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(12) United States Patent (10) Patent No.: US 8,339.462 B2 Stec Et Al

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(12) United States Patent (10) Patent No.: US 8,339.462 B2 Stec Et Al US0083394.62B2 (12) United States Patent (10) Patent No.: US 8,339.462 B2 Stec et al. (45) Date of Patent: Dec. 25, 2012 (54) METHODS AND APPARATUSES FOR 6,881,718 B1 4/2005 FitzGerald et al. ADDRESSING CHROMATIC ABBERATIONS 7,003,139 B2 2/2006 Endrikhovski et al. 7,046,924 B2 5/2006 Miller et al. ANDPURPLE FRINGING 7,142,238 B1 * 1 1/2006 Sawada et al. ................ 348,252 7,206,022 B2 4/2007 Miller et al. (75) Inventors: Piotr Stec, Galway (IE); Larry Murray, 7,218,793 B2 5/2007 Perlmutter et al. Galway (IE); Alexandru Drimbarean, 7,233,684 B2 6/2007 Fedorovskaya et al. Galway (IE) 7,243,945 B2 7/2007 Breed et al. 7.245,319 B1* 7/2007 Enomoto ................... 348.222.1 (73) Assignee: DigitalOptics Corporation Europe (Continued) Limited, Galway (IE) FOREIGN PATENT DOCUMENTS (*) Notice: Subject to any disclaimer, the term of this EP 22.93582 A2 3, 2011 patent is extended or adjusted under 35 (Continued) U.S.C. 154(b) by 463 days. (21) Appl. No.: 12/360,665 OTHER PUBLICATIONS PCT Notification of Transmittal of the International Search Report (22) Filed: Jan. 27, 2009 and Written Opinion of the International Searching Authority, or the O O Declaration, for PCT Application No. PCT/EP2009/050967, mailed (65) Prior Publication Data on Oct. 16, 2009, 12 pages. US 2009/O189997 A1 Jul. 30, 2009 (Continued) Relatede U.S. Applicationpplication DatUata Primary Examiner — Albert Cutler (60) Provisional application No. 61/023,946, filed on Jan. (74) Attorney, Agent, or Firm — Andrew V. Smith 28, 2008, provisional application No. 61/024,274, filed on Jan. 29, 2008. (57) ABSTRACT (51) Int. Cl. Methods and systems for detecting and correcting chromatic H04N 7/00 (2006.01) aberration and purppurple fringingglng are disclosed. Chromatic aber H04N 7/02 (2006.01) ration can be addressed by separating an image into color H04N 5/228 (2006.01) planes and then adjusting these to reduce chromatic aberra (52) U.S. Cl. ..................................... 348/187, 348/222.1 tion by using a specific calibration image (calibration chart) (58) Field of Classification Search s 3487187 as an empirical method to calibrate the image acquisition - - - - - - - - - - - - - - - - - - 348/1 88 device. Purple fringing can be corrected by initially address S lication file f let h historv. ing coloraberration resulting from the lateral chromatic aber ee appl1cauon Ille Ior complete searcn n1Story ration (LCA). The LCA is first removed and then the correc (56) References Cited tion is extended to purple fringing. A discovery is relied upon that the purple fringing is created in the direction of the U.S. PATENT DOCUMENTS chromatic aberration and is more pronounced in the direction of the chromatic aberration. 5,315,413 A 5, 1994 Yamamoto et al. 5,477,345 A 12, 1995 Tse 6,466.232 B1 10/2002 Newell et al. 30 Claims, 11 Drawing Sheets 6,874,127 B2 3/2005 Newell et al. (11 of 11 Drawing Sheet(s) Filed in Color) US 8,339.462 B2 Page 2 U.S. PATENT DOCUMENTS WO 2007/079039 A2 7/2007 7,271,809 B2 9/2007 Fedorovskaya et al. W. 3988: A. S38 7.283,162 B2 10/2007 Silverbrook et al. 7.307,636 B2 12/2007 Matraszek et al. 7,319,780 B2 1/2008 Fedorovskaya et al. OTHER PUBLICATIONS 7,327,505 B2 2/2008 Fedorovskaya et al. 7,327,890 B2 2/2008 Fredlund John Mallon et al., Calibration and removal of lateral chromatic 7,349,010 B2 3/2008 Bryant et al. aberration in images, Pattern Recognition Letters, 2007, pp. 125-135, 7,369,164 B2 5, 2008 Parulski et al. vol. 28—Issue 1 7,369,917 B2 5, 2008 Ravish et al. 7,577,292 B2 8/2009 Kang PCT Partial International Search Report for Application No. PCT/ 8,089,555 B2 * 1/2012 Vakrat et al. .................. 348/360 EP2009/050967, dated Jul. 31, 2009, 4 pages. 2002/0051639 A1 5/2002 Enomoto ...................... 396,311 International Preliminary Report on Patentability Chapter I, for PCT 2003.0128389 A1 7/2003 Matraszek et al. Application No. No. PCT/EP2009/050967, dated Aug. 3, 2010, 8 2003/0206179 A1 1 1/2003 Deering pageS. 2004/0101212 A1 5/2004 Fedorovskaya et al. Written Opinion of the International Search Authority, for PCT 2006/0256382 A1 11/2006 Matraszek et al. Application No. No. PCT/EP2009/050967, dated May 25, 2011, 7 2007/0166025 A1 7/2007 Chang pplication No. No. , dated May Z, 2007/0201731 A1 8/2007 Fedorovskaya et al. pageS. 2007/0242945 A1 10, 2007 Fredlund et al. Patent Abstracts of Japan, publication No. 2006-115039, published on Apr. 27, 2006, Image Processor, Image Processing Method and FOREIGN PATENT DOCUMENTS Computer Program. JP 2006-115039 A 4/2006 JP 2009-522869. A 6, 2009 * cited by examiner U.S. Patent Dec. 25, 2012 Sheet 1 of 11 US 8,339.462 B2 Y Y Y FG. A (Prior Art F.G. B. {ior Art F.G. C F.G. D. (Prior Art U.S. Patent Dec. 25, 2012 Sheet 2 of 11 US 8,339.462 B2 FG, 2A F.G. B. Prior Art (Prior Art FG, C (Prior Art U.S. Patent Dec. 25, 2012 Sheet 3 of 11 US 8,339.462 B2 G. 3A G. 33. (Prior Art 8 8 FG, 3C FG 3) (Prior Art) U.S. Patent Dec. 25, 2012 Sheet 4 of 11 US 8,339.462 B2 U.S. Patent Dec. 25, 2012 Sheet 5 of 11 US 8,339.462 B2 *... :: U.S. Patent Dec. 25, 2012 Sheet 6 of 11 US 8,339.462 B2 ... : ... :: U.S. Patent Dec. 25, 2012 Sheet 7 of 11 US 8,339.462 B2 {..., x: ... xix. U.S. Patent Dec. 25, 2012 Sheet 8 of 11 US 8,339.462 B2 FG, 6A (Prior Art F.G. B. (Prior Art U.S. Patent Dec. 25, 2012 Sheet 9 of 11 US 8,339.462 B2 U.S. Patent Dec. 25, 2012 Sheet 10 of 11 US 8,339.462 B2 §§§ U.S. Patent Dec. 25, 2012 Sheet 11 of 11 US 8,339.462 B2 US 8,339,462 B2 1. 2 METHODS AND APPARATUSES FOR optical axis, but displaced in the longitudinal direction (i.e. ADDRESSING CHROMATIC ABBERATIONS along the axis). This behavior is elucidated in FIGS. 1A-1B ANDPURPLE FRINGING for a distant light source. In this sketch, only the green light is in sharp focus on the sensor. The blue and red light have a RELATED APPLICATIONS so-called circle of confusion in the sensor plane and are not sharply imaged. FIG.1B illustrates the origins of longitudinal This application claims the benefit of priority to U.S. pro chromatic aberration. FIG. 1B shows that focal planes of visional patent application No. 61/023,946, filed Jan. 28, three of the various colors do not coincide. 2008, entitled, “Methods and Apparatuses For Addressing In practical applications if there is a fringe near the image Chromatic Aberrations and Purple Fringing,” and U.S. pro 10 center that changes color if when the image is defocused visional patent application No. 61/024,274, filed Jan. 29, slightly, this is most likely longitudinal chromatic aberration. 2008, entitled, “Methods and Apparatuses for Addressing This type cannot be corrected using conventional Software, it Purple Fringing,” which are hereby incorporated by refer decreases if stopped down, and it is dependent from focus CCC. 15 distance. FIELD Lateral Chromatic Aberrations Embodiments of the invention relate generally to the field of correcting chromatic aberrations and purple fringing in Obliquely incident light leads to the transverse chromatic digital images. aberration, also known as lateral color. It refers to sideward displaced foci. In the absence of axial color, all colors are in BACKGROUND focus in the same plane, but the image magnification depends on the wavelength. The occurrence of lateral color implies The refractive index of any medium other than a vacuum that the focal length depends on the wavelength, whereas the varies with wavelength. Thus the Gaussian and aberrational 25 occurrence of axial color in a complex lens does not strictly properties of any refracting optical system are functions of require a variable focal length. This seems counterintuitive, wavelength, i.e. Chromatic aberrations exist. Many modern but in a lens corrected for longitudinal chromatic aberration refracting systems intended for use over an appreciable range the principal planes do not need to coincide for all colors. of wavelengths are ultimately limited in performance by Since the focal length is determined by the distance from the chromatic effects, both Gaussian and higher order. The his 30 rear principal plane to the image plane, the focal length may tory of astronomical telescope design provides a useful depend on the wavelength even when all images are in the example. Sir Isaac Newton invented the reflecting telescope same plane. FIG. 1C illustrates the origins of lateral chro because he considered that it was impossible to correct for the matic aberration. The size of the image varies from color to chromatic effects in singlet lenses by combining two to form color. The red image is magnified more than the green image, what we now call anachromatic doublet; in effect he thought 35 and both the red and green images are magnified more than that the chromatic effect of all lenses were proportional to their powers, with the same constant of proportionality even the blue image. for different glasses. Then, in the middle of the eighteenth In Summary, when a lens is corrected for longitudinal chro century, John Dollond and Chester Moore Hall showed that matic aberration, different colors focus more or less in the Newton had been wrong and they made achromatic doublets.
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