Abstract

For multi- and hyperspectral imagers, the integrity of the spectral information depends critically on the spatial coregistration between bands. There is at present no commonly accepted way to fully specify coregistration performance. This Letter shows how a relatively simple measurement technique can be used to form sharp images of the point spread function (PSF) in all bands, yielding information about spatial coregistration, as well as spatial resolution. A previously proposed metric is applied to characterize coregistration in terms of PSF similarity between bands. Resolution is characterized by ensquared energy. Two commercial hyperspectral cameras with nominally similar specifications are compared, and turn out to have large differences in their actual performance. The results, and the relative simplicity of the measurement, suggest that the method is suitable as a standardized performance test.

© 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

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References

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  1. K. Lenhard, A. Baumgartner, and T. Schwarzmaier, IEEE Trans. Geosci. Remote Sens. 53, 1828 (2015).
    [Crossref]
  2. L. B. Moore and P. Mouroulis, Proc. SPIE 10590, 105900Q (2017).
    [Crossref]
  3. J. Jemec, F. Pernuš, B. Likar, and M. Bürmen, Int. J. Comput. Vis. 121, 391 (2017).
    [Crossref]
  4. G. Høye, T. Løke, and A. Fridman, Opt. Eng. 54, 053102 (2015).
    [Crossref]
  5. T. Skauli, Opt. Express 20, 918 (2012).
    [Crossref]
  6. H. E. Torkildsen, H. Hovland, T. Opsahl, T. V. Haavardsholm, S. Nicolas, and T. Skauli, Proc. SPIE 9088, 908819 (2014).
    [Crossref]
  7. T. Skauli, Appl. Opt. 52, C58 (2013).
    [Crossref]
  8. H. Hovland, Opt. Express 17, 11371 (2009).
    [Crossref]
  9. T. Skauli, Proc. SPIE 10213, 102130H (2017).
    [Crossref]

2017 (3)

L. B. Moore and P. Mouroulis, Proc. SPIE 10590, 105900Q (2017).
[Crossref]

J. Jemec, F. Pernuš, B. Likar, and M. Bürmen, Int. J. Comput. Vis. 121, 391 (2017).
[Crossref]

T. Skauli, Proc. SPIE 10213, 102130H (2017).
[Crossref]

2015 (2)

K. Lenhard, A. Baumgartner, and T. Schwarzmaier, IEEE Trans. Geosci. Remote Sens. 53, 1828 (2015).
[Crossref]

G. Høye, T. Løke, and A. Fridman, Opt. Eng. 54, 053102 (2015).
[Crossref]

2014 (1)

H. E. Torkildsen, H. Hovland, T. Opsahl, T. V. Haavardsholm, S. Nicolas, and T. Skauli, Proc. SPIE 9088, 908819 (2014).
[Crossref]

2013 (1)

2012 (1)

2009 (1)

Baumgartner, A.

K. Lenhard, A. Baumgartner, and T. Schwarzmaier, IEEE Trans. Geosci. Remote Sens. 53, 1828 (2015).
[Crossref]

Bürmen, M.

J. Jemec, F. Pernuš, B. Likar, and M. Bürmen, Int. J. Comput. Vis. 121, 391 (2017).
[Crossref]

Fridman, A.

G. Høye, T. Løke, and A. Fridman, Opt. Eng. 54, 053102 (2015).
[Crossref]

Haavardsholm, T. V.

H. E. Torkildsen, H. Hovland, T. Opsahl, T. V. Haavardsholm, S. Nicolas, and T. Skauli, Proc. SPIE 9088, 908819 (2014).
[Crossref]

Hovland, H.

H. E. Torkildsen, H. Hovland, T. Opsahl, T. V. Haavardsholm, S. Nicolas, and T. Skauli, Proc. SPIE 9088, 908819 (2014).
[Crossref]

H. Hovland, Opt. Express 17, 11371 (2009).
[Crossref]

Høye, G.

G. Høye, T. Løke, and A. Fridman, Opt. Eng. 54, 053102 (2015).
[Crossref]

Jemec, J.

J. Jemec, F. Pernuš, B. Likar, and M. Bürmen, Int. J. Comput. Vis. 121, 391 (2017).
[Crossref]

Lenhard, K.

K. Lenhard, A. Baumgartner, and T. Schwarzmaier, IEEE Trans. Geosci. Remote Sens. 53, 1828 (2015).
[Crossref]

Likar, B.

J. Jemec, F. Pernuš, B. Likar, and M. Bürmen, Int. J. Comput. Vis. 121, 391 (2017).
[Crossref]

Løke, T.

G. Høye, T. Løke, and A. Fridman, Opt. Eng. 54, 053102 (2015).
[Crossref]

Moore, L. B.

L. B. Moore and P. Mouroulis, Proc. SPIE 10590, 105900Q (2017).
[Crossref]

Mouroulis, P.

L. B. Moore and P. Mouroulis, Proc. SPIE 10590, 105900Q (2017).
[Crossref]

Nicolas, S.

H. E. Torkildsen, H. Hovland, T. Opsahl, T. V. Haavardsholm, S. Nicolas, and T. Skauli, Proc. SPIE 9088, 908819 (2014).
[Crossref]

Opsahl, T.

H. E. Torkildsen, H. Hovland, T. Opsahl, T. V. Haavardsholm, S. Nicolas, and T. Skauli, Proc. SPIE 9088, 908819 (2014).
[Crossref]

Pernuš, F.

J. Jemec, F. Pernuš, B. Likar, and M. Bürmen, Int. J. Comput. Vis. 121, 391 (2017).
[Crossref]

Schwarzmaier, T.

K. Lenhard, A. Baumgartner, and T. Schwarzmaier, IEEE Trans. Geosci. Remote Sens. 53, 1828 (2015).
[Crossref]

Skauli, T.

T. Skauli, Proc. SPIE 10213, 102130H (2017).
[Crossref]

H. E. Torkildsen, H. Hovland, T. Opsahl, T. V. Haavardsholm, S. Nicolas, and T. Skauli, Proc. SPIE 9088, 908819 (2014).
[Crossref]

T. Skauli, Appl. Opt. 52, C58 (2013).
[Crossref]

T. Skauli, Opt. Express 20, 918 (2012).
[Crossref]

Torkildsen, H. E.

H. E. Torkildsen, H. Hovland, T. Opsahl, T. V. Haavardsholm, S. Nicolas, and T. Skauli, Proc. SPIE 9088, 908819 (2014).
[Crossref]

Appl. Opt. (1)

IEEE Trans. Geosci. Remote Sens. (1)

K. Lenhard, A. Baumgartner, and T. Schwarzmaier, IEEE Trans. Geosci. Remote Sens. 53, 1828 (2015).
[Crossref]

Int. J. Comput. Vis. (1)

J. Jemec, F. Pernuš, B. Likar, and M. Bürmen, Int. J. Comput. Vis. 121, 391 (2017).
[Crossref]

Opt. Eng. (1)

G. Høye, T. Løke, and A. Fridman, Opt. Eng. 54, 053102 (2015).
[Crossref]

Opt. Express (2)

Proc. SPIE (3)

L. B. Moore and P. Mouroulis, Proc. SPIE 10590, 105900Q (2017).
[Crossref]

H. E. Torkildsen, H. Hovland, T. Opsahl, T. V. Haavardsholm, S. Nicolas, and T. Skauli, Proc. SPIE 9088, 908819 (2014).
[Crossref]

T. Skauli, Proc. SPIE 10213, 102130H (2017).
[Crossref]

Supplementary Material (3)

NameDescription
» Visualization 1       Animation of the point spread function (PSF) variation with wavelength for a SpecIm PFD hyperspectral camera.
» Visualization 2       Animation of the point spread function (PSF) variation with wavelength for a HySpex VNIR-1800 hyperspectral camera.
» Visualization 3       Animation showing the spectra that would be recorded by different hyperspectral cameras for a scene consisting of an edge between black and white. The spectra are calculated from measured point spread functions (PSF).

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Figures (5)

Fig. 1.
Fig. 1. (a) Sketch of the measurement setup. A line source, formed by a slit, is scanned in different directions across part of the field of view. (b) Illustration of the slit scan pattern in the image plane. The slit scans across the PSF of the pixel under test, sequentially in a number of different directions, chosen according to the desired resolution.
Fig. 2.
Fig. 2. Example of a measured PSF, from the SpecIm camera at 699 nm wavelength. (a) Contour map of the PSF with coutours at 50%, 75%, and 90% enclosed energy. (b) and (c) Measured line spread function and cross section in the along (b) and across (c) track directions (red). Also shown are line spread functions calculated back from the reconstructed PSF (blue), as well as cross sections through the peak (black). (d) 3D plot of the PSF.
Fig. 3.
Fig. 3. Results from the SpecIm PFD camera. (a) Matrix ϵ s , n m of coregistration error between all band pairs. (b)–(d) Selected PSFs from pairs of wavelengths as shown. Contours enclose 50%, 75%, and 90% of PSF energy. The black rectangle is the specified pixel IFOV. (e) Wavelength dependence of “keystone” positional offset, calculated from PSF centroid in each band. See also Visualization 1.
Fig. 4.
Fig. 4. Results from the HySpex VNIR-1800 camera. (a) Matrix ϵ s , n m of coregistration error between all band pairs. Lower half: full resolution. Upper half: 3 × 3 binning for comparison (see text). (b)–(d) Selected PSF pairs, plotted as in Fig. 3. (e) Wavelength dependence of “keystone” positional offset, calculated from PSF centroid in each band. See also Visualization 2.
Fig. 5.
Fig. 5. Spectra that would be recorded near a black–white edge, calculated from the measured PSFs. Black lines: SpecIm camera. Blue: HySpex camera. Red: HySpex 3 × 3 binned pixel. Numbers indicate edge position relative to pixel center for the indicated groups of graphs. Insets show edges at position 2 pixels. (a) Edge oriented in the along-track direction, in different cross-track positions. (b) As in (a) with an edge in the cross-track direction. See Visualization 3.

Equations (1)

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ϵ s , n m = 1 2 x , y | f m ( x , y ) f n ( x , y ) | d x d y ,

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