firschein eds Readings in Computer Vision Morgan Kaufmann ISBN 978 0 934613 33 0 a b photoskop Interactive Photography Lessons April 25 2015 External links EditWhite Balance Intro at nikondigital org photoskop Interactive Photography Lessons Interactive White Balance Understanding White Balance Tutorial Affine color balance with saturation with code and on line demonstration Getting the White Balance Right for Neutral Colors Photography Tutorial Retrieved from https en wikipedia org w index php title Color balance amp oldid 1071984057, wikipedia, wiki, book,

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