Abstract

Wideband enhancement was implemented by detecting visually relevant edge and bar features in an image to produce a bipolar contour map. The addition of these contours to the original image resulted in increased local contrast of these features and an increase in the spatial bandwidth of the image. Testing with static television images revealed that visually impaired patients (n=35) could distinguish the enhanced images and preferred them over the original images (and degraded images). Most patients preferred a moderate level of wideband enhancement, since they preferred natural-looking images and rejected visible artifacts of the enhancement. Comparison of the enhanced images with the originals revealed that the improvement in the perceived image quality was significant for only 22% of the patients. Possible reasons for the limited increase in perceived image quality are discussed, and improvements are suggested.

© 2004 Optical Society of America

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. E. Peli, T. Peli, “Image enhancement for the visually impaired,” Opt. Eng. 23, 47–51 (1984).
    [CrossRef]
  2. E. Peli, “Head mounted display as a low vision aid,” in Proceedings of the Second International Conference on Virtual Reality and Persons with Disabilities (Center on Disabilities, California State University, Northridge, Calif., 1994), pp. 115–122.
  3. E. Peli, “Simple 1-D enhancement for head-mounted low vision aid,” Visual Impairment Res. 1, 3–10 (1999).
    [CrossRef]
  4. M. Berkowitz, L. G. Hiatt, P. de Toledo, J. Shapiro, M. Lurie, Characteristics, Activities and Needs of People with Limitation in Reading Print (American Foundation for the Blind, New York, 1979).
  5. E. Josephson, The Social Life of Blind People: a Leisure Activities Study, Research Series No. 19 (American Foundation for the Blind, New York, 1961).
  6. J. Packer, C. Kirchner, “Who’s watching? A profile of the blind and visually impaired audience for television and video” (American Foundation for the Blind, August25, 1997); retrieved 2003, http://www.afb.org/info_document_view.asp?documentid=1232 .
  7. B. J. Cronin, S. R. King, “The development of descriptive video service,” J. Visual Impairment Blindness, 503–506 (1990); http://www.afb.org/jvib_toc.asp .
  8. E. Peli, R. B. Goldstein, G. M. Young, C. L. Trempe, S. M. Buzney, “Image enhancement for the visually impaired: simulations and experimental results,” Invest. Ophthalmol. Visual Sci. 32, 2337–2350 (1991).
  9. R. G. Hier, G. W. Schmidt, R. S. Miller, S. E. DeForest, “Real-time locally adaptive contrast enhancement: a practical key to overcoming display and human-visual-system limitations,” in 1993 SID International Symposium Digest of Technical Papers, J. Morreale, ed. (Palisades Institute for Research Services, Inc., Seattle, Wash., 1993), pp. 491–494.
  10. E. Peli, E. M. Fine, K. Pisano, “Video enhancement of text and movies for the visually impaired,” in Low Vision: Research and New Developments in Rehabilitation, A. C. Kooijman, P. L. Looijestijn, J. A. Welling, G. J. van der Wildt, eds. (IOS Press, Amsterdam, 1994), pp. 191–198.
  11. E. Peli, E. Lee, C. L. Trempe, S. Buzney, “Image enhancement for the visually impaired: the effects of enhancement on face recognition,” J. Opt. Soc. Am. A 11, 1929–1939 (1994).
    [CrossRef]
  12. E. Fine, E. Peli, N. Brady, “Video enhancement improves performance of persons with moderate visual loss,” in Proceedings of the International Conference on Low Vision, “Vision 96” (Organización Nacional de Ciegos Españoles, Madrid, Spain, 1996), pp. 85–92.
  13. E. Peli, “Perceived quality of video enhanced for the visually impaired,” in Vision Science and Its Applications, Vol. 1 of 1999 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1999), pp. 46–48.
  14. J. Marchant, “Sampling theory of the human visual sense,” J. Opt. Soc. Am. 55, 1291–1296 (1965).
    [CrossRef]
  15. E. Peli, J. Yang, R. B. Goldstein, “Image invariance with changes in size: the role of peripheral contrast thresholds,” J. Opt. Soc. Am. A 8, 1762–1774 (1991).
    [CrossRef] [PubMed]
  16. V. Virsu, R. Nasanen, K. Osmoviita, “The cortical magnification and peripheral vision,” J. Opt. Soc. Am. A 4, 1568–1578 (1987).
    [CrossRef] [PubMed]
  17. G. Westheimer, “The spatial grain of the perifoveal visual field,” Vision Res. 22, 157–162 (1982).
    [CrossRef] [PubMed]
  18. J. Millodot, C. A. Johnson, A. Lamont, H. W. Leibowitz, “Effects of dioptrics on peripheral acuity,” Vision Res. 15, 1357–1362 (1975).
    [CrossRef] [PubMed]
  19. H. Strasburger, L. O. Harvey, I. Rentschler, “Contrast thresholds for identification of numeric characters in direct and eccentric view,” Percept. Psychophys. 49, 495–508 (1991).
    [CrossRef] [PubMed]
  20. H. Strasburger, I. Rentschler, J. L. O. Harvey, “Cortical magnification theory fails to predict visual recognition,” Eur. J. Neurosci. 6, 1583–1587 (1994).
    [CrossRef] [PubMed]
  21. P. Mäkelä, R. Näsänen, J. Rovamo, D. Melmoth, “Identification of facial images in peripheral vision,” Vision Res. 41, 599–610 (2001).
    [CrossRef] [PubMed]
  22. P. J. Bennett, M. S. Banks, “Sensitivity loss in odd-symmetric mechanisms and phase anomalies in peripheral vision,” Nature 326, 873–876 (1987).
    [CrossRef] [PubMed]
  23. P. J. Bennett, M. S. Banks, “The effects of contrast, spatial scale, and orientation on foveal and peripheral phase discrimination,” Vision Res. 31, 1759–1786 (1991).
    [CrossRef] [PubMed]
  24. C. M. E. Stephenson, A. J. Knapp, O. J. Braddick, “Discrimination of spatial phase shows a qualitative difference between foveal and peripheral processing,” Vision Res. 31, 11315–11326 (1991).
    [CrossRef]
  25. M. C. Morrone, D. C. Burr, “Discrimination of spatial phase in central and peripheral vision,” Vision Res. 29, 433–445 (1989).
    [CrossRef] [PubMed]
  26. R. F. Hess, A. Hayes, “The coding of spatial position by the human visual system: effects of spatial scale and retinal eccentricity,” Vision Res. 34, 625–643 (1994).
    [CrossRef] [PubMed]
  27. A. Toet, J. J. Koendrink, “Effects of blur and eccentricity on differential displacement discrimination,” Vision Res. 28, 535–553 (1988).
    [CrossRef]
  28. E. Peli, “Wideband image enhancement for the visually impaired (abstract),” Invest. Ophthalmol. Visual Sci. Suppl. 39, s398 (1998).
  29. M. A. Georgeson, T. C. A. Freeman, “Perceived location of bars and edges in one dimensional images: computational models and human vision,” Vision Res. 37, 127–142 (1997).
    [CrossRef] [PubMed]
  30. E. Peli, “Feature detection algorithm based on a visual system model,” Proc. IEEE 90, 78–93 (2002).
    [CrossRef]
  31. E. Peli, “Wideband image enhancement,” U.S. patent6,611,618 (August26, 2003).
  32. Blurred images were used (1) to prevent “floor” effects, (2) to determine whether degraded images were visible to low-vision patients, and (3) to test the validity of our psychophysical methods.
  33. The graphics tablet collected continuous values, but there were large words on the tablet indicating a rating scale to the patient.
  34. M. Ardito, “Preferred viewing distance and display parameters,” in MOSAIC Handbook (O’Reilly, Sebastopol, Calif., 1996), pp. 165–181.
  35. J. Freund, B. Perles, “A new look at quartiles of ungrouped data,” Am. Stat. 41, 200–203 (1987).
  36. N. A. Macmillan, C. D. Creelman, Detection Theory: A User’s Guide (Cambridge U. Press, Cambridge, UK, 1991).
  37. C. E. Metz, P. Wang, H. B. Kronman, “A new approach for testing the significance of differences between ROC curves measured from correlated data,” in Proceedings of VIII Conference on Information Processing in Medical Imaging (Nijhoff, The Hague, 1984), pp. 432–445.
  38. J. A. Hanley, B. J. McNeil, “The meaning and use of the area under a receiver operating characteristic (ROC) curve,” Radiology 143, 29–36 (1982).
    [PubMed]
  39. R. Barbeito, T. L. Simpson, “Should level of measurement considerations affect the choice of statistic?” Optom. Vision Sci. 68, 236–242 (1991).
    [CrossRef]
  40. J. M. Bland, D. G. Altman, “Statistical methods for assessing agreement between two methods of clinical measurement,” Lancet (8476) 1, 307–310 (1986).
    [CrossRef] [PubMed]
  41. E. Peli, “Test of a model of foveal vision by using simulations,” J. Opt. Soc. Am. A 13, 1131–1138 (1996).
    [CrossRef]
  42. E. Peli, G. Young, E. Lee, C. Trempe, “Effects of distortions due to image enhancement on face recognition,” in Noninvasive Assessment of the Visual System, Vol. 1 of 1992 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1992), pp. 18–21.
  43. E. Peli, “Limitations of image enhancement for the visually impaired,” Optom. Vision Sci. 69, 15–24 (1992).
    [CrossRef]
  44. M. A. Webster, M. A. Georgeson, S. M. Webster, “Neural adjustments to image blur,” Nat. Neurosci. 5, 839–840 (2002).
    [CrossRef] [PubMed]
  45. E. Peli, “Display nonlinearity in digital image processing for visual communications,” Opt. Eng. 31, 2374–2382 (1992).
    [CrossRef]
  46. R. C. Gonzalez, R. E. Woods, Digital Image Processing (Addison-Wesley, Reading, Mass., 1992).
  47. J. Russ, The Image Processing Handbook, 2nd ed. (CRC Press, Boca Raton, Fla., 1995), p. 674.

2002 (2)

E. Peli, “Feature detection algorithm based on a visual system model,” Proc. IEEE 90, 78–93 (2002).
[CrossRef]

M. A. Webster, M. A. Georgeson, S. M. Webster, “Neural adjustments to image blur,” Nat. Neurosci. 5, 839–840 (2002).
[CrossRef] [PubMed]

2001 (1)

P. Mäkelä, R. Näsänen, J. Rovamo, D. Melmoth, “Identification of facial images in peripheral vision,” Vision Res. 41, 599–610 (2001).
[CrossRef] [PubMed]

1999 (1)

E. Peli, “Simple 1-D enhancement for head-mounted low vision aid,” Visual Impairment Res. 1, 3–10 (1999).
[CrossRef]

1998 (1)

E. Peli, “Wideband image enhancement for the visually impaired (abstract),” Invest. Ophthalmol. Visual Sci. Suppl. 39, s398 (1998).

1997 (1)

M. A. Georgeson, T. C. A. Freeman, “Perceived location of bars and edges in one dimensional images: computational models and human vision,” Vision Res. 37, 127–142 (1997).
[CrossRef] [PubMed]

1996 (1)

1994 (3)

E. Peli, E. Lee, C. L. Trempe, S. Buzney, “Image enhancement for the visually impaired: the effects of enhancement on face recognition,” J. Opt. Soc. Am. A 11, 1929–1939 (1994).
[CrossRef]

R. F. Hess, A. Hayes, “The coding of spatial position by the human visual system: effects of spatial scale and retinal eccentricity,” Vision Res. 34, 625–643 (1994).
[CrossRef] [PubMed]

H. Strasburger, I. Rentschler, J. L. O. Harvey, “Cortical magnification theory fails to predict visual recognition,” Eur. J. Neurosci. 6, 1583–1587 (1994).
[CrossRef] [PubMed]

1992 (2)

E. Peli, “Display nonlinearity in digital image processing for visual communications,” Opt. Eng. 31, 2374–2382 (1992).
[CrossRef]

E. Peli, “Limitations of image enhancement for the visually impaired,” Optom. Vision Sci. 69, 15–24 (1992).
[CrossRef]

1991 (6)

E. Peli, R. B. Goldstein, G. M. Young, C. L. Trempe, S. M. Buzney, “Image enhancement for the visually impaired: simulations and experimental results,” Invest. Ophthalmol. Visual Sci. 32, 2337–2350 (1991).

E. Peli, J. Yang, R. B. Goldstein, “Image invariance with changes in size: the role of peripheral contrast thresholds,” J. Opt. Soc. Am. A 8, 1762–1774 (1991).
[CrossRef] [PubMed]

H. Strasburger, L. O. Harvey, I. Rentschler, “Contrast thresholds for identification of numeric characters in direct and eccentric view,” Percept. Psychophys. 49, 495–508 (1991).
[CrossRef] [PubMed]

P. J. Bennett, M. S. Banks, “The effects of contrast, spatial scale, and orientation on foveal and peripheral phase discrimination,” Vision Res. 31, 1759–1786 (1991).
[CrossRef] [PubMed]

C. M. E. Stephenson, A. J. Knapp, O. J. Braddick, “Discrimination of spatial phase shows a qualitative difference between foveal and peripheral processing,” Vision Res. 31, 11315–11326 (1991).
[CrossRef]

R. Barbeito, T. L. Simpson, “Should level of measurement considerations affect the choice of statistic?” Optom. Vision Sci. 68, 236–242 (1991).
[CrossRef]

1990 (1)

B. J. Cronin, S. R. King, “The development of descriptive video service,” J. Visual Impairment Blindness, 503–506 (1990); http://www.afb.org/jvib_toc.asp .

1989 (1)

M. C. Morrone, D. C. Burr, “Discrimination of spatial phase in central and peripheral vision,” Vision Res. 29, 433–445 (1989).
[CrossRef] [PubMed]

1988 (1)

A. Toet, J. J. Koendrink, “Effects of blur and eccentricity on differential displacement discrimination,” Vision Res. 28, 535–553 (1988).
[CrossRef]

1987 (3)

J. Freund, B. Perles, “A new look at quartiles of ungrouped data,” Am. Stat. 41, 200–203 (1987).

P. J. Bennett, M. S. Banks, “Sensitivity loss in odd-symmetric mechanisms and phase anomalies in peripheral vision,” Nature 326, 873–876 (1987).
[CrossRef] [PubMed]

V. Virsu, R. Nasanen, K. Osmoviita, “The cortical magnification and peripheral vision,” J. Opt. Soc. Am. A 4, 1568–1578 (1987).
[CrossRef] [PubMed]

1986 (1)

J. M. Bland, D. G. Altman, “Statistical methods for assessing agreement between two methods of clinical measurement,” Lancet (8476) 1, 307–310 (1986).
[CrossRef] [PubMed]

1984 (1)

E. Peli, T. Peli, “Image enhancement for the visually impaired,” Opt. Eng. 23, 47–51 (1984).
[CrossRef]

1982 (2)

J. A. Hanley, B. J. McNeil, “The meaning and use of the area under a receiver operating characteristic (ROC) curve,” Radiology 143, 29–36 (1982).
[PubMed]

G. Westheimer, “The spatial grain of the perifoveal visual field,” Vision Res. 22, 157–162 (1982).
[CrossRef] [PubMed]

1975 (1)

J. Millodot, C. A. Johnson, A. Lamont, H. W. Leibowitz, “Effects of dioptrics on peripheral acuity,” Vision Res. 15, 1357–1362 (1975).
[CrossRef] [PubMed]

1965 (1)

Altman, D. G.

J. M. Bland, D. G. Altman, “Statistical methods for assessing agreement between two methods of clinical measurement,” Lancet (8476) 1, 307–310 (1986).
[CrossRef] [PubMed]

Ardito, M.

M. Ardito, “Preferred viewing distance and display parameters,” in MOSAIC Handbook (O’Reilly, Sebastopol, Calif., 1996), pp. 165–181.

Banks, M. S.

P. J. Bennett, M. S. Banks, “The effects of contrast, spatial scale, and orientation on foveal and peripheral phase discrimination,” Vision Res. 31, 1759–1786 (1991).
[CrossRef] [PubMed]

P. J. Bennett, M. S. Banks, “Sensitivity loss in odd-symmetric mechanisms and phase anomalies in peripheral vision,” Nature 326, 873–876 (1987).
[CrossRef] [PubMed]

Barbeito, R.

R. Barbeito, T. L. Simpson, “Should level of measurement considerations affect the choice of statistic?” Optom. Vision Sci. 68, 236–242 (1991).
[CrossRef]

Bennett, P. J.

P. J. Bennett, M. S. Banks, “The effects of contrast, spatial scale, and orientation on foveal and peripheral phase discrimination,” Vision Res. 31, 1759–1786 (1991).
[CrossRef] [PubMed]

P. J. Bennett, M. S. Banks, “Sensitivity loss in odd-symmetric mechanisms and phase anomalies in peripheral vision,” Nature 326, 873–876 (1987).
[CrossRef] [PubMed]

Berkowitz, M.

M. Berkowitz, L. G. Hiatt, P. de Toledo, J. Shapiro, M. Lurie, Characteristics, Activities and Needs of People with Limitation in Reading Print (American Foundation for the Blind, New York, 1979).

Bland, J. M.

J. M. Bland, D. G. Altman, “Statistical methods for assessing agreement between two methods of clinical measurement,” Lancet (8476) 1, 307–310 (1986).
[CrossRef] [PubMed]

Braddick, O. J.

C. M. E. Stephenson, A. J. Knapp, O. J. Braddick, “Discrimination of spatial phase shows a qualitative difference between foveal and peripheral processing,” Vision Res. 31, 11315–11326 (1991).
[CrossRef]

Brady, N.

E. Fine, E. Peli, N. Brady, “Video enhancement improves performance of persons with moderate visual loss,” in Proceedings of the International Conference on Low Vision, “Vision 96” (Organización Nacional de Ciegos Españoles, Madrid, Spain, 1996), pp. 85–92.

Burr, D. C.

M. C. Morrone, D. C. Burr, “Discrimination of spatial phase in central and peripheral vision,” Vision Res. 29, 433–445 (1989).
[CrossRef] [PubMed]

Buzney, S.

Buzney, S. M.

E. Peli, R. B. Goldstein, G. M. Young, C. L. Trempe, S. M. Buzney, “Image enhancement for the visually impaired: simulations and experimental results,” Invest. Ophthalmol. Visual Sci. 32, 2337–2350 (1991).

Creelman, C. D.

N. A. Macmillan, C. D. Creelman, Detection Theory: A User’s Guide (Cambridge U. Press, Cambridge, UK, 1991).

Cronin, B. J.

B. J. Cronin, S. R. King, “The development of descriptive video service,” J. Visual Impairment Blindness, 503–506 (1990); http://www.afb.org/jvib_toc.asp .

de Toledo, P.

M. Berkowitz, L. G. Hiatt, P. de Toledo, J. Shapiro, M. Lurie, Characteristics, Activities and Needs of People with Limitation in Reading Print (American Foundation for the Blind, New York, 1979).

DeForest, S. E.

R. G. Hier, G. W. Schmidt, R. S. Miller, S. E. DeForest, “Real-time locally adaptive contrast enhancement: a practical key to overcoming display and human-visual-system limitations,” in 1993 SID International Symposium Digest of Technical Papers, J. Morreale, ed. (Palisades Institute for Research Services, Inc., Seattle, Wash., 1993), pp. 491–494.

Fine, E.

E. Fine, E. Peli, N. Brady, “Video enhancement improves performance of persons with moderate visual loss,” in Proceedings of the International Conference on Low Vision, “Vision 96” (Organización Nacional de Ciegos Españoles, Madrid, Spain, 1996), pp. 85–92.

Fine, E. M.

E. Peli, E. M. Fine, K. Pisano, “Video enhancement of text and movies for the visually impaired,” in Low Vision: Research and New Developments in Rehabilitation, A. C. Kooijman, P. L. Looijestijn, J. A. Welling, G. J. van der Wildt, eds. (IOS Press, Amsterdam, 1994), pp. 191–198.

Freeman, T. C. A.

M. A. Georgeson, T. C. A. Freeman, “Perceived location of bars and edges in one dimensional images: computational models and human vision,” Vision Res. 37, 127–142 (1997).
[CrossRef] [PubMed]

Freund, J.

J. Freund, B. Perles, “A new look at quartiles of ungrouped data,” Am. Stat. 41, 200–203 (1987).

Georgeson, M. A.

M. A. Webster, M. A. Georgeson, S. M. Webster, “Neural adjustments to image blur,” Nat. Neurosci. 5, 839–840 (2002).
[CrossRef] [PubMed]

M. A. Georgeson, T. C. A. Freeman, “Perceived location of bars and edges in one dimensional images: computational models and human vision,” Vision Res. 37, 127–142 (1997).
[CrossRef] [PubMed]

Goldstein, R. B.

E. Peli, R. B. Goldstein, G. M. Young, C. L. Trempe, S. M. Buzney, “Image enhancement for the visually impaired: simulations and experimental results,” Invest. Ophthalmol. Visual Sci. 32, 2337–2350 (1991).

E. Peli, J. Yang, R. B. Goldstein, “Image invariance with changes in size: the role of peripheral contrast thresholds,” J. Opt. Soc. Am. A 8, 1762–1774 (1991).
[CrossRef] [PubMed]

Gonzalez, R. C.

R. C. Gonzalez, R. E. Woods, Digital Image Processing (Addison-Wesley, Reading, Mass., 1992).

Hanley, J. A.

J. A. Hanley, B. J. McNeil, “The meaning and use of the area under a receiver operating characteristic (ROC) curve,” Radiology 143, 29–36 (1982).
[PubMed]

Harvey, J. L. O.

H. Strasburger, I. Rentschler, J. L. O. Harvey, “Cortical magnification theory fails to predict visual recognition,” Eur. J. Neurosci. 6, 1583–1587 (1994).
[CrossRef] [PubMed]

Harvey, L. O.

H. Strasburger, L. O. Harvey, I. Rentschler, “Contrast thresholds for identification of numeric characters in direct and eccentric view,” Percept. Psychophys. 49, 495–508 (1991).
[CrossRef] [PubMed]

Hayes, A.

R. F. Hess, A. Hayes, “The coding of spatial position by the human visual system: effects of spatial scale and retinal eccentricity,” Vision Res. 34, 625–643 (1994).
[CrossRef] [PubMed]

Hess, R. F.

R. F. Hess, A. Hayes, “The coding of spatial position by the human visual system: effects of spatial scale and retinal eccentricity,” Vision Res. 34, 625–643 (1994).
[CrossRef] [PubMed]

Hiatt, L. G.

M. Berkowitz, L. G. Hiatt, P. de Toledo, J. Shapiro, M. Lurie, Characteristics, Activities and Needs of People with Limitation in Reading Print (American Foundation for the Blind, New York, 1979).

Hier, R. G.

R. G. Hier, G. W. Schmidt, R. S. Miller, S. E. DeForest, “Real-time locally adaptive contrast enhancement: a practical key to overcoming display and human-visual-system limitations,” in 1993 SID International Symposium Digest of Technical Papers, J. Morreale, ed. (Palisades Institute for Research Services, Inc., Seattle, Wash., 1993), pp. 491–494.

Johnson, C. A.

J. Millodot, C. A. Johnson, A. Lamont, H. W. Leibowitz, “Effects of dioptrics on peripheral acuity,” Vision Res. 15, 1357–1362 (1975).
[CrossRef] [PubMed]

Josephson, E.

E. Josephson, The Social Life of Blind People: a Leisure Activities Study, Research Series No. 19 (American Foundation for the Blind, New York, 1961).

King, S. R.

B. J. Cronin, S. R. King, “The development of descriptive video service,” J. Visual Impairment Blindness, 503–506 (1990); http://www.afb.org/jvib_toc.asp .

Kirchner, C.

J. Packer, C. Kirchner, “Who’s watching? A profile of the blind and visually impaired audience for television and video” (American Foundation for the Blind, August25, 1997); retrieved 2003, http://www.afb.org/info_document_view.asp?documentid=1232 .

Knapp, A. J.

C. M. E. Stephenson, A. J. Knapp, O. J. Braddick, “Discrimination of spatial phase shows a qualitative difference between foveal and peripheral processing,” Vision Res. 31, 11315–11326 (1991).
[CrossRef]

Koendrink, J. J.

A. Toet, J. J. Koendrink, “Effects of blur and eccentricity on differential displacement discrimination,” Vision Res. 28, 535–553 (1988).
[CrossRef]

Kronman, H. B.

C. E. Metz, P. Wang, H. B. Kronman, “A new approach for testing the significance of differences between ROC curves measured from correlated data,” in Proceedings of VIII Conference on Information Processing in Medical Imaging (Nijhoff, The Hague, 1984), pp. 432–445.

Lamont, A.

J. Millodot, C. A. Johnson, A. Lamont, H. W. Leibowitz, “Effects of dioptrics on peripheral acuity,” Vision Res. 15, 1357–1362 (1975).
[CrossRef] [PubMed]

Lee, E.

E. Peli, E. Lee, C. L. Trempe, S. Buzney, “Image enhancement for the visually impaired: the effects of enhancement on face recognition,” J. Opt. Soc. Am. A 11, 1929–1939 (1994).
[CrossRef]

E. Peli, G. Young, E. Lee, C. Trempe, “Effects of distortions due to image enhancement on face recognition,” in Noninvasive Assessment of the Visual System, Vol. 1 of 1992 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1992), pp. 18–21.

Leibowitz, H. W.

J. Millodot, C. A. Johnson, A. Lamont, H. W. Leibowitz, “Effects of dioptrics on peripheral acuity,” Vision Res. 15, 1357–1362 (1975).
[CrossRef] [PubMed]

Lurie, M.

M. Berkowitz, L. G. Hiatt, P. de Toledo, J. Shapiro, M. Lurie, Characteristics, Activities and Needs of People with Limitation in Reading Print (American Foundation for the Blind, New York, 1979).

Macmillan, N. A.

N. A. Macmillan, C. D. Creelman, Detection Theory: A User’s Guide (Cambridge U. Press, Cambridge, UK, 1991).

Mäkelä, P.

P. Mäkelä, R. Näsänen, J. Rovamo, D. Melmoth, “Identification of facial images in peripheral vision,” Vision Res. 41, 599–610 (2001).
[CrossRef] [PubMed]

Marchant, J.

McNeil, B. J.

J. A. Hanley, B. J. McNeil, “The meaning and use of the area under a receiver operating characteristic (ROC) curve,” Radiology 143, 29–36 (1982).
[PubMed]

Melmoth, D.

P. Mäkelä, R. Näsänen, J. Rovamo, D. Melmoth, “Identification of facial images in peripheral vision,” Vision Res. 41, 599–610 (2001).
[CrossRef] [PubMed]

Metz, C. E.

C. E. Metz, P. Wang, H. B. Kronman, “A new approach for testing the significance of differences between ROC curves measured from correlated data,” in Proceedings of VIII Conference on Information Processing in Medical Imaging (Nijhoff, The Hague, 1984), pp. 432–445.

Miller, R. S.

R. G. Hier, G. W. Schmidt, R. S. Miller, S. E. DeForest, “Real-time locally adaptive contrast enhancement: a practical key to overcoming display and human-visual-system limitations,” in 1993 SID International Symposium Digest of Technical Papers, J. Morreale, ed. (Palisades Institute for Research Services, Inc., Seattle, Wash., 1993), pp. 491–494.

Millodot, J.

J. Millodot, C. A. Johnson, A. Lamont, H. W. Leibowitz, “Effects of dioptrics on peripheral acuity,” Vision Res. 15, 1357–1362 (1975).
[CrossRef] [PubMed]

Morrone, M. C.

M. C. Morrone, D. C. Burr, “Discrimination of spatial phase in central and peripheral vision,” Vision Res. 29, 433–445 (1989).
[CrossRef] [PubMed]

Nasanen, R.

Näsänen, R.

P. Mäkelä, R. Näsänen, J. Rovamo, D. Melmoth, “Identification of facial images in peripheral vision,” Vision Res. 41, 599–610 (2001).
[CrossRef] [PubMed]

Osmoviita, K.

Packer, J.

J. Packer, C. Kirchner, “Who’s watching? A profile of the blind and visually impaired audience for television and video” (American Foundation for the Blind, August25, 1997); retrieved 2003, http://www.afb.org/info_document_view.asp?documentid=1232 .

Peli, E.

E. Peli, “Feature detection algorithm based on a visual system model,” Proc. IEEE 90, 78–93 (2002).
[CrossRef]

E. Peli, “Simple 1-D enhancement for head-mounted low vision aid,” Visual Impairment Res. 1, 3–10 (1999).
[CrossRef]

E. Peli, “Wideband image enhancement for the visually impaired (abstract),” Invest. Ophthalmol. Visual Sci. Suppl. 39, s398 (1998).

E. Peli, “Test of a model of foveal vision by using simulations,” J. Opt. Soc. Am. A 13, 1131–1138 (1996).
[CrossRef]

E. Peli, E. Lee, C. L. Trempe, S. Buzney, “Image enhancement for the visually impaired: the effects of enhancement on face recognition,” J. Opt. Soc. Am. A 11, 1929–1939 (1994).
[CrossRef]

E. Peli, “Limitations of image enhancement for the visually impaired,” Optom. Vision Sci. 69, 15–24 (1992).
[CrossRef]

E. Peli, “Display nonlinearity in digital image processing for visual communications,” Opt. Eng. 31, 2374–2382 (1992).
[CrossRef]

E. Peli, J. Yang, R. B. Goldstein, “Image invariance with changes in size: the role of peripheral contrast thresholds,” J. Opt. Soc. Am. A 8, 1762–1774 (1991).
[CrossRef] [PubMed]

E. Peli, R. B. Goldstein, G. M. Young, C. L. Trempe, S. M. Buzney, “Image enhancement for the visually impaired: simulations and experimental results,” Invest. Ophthalmol. Visual Sci. 32, 2337–2350 (1991).

E. Peli, T. Peli, “Image enhancement for the visually impaired,” Opt. Eng. 23, 47–51 (1984).
[CrossRef]

E. Fine, E. Peli, N. Brady, “Video enhancement improves performance of persons with moderate visual loss,” in Proceedings of the International Conference on Low Vision, “Vision 96” (Organización Nacional de Ciegos Españoles, Madrid, Spain, 1996), pp. 85–92.

E. Peli, “Head mounted display as a low vision aid,” in Proceedings of the Second International Conference on Virtual Reality and Persons with Disabilities (Center on Disabilities, California State University, Northridge, Calif., 1994), pp. 115–122.

E. Peli, “Perceived quality of video enhanced for the visually impaired,” in Vision Science and Its Applications, Vol. 1 of 1999 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1999), pp. 46–48.

E. Peli, “Wideband image enhancement,” U.S. patent6,611,618 (August26, 2003).

E. Peli, G. Young, E. Lee, C. Trempe, “Effects of distortions due to image enhancement on face recognition,” in Noninvasive Assessment of the Visual System, Vol. 1 of 1992 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1992), pp. 18–21.

E. Peli, E. M. Fine, K. Pisano, “Video enhancement of text and movies for the visually impaired,” in Low Vision: Research and New Developments in Rehabilitation, A. C. Kooijman, P. L. Looijestijn, J. A. Welling, G. J. van der Wildt, eds. (IOS Press, Amsterdam, 1994), pp. 191–198.

Peli, T.

E. Peli, T. Peli, “Image enhancement for the visually impaired,” Opt. Eng. 23, 47–51 (1984).
[CrossRef]

Perles, B.

J. Freund, B. Perles, “A new look at quartiles of ungrouped data,” Am. Stat. 41, 200–203 (1987).

Pisano, K.

E. Peli, E. M. Fine, K. Pisano, “Video enhancement of text and movies for the visually impaired,” in Low Vision: Research and New Developments in Rehabilitation, A. C. Kooijman, P. L. Looijestijn, J. A. Welling, G. J. van der Wildt, eds. (IOS Press, Amsterdam, 1994), pp. 191–198.

Rentschler, I.

H. Strasburger, I. Rentschler, J. L. O. Harvey, “Cortical magnification theory fails to predict visual recognition,” Eur. J. Neurosci. 6, 1583–1587 (1994).
[CrossRef] [PubMed]

H. Strasburger, L. O. Harvey, I. Rentschler, “Contrast thresholds for identification of numeric characters in direct and eccentric view,” Percept. Psychophys. 49, 495–508 (1991).
[CrossRef] [PubMed]

Rovamo, J.

P. Mäkelä, R. Näsänen, J. Rovamo, D. Melmoth, “Identification of facial images in peripheral vision,” Vision Res. 41, 599–610 (2001).
[CrossRef] [PubMed]

Russ, J.

J. Russ, The Image Processing Handbook, 2nd ed. (CRC Press, Boca Raton, Fla., 1995), p. 674.

Schmidt, G. W.

R. G. Hier, G. W. Schmidt, R. S. Miller, S. E. DeForest, “Real-time locally adaptive contrast enhancement: a practical key to overcoming display and human-visual-system limitations,” in 1993 SID International Symposium Digest of Technical Papers, J. Morreale, ed. (Palisades Institute for Research Services, Inc., Seattle, Wash., 1993), pp. 491–494.

Shapiro, J.

M. Berkowitz, L. G. Hiatt, P. de Toledo, J. Shapiro, M. Lurie, Characteristics, Activities and Needs of People with Limitation in Reading Print (American Foundation for the Blind, New York, 1979).

Simpson, T. L.

R. Barbeito, T. L. Simpson, “Should level of measurement considerations affect the choice of statistic?” Optom. Vision Sci. 68, 236–242 (1991).
[CrossRef]

Stephenson, C. M. E.

C. M. E. Stephenson, A. J. Knapp, O. J. Braddick, “Discrimination of spatial phase shows a qualitative difference between foveal and peripheral processing,” Vision Res. 31, 11315–11326 (1991).
[CrossRef]

Strasburger, H.

H. Strasburger, I. Rentschler, J. L. O. Harvey, “Cortical magnification theory fails to predict visual recognition,” Eur. J. Neurosci. 6, 1583–1587 (1994).
[CrossRef] [PubMed]

H. Strasburger, L. O. Harvey, I. Rentschler, “Contrast thresholds for identification of numeric characters in direct and eccentric view,” Percept. Psychophys. 49, 495–508 (1991).
[CrossRef] [PubMed]

Toet, A.

A. Toet, J. J. Koendrink, “Effects of blur and eccentricity on differential displacement discrimination,” Vision Res. 28, 535–553 (1988).
[CrossRef]

Trempe, C.

E. Peli, G. Young, E. Lee, C. Trempe, “Effects of distortions due to image enhancement on face recognition,” in Noninvasive Assessment of the Visual System, Vol. 1 of 1992 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1992), pp. 18–21.

Trempe, C. L.

E. Peli, E. Lee, C. L. Trempe, S. Buzney, “Image enhancement for the visually impaired: the effects of enhancement on face recognition,” J. Opt. Soc. Am. A 11, 1929–1939 (1994).
[CrossRef]

E. Peli, R. B. Goldstein, G. M. Young, C. L. Trempe, S. M. Buzney, “Image enhancement for the visually impaired: simulations and experimental results,” Invest. Ophthalmol. Visual Sci. 32, 2337–2350 (1991).

Virsu, V.

Wang, P.

C. E. Metz, P. Wang, H. B. Kronman, “A new approach for testing the significance of differences between ROC curves measured from correlated data,” in Proceedings of VIII Conference on Information Processing in Medical Imaging (Nijhoff, The Hague, 1984), pp. 432–445.

Webster, M. A.

M. A. Webster, M. A. Georgeson, S. M. Webster, “Neural adjustments to image blur,” Nat. Neurosci. 5, 839–840 (2002).
[CrossRef] [PubMed]

Webster, S. M.

M. A. Webster, M. A. Georgeson, S. M. Webster, “Neural adjustments to image blur,” Nat. Neurosci. 5, 839–840 (2002).
[CrossRef] [PubMed]

Westheimer, G.

G. Westheimer, “The spatial grain of the perifoveal visual field,” Vision Res. 22, 157–162 (1982).
[CrossRef] [PubMed]

Woods, R. E.

R. C. Gonzalez, R. E. Woods, Digital Image Processing (Addison-Wesley, Reading, Mass., 1992).

Yang, J.

Young, G.

E. Peli, G. Young, E. Lee, C. Trempe, “Effects of distortions due to image enhancement on face recognition,” in Noninvasive Assessment of the Visual System, Vol. 1 of 1992 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1992), pp. 18–21.

Young, G. M.

E. Peli, R. B. Goldstein, G. M. Young, C. L. Trempe, S. M. Buzney, “Image enhancement for the visually impaired: simulations and experimental results,” Invest. Ophthalmol. Visual Sci. 32, 2337–2350 (1991).

Am. Stat. (1)

J. Freund, B. Perles, “A new look at quartiles of ungrouped data,” Am. Stat. 41, 200–203 (1987).

Eur. J. Neurosci. (1)

H. Strasburger, I. Rentschler, J. L. O. Harvey, “Cortical magnification theory fails to predict visual recognition,” Eur. J. Neurosci. 6, 1583–1587 (1994).
[CrossRef] [PubMed]

Invest. Ophthalmol. Visual Sci. (1)

E. Peli, R. B. Goldstein, G. M. Young, C. L. Trempe, S. M. Buzney, “Image enhancement for the visually impaired: simulations and experimental results,” Invest. Ophthalmol. Visual Sci. 32, 2337–2350 (1991).

Invest. Ophthalmol. Visual Sci. Suppl. (1)

E. Peli, “Wideband image enhancement for the visually impaired (abstract),” Invest. Ophthalmol. Visual Sci. Suppl. 39, s398 (1998).

J. Opt. Soc. Am. (1)

J. Opt. Soc. Am. A (4)

J. Visual Impairment Blindness (1)

B. J. Cronin, S. R. King, “The development of descriptive video service,” J. Visual Impairment Blindness, 503–506 (1990); http://www.afb.org/jvib_toc.asp .

Lancet (8476) (1)

J. M. Bland, D. G. Altman, “Statistical methods for assessing agreement between two methods of clinical measurement,” Lancet (8476) 1, 307–310 (1986).
[CrossRef] [PubMed]

Nat. Neurosci. (1)

M. A. Webster, M. A. Georgeson, S. M. Webster, “Neural adjustments to image blur,” Nat. Neurosci. 5, 839–840 (2002).
[CrossRef] [PubMed]

Nature (1)

P. J. Bennett, M. S. Banks, “Sensitivity loss in odd-symmetric mechanisms and phase anomalies in peripheral vision,” Nature 326, 873–876 (1987).
[CrossRef] [PubMed]

Opt. Eng. (2)

E. Peli, “Display nonlinearity in digital image processing for visual communications,” Opt. Eng. 31, 2374–2382 (1992).
[CrossRef]

E. Peli, T. Peli, “Image enhancement for the visually impaired,” Opt. Eng. 23, 47–51 (1984).
[CrossRef]

Optom. Vision Sci. (2)

R. Barbeito, T. L. Simpson, “Should level of measurement considerations affect the choice of statistic?” Optom. Vision Sci. 68, 236–242 (1991).
[CrossRef]

E. Peli, “Limitations of image enhancement for the visually impaired,” Optom. Vision Sci. 69, 15–24 (1992).
[CrossRef]

Percept. Psychophys. (1)

H. Strasburger, L. O. Harvey, I. Rentschler, “Contrast thresholds for identification of numeric characters in direct and eccentric view,” Percept. Psychophys. 49, 495–508 (1991).
[CrossRef] [PubMed]

Proc. IEEE (1)

E. Peli, “Feature detection algorithm based on a visual system model,” Proc. IEEE 90, 78–93 (2002).
[CrossRef]

Radiology (1)

J. A. Hanley, B. J. McNeil, “The meaning and use of the area under a receiver operating characteristic (ROC) curve,” Radiology 143, 29–36 (1982).
[PubMed]

Vision Res. (9)

M. A. Georgeson, T. C. A. Freeman, “Perceived location of bars and edges in one dimensional images: computational models and human vision,” Vision Res. 37, 127–142 (1997).
[CrossRef] [PubMed]

P. J. Bennett, M. S. Banks, “The effects of contrast, spatial scale, and orientation on foveal and peripheral phase discrimination,” Vision Res. 31, 1759–1786 (1991).
[CrossRef] [PubMed]

C. M. E. Stephenson, A. J. Knapp, O. J. Braddick, “Discrimination of spatial phase shows a qualitative difference between foveal and peripheral processing,” Vision Res. 31, 11315–11326 (1991).
[CrossRef]

M. C. Morrone, D. C. Burr, “Discrimination of spatial phase in central and peripheral vision,” Vision Res. 29, 433–445 (1989).
[CrossRef] [PubMed]

R. F. Hess, A. Hayes, “The coding of spatial position by the human visual system: effects of spatial scale and retinal eccentricity,” Vision Res. 34, 625–643 (1994).
[CrossRef] [PubMed]

A. Toet, J. J. Koendrink, “Effects of blur and eccentricity on differential displacement discrimination,” Vision Res. 28, 535–553 (1988).
[CrossRef]

P. Mäkelä, R. Näsänen, J. Rovamo, D. Melmoth, “Identification of facial images in peripheral vision,” Vision Res. 41, 599–610 (2001).
[CrossRef] [PubMed]

G. Westheimer, “The spatial grain of the perifoveal visual field,” Vision Res. 22, 157–162 (1982).
[CrossRef] [PubMed]

J. Millodot, C. A. Johnson, A. Lamont, H. W. Leibowitz, “Effects of dioptrics on peripheral acuity,” Vision Res. 15, 1357–1362 (1975).
[CrossRef] [PubMed]

Visual Impairment Res. (1)

E. Peli, “Simple 1-D enhancement for head-mounted low vision aid,” Visual Impairment Res. 1, 3–10 (1999).
[CrossRef]

Other (17)

M. Berkowitz, L. G. Hiatt, P. de Toledo, J. Shapiro, M. Lurie, Characteristics, Activities and Needs of People with Limitation in Reading Print (American Foundation for the Blind, New York, 1979).

E. Josephson, The Social Life of Blind People: a Leisure Activities Study, Research Series No. 19 (American Foundation for the Blind, New York, 1961).

J. Packer, C. Kirchner, “Who’s watching? A profile of the blind and visually impaired audience for television and video” (American Foundation for the Blind, August25, 1997); retrieved 2003, http://www.afb.org/info_document_view.asp?documentid=1232 .

E. Peli, “Head mounted display as a low vision aid,” in Proceedings of the Second International Conference on Virtual Reality and Persons with Disabilities (Center on Disabilities, California State University, Northridge, Calif., 1994), pp. 115–122.

R. C. Gonzalez, R. E. Woods, Digital Image Processing (Addison-Wesley, Reading, Mass., 1992).

J. Russ, The Image Processing Handbook, 2nd ed. (CRC Press, Boca Raton, Fla., 1995), p. 674.

R. G. Hier, G. W. Schmidt, R. S. Miller, S. E. DeForest, “Real-time locally adaptive contrast enhancement: a practical key to overcoming display and human-visual-system limitations,” in 1993 SID International Symposium Digest of Technical Papers, J. Morreale, ed. (Palisades Institute for Research Services, Inc., Seattle, Wash., 1993), pp. 491–494.

E. Peli, E. M. Fine, K. Pisano, “Video enhancement of text and movies for the visually impaired,” in Low Vision: Research and New Developments in Rehabilitation, A. C. Kooijman, P. L. Looijestijn, J. A. Welling, G. J. van der Wildt, eds. (IOS Press, Amsterdam, 1994), pp. 191–198.

E. Fine, E. Peli, N. Brady, “Video enhancement improves performance of persons with moderate visual loss,” in Proceedings of the International Conference on Low Vision, “Vision 96” (Organización Nacional de Ciegos Españoles, Madrid, Spain, 1996), pp. 85–92.

E. Peli, “Perceived quality of video enhanced for the visually impaired,” in Vision Science and Its Applications, Vol. 1 of 1999 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1999), pp. 46–48.

E. Peli, G. Young, E. Lee, C. Trempe, “Effects of distortions due to image enhancement on face recognition,” in Noninvasive Assessment of the Visual System, Vol. 1 of 1992 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1992), pp. 18–21.

N. A. Macmillan, C. D. Creelman, Detection Theory: A User’s Guide (Cambridge U. Press, Cambridge, UK, 1991).

C. E. Metz, P. Wang, H. B. Kronman, “A new approach for testing the significance of differences between ROC curves measured from correlated data,” in Proceedings of VIII Conference on Information Processing in Medical Imaging (Nijhoff, The Hague, 1984), pp. 432–445.

E. Peli, “Wideband image enhancement,” U.S. patent6,611,618 (August26, 2003).

Blurred images were used (1) to prevent “floor” effects, (2) to determine whether degraded images were visible to low-vision patients, and (3) to test the validity of our psychophysical methods.

The graphics tablet collected continuous values, but there were large words on the tablet indicating a rating scale to the patient.

M. Ardito, “Preferred viewing distance and display parameters,” in MOSAIC Handbook (O’Reilly, Sebastopol, Calif., 1996), pp. 165–181.

Cited By

OSA participates in CrossRef's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (8)

Fig. 1
Fig. 1

The image-enhancement algorithm was based on a feature-detection algorithm30 (shown within the dashed lines). The RGB image was converted to luminance, and a bipolar feature representation was generated. An intermediate computation of the bandpass-filtered version of the image, at the feature locations, was used to estimate the magnitude of the underlying feature. This magnitude was used to scale the feature pixel value to be added to (subtracted from, for dark features) the original pixel if the feature was above the threshold of all four filters (phase congruency). The scaled feature values maintained the RGB ratio of the original underlying pixel and thus maintained about the same hue. An individually selected level multiplied the feature pixels’ magnitude before adding them to the original image. For binary enhancement (used during pilot experiments), the contours replaced the original pixels (substitution).

Fig. 2
Fig. 2

(a) Original image. This TV image was particularly sharp and had high signal-to-noise ratio. (b) Degraded image processed with the Adaptive Enhancement algorithm1 with K=0.37. (c) The bipolar edge and bar features of various strengths detected from the original are shown at scale factor 255 (level 9 in Table 1); they were then added to the original image to create the enhanced image in (d). (e) Shown at scale factor 3199 (level 15 in Table 1) are the bipolar edges of various strengths detected from the original that were then added to the original image to create the enhanced image in (f). The selected median enhancement level 7 from 35 patients in procedure 1 was not clearly visible in print even though it was clearly visible on the TV monitor. The high enhancement level shown in (e) and (f) is equivalent to enhancement done with binary substitution.

Fig. 3
Fig. 3

The scores represented by these distributions of the perceived image-quality scores of test images (for the purposes of illustration, bins are 0.5 unit wide, but it is important to note that the ROC analysis does not involve binning). This patient clearly preferred the individually selected (level 9) enhancement (and thus has distributions that were clearly separated). These distributions were used to construct two of the ROC curves shown in Fig. 6(a) below. For simplicity, the second wideband enhancement image set is not shown.

Fig. 4
Fig. 4

Group A patients shown as two subsets. The patients in Group A who did not complete procedure 2 (Group A-D) selected slightly higher levels of wideband enhancement than the patients in Group D (who completed procedure 2) (p=0.02). Most patients preferred a moderate level of enhancement. Note: No patient preferred any of the degraded levels (levels 1–4).

Fig. 5
Fig. 5

Difference between enhancement levels selected on the two repetitions of procedure 1 (group B). Half the patients selected the same level. There was a slight tendency to select a lower enhancement level on the repeat, especially if a high level had been selected on the first. Dashed lines show the mean and 95% confidence limits (CL). Note: Overlapped symbols were shifted slightly horizontally to make them visible.

Fig. 6
Fig. 6

ROC data and fitted curves for two patients. P-proportion is the proportion of the processed images with higher perceived quality, and O-proportion is the proportion of the original images with higher perceived quality. The thick solid curves are the fits to the solid triangular symbols (individually selected enhancement level), and the thin curves are the fits to the open square symbols (second enhancement levels). The dashed lines at the right of (a) and hugging the lower right corner of (b) are the fits to the solid diamond symbols (the degraded images). (a) A 43-yr-old patient (visual acuity 20/250) who clearly favored the wideband enhancement. Here the individually selected enhancement level was 9. The second enhancement level was 7. This patient clearly rejected the degraded image and significantly favored the enhanced images. (b) A more typical example in which Az was only slightly larger than 0.5. This 69-yr-old patient (visual acuity 20/180) had an individually selected enhancement level of 6. The second enhancement level was 8. The degraded level was clearly rejected. Two ROC curves shown in (a) are constructed from the scores represented by the distributions shown in Fig. 3.

Fig. 7
Fig. 7

In procedure 2 (Group D), perceived image quality with the individually selected enhancement, as measured by using Az, was not correlated with visual acuity. Error bars show the asymmetric 95% confidence intervals.37 For five patients (box), the lower bound of the Az confidence interval was greater than 0.5, and those patients were grouped for additional analyses (Group E).

Fig. 8
Fig. 8

Average Az for four image categories from the patients in Group D and Group E. For Group D, while all show a mean Az more than 0.5 (dotted line), the multiple-face category had the highest perceived image quality, and it was the only one that was significantly different from 0.5 (original). For Group E, the five patients showed Az values significantly higher than 0.5 for all four image categories. The error bars represent SEM.

Tables (3)

Tables Icon

Table 1 The 15 Levels Used in Procedure 1 a

Tables Icon

Table 2 Group Characteristics a

Tables Icon

Table 3 Average Face Width in 44 Images of 4 Subcategories a

Metrics