Chromatic aberration - Revision history

Zarl: Reverted edits by Ularedmond (Talk) to last version by Erik Krause

2011-09-23T15:07:02Z

Reverted edits by Ularedmond (Talk) to last version by Erik Krause

Ularedmond at 13:58, 23 September 2011

2011-09-23T13:58:34Z

Erik Krause: /* Strange Example */

2010-05-03T19:46:34Z

‎Strange Example

Erik Krause: /* External links */ typo

2007-12-02T18:04:08Z

‎External links: typo

Erik Krause: /* External links */ linked to M.Thoby

2007-12-02T18:02:43Z

‎External links: linked to M.Thoby

Erik Krause: /* TCA */ clarified

2007-12-02T17:59:41Z

‎TCA: clarified

Erik Krause: interwiki linked

2007-11-20T16:45:06Z

interwiki linked

Erik Krause: Prepared for new glossary template

2007-11-17T22:14:53Z

Prepared for new glossary template

Erik Krause: /* Precise */ mentioned octave script

2007-11-04T15:10:41Z

‎Precise: mentioned octave script

Erik Krause: /* Precise */ linked octave

2007-11-04T15:03:06Z

‎Precise: linked octave

← Older revision		Revision as of 15:07, 23 September 2011
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	[[Category:Tutorial:Nice to know]]		[[Category:Tutorial:Nice to know]]
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← Older revision		Revision as of 13:58, 23 September 2011
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	[[Category:Glossary]]		[[Category:Glossary]]
	[[Category:Tutorial:Nice to know]]		[[Category:Tutorial:Nice to know]]
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 [[image:CA_strange02.jpg]]
-This weird kind of colored fringes is definitely not lens CA. I can only think of some effects with the microlenses Nikon placed in front of each sensor pixel, but this is wild guess.
+This weird kind of colored fringes is definitely not lens CA. I can only think of some effects of bayer interpolation, but this is wild guess.
 == How to correct ==

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 * [[wikipedia:Chromatic aberration|Wikipedia:Chromatic aberration]]
 * [http://www.dpreview.com/learn/?/Glossary/Optical/chromatic_aberration_01.htm dpreview on chromatic aberration]
-* [http://michel.thoby.free.fr/Compare_Fisheyes/Correction_TCA/Illusion_and_reality_TCA.html Michel Thoby's article Illusion and reality - How does TCA look like?
+* Michel Thoby's article [http://michel.thoby.free.fr/Compare_Fisheyes/Correction_TCA/Illusion_and_reality_TCA.html Illusion and reality - How does TCA look like?]
 [[Category:Glossary]]
 [[Category:Tutorial:Nice to know]]

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 * [[wikipedia:Chromatic aberration|Wikipedia:Chromatic aberration]]
 * [http://www.dpreview.com/learn/?/Glossary/Optical/chromatic_aberration_01.htm dpreview on chromatic aberration]
 [[Category:Glossary]]
 [[Category:Tutorial:Nice to know]]

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 When a lens is corrected for longitudinal chromatic aberration, different colors focus more or less in the same point on the optical axis, but they might focus in different distances off axis resulting in images of different size for different colors. This type is called lateral or <b>transverse chromatic aberration</b> (TCA). If you have complementary colored fringes progressively more from the center to the corners, this is most likely transverse chromatic aberration (although there are some exceptions as the [[#Strange Example|example]] below illustrates). This type:
 *can be corrected by software
-*does not change by stopping down.
+*does not change by stopping down (stopping down would perhaps make the fringes sharper and lead to the impression TCA is reduced)
 *is dependent from focus distance.

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 == What it is ==
-Chromatic aberration is a common lens error visible in images as colored fringes or colored blur along edges. It is caused by a different refractive index of glass for light at different wavelength. There is a nice description with lots of links on [http://en.wikipedia.org/wiki/Chromatic_aberration Wikipedia].
+Chromatic aberration is a common lens error visible in images as colored fringes or colored blur along edges. It is caused by a different refractive index of glass for light at different wavelength. There is a nice description with lots of links on [[wikipedia:Chromatic aberration]].
 Another good description is found on [http://www.vanwalree.com/optics/chromatic.html Paul van Walree's] page.

← Older revision		Revision as of 22:14, 17 November 2007
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		+	{{Glossary\|A type of lens error generating colored fringes.}}
	== Intro ==		== Intro ==
	Color fringes can be very annoying, especially in stitched panoramas. Since they often appear nearer to the edges of single images they are near to any seam between two images in the panorama. Even worse, they change color where they cross the seam.		Color fringes can be very annoying, especially in stitched panoramas. Since they often appear nearer to the edges of single images they are near to any seam between two images in the panorama. Even worse, they change color where they cross the seam.

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 Based on this work [http://www.pinlady.net/vr/ Eric Gerds] developed a Photoshop CS Javascript called [[PTShift]] that allows for manual correction in different areas and passes the found deviations as virtual control points to [[PTOptimizer]] in order to calculate correction coefficients.
-Alternatively the correction coefficients can be calculated entirely with [[hugin]] and [[PTOptimizer]], for more details see this [http://hugin.sourceforge.net/tutorials/tca/ hugin tutorial on correcting TCA].  For more precise results, [http://www.gnu.org/software/octave/ octave] can be used to calculate the coefficients rather than [[PTOptimizer]].  An alternative to the [[Panorama Tools Plugins#Radial Shift|Radial Shift]] filter is [[fulla]] which can also correct TCA, [[barrel distortion]] and [[vignetting]] at the same time.
+Alternatively the correction coefficients can be calculated entirely with [[hugin]] and [[PTOptimizer]], for more details see this [http://hugin.sourceforge.net/tutorials/tca/ hugin tutorial on correcting TCA].  For more precise results, [http://www.gnu.org/software/octave/ octave] (script on the hugin page: [http://hugin.sourceforge.net/tutorials/tca/en.shtml]) can be used to calculate the coefficients rather than [[PTOptimizer]].  An alternative to the [[Panorama Tools Plugins#Radial Shift|Radial Shift]] filter is [[fulla]] which can also correct TCA, [[barrel distortion]] and [[vignetting]] at the same time.
 <small>[[User:Erik Krause|Erik Krause]] 17:18, 2 May 2005 (EDT)</small>