Abstract

Observer-sensitivity to edge and line blur was examined by measuring just-noticeable differences of blur as a function of contrast, edge-profile shape, line width, and for white lines on black and black lines on white. At high luminance ratios, observers can discriminate a blurred image from an unblurred image when the edge-transition width (10–90% luminance points) is of the order of 25 sec of arc. However, when both images are blurred, they can be discriminated when they differ by as little as 5–10 sec of arc.

© 1981 Optical Society of America

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References

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  1. M. W. Baldwin, “The subjective sharpness of simulated television images,” Bell Syst. Tech. J. 19, 563–586 (1940).
    [Crossref]
  2. O. H. Schade, “Image gradation, graininess and sharpness in television and motion picture systems,” J. Soc. Motion Pict. Telev. Eng. 56, 137–177 (1951).
  3. G. C. Higgins and L. A. Jones, “The nature and evaluation of the sharpness of photographic images,” J. Soc. Motion Pict. Telev. Eng. 58, 277–290 (1952).
  4. G. C. Higgins and R. N. Wolfe, “The relation of definition to sharpness and resolving power in a photographic system,” J. Opt. Soc. Am. 45, 121–129 (1955).
    [Crossref]
  5. M. A. Sproson, “Subjective sharpness of television pictures,” Radio Eng. 35, 124–132 (1958).
  6. N. W. Lewis and T. V. Hauser, “Microcontrast and blur in imaging systems,” J. Photogr. Sci. Eng. 10, 288–301 (1962).
  7. O. H. Schade, “An evaluation of photographic image quality and resolving power,” J. Soc. Motion Pict. Telev. Eng. 73, 81–119 (1964).
  8. E. H. Linfoot, Fourier Methods in Optical Image Evaluation (Focal, New York, 1964).
  9. E. M. Crane, “An objective method for rating picture sharpness: SMT acutance,” J. Soc. Motion Pict. Telev. Eng. 73, 643–647 (1964).
  10. E. M. Granger and K. N. Cupery, “An optical merit function (SQF), which correlates with subjective image judgments,” Photogr. Sci. Eng. 16, 221–230 (1972).
  11. R. G. Gendron, “An improved objective measure for rating picture sharpness: CMT acutance,” J. Soc. Motion Pict. Telev. Eng. 82, 1009–1012 (1973).
  12. C. R. Carlson, “Thresholds for image sharpness,” J. Photog. Sci. Eng. 22, 69–71 (1978).
  13. In active media, such as CRT displays, the parameter of interest is normalized luminance; in most cases involving passive media, such as paper, the luminance values may be taken as representing reflectance.

1978 (1)

C. R. Carlson, “Thresholds for image sharpness,” J. Photog. Sci. Eng. 22, 69–71 (1978).

1973 (1)

R. G. Gendron, “An improved objective measure for rating picture sharpness: CMT acutance,” J. Soc. Motion Pict. Telev. Eng. 82, 1009–1012 (1973).

1972 (1)

E. M. Granger and K. N. Cupery, “An optical merit function (SQF), which correlates with subjective image judgments,” Photogr. Sci. Eng. 16, 221–230 (1972).

1964 (2)

O. H. Schade, “An evaluation of photographic image quality and resolving power,” J. Soc. Motion Pict. Telev. Eng. 73, 81–119 (1964).

E. M. Crane, “An objective method for rating picture sharpness: SMT acutance,” J. Soc. Motion Pict. Telev. Eng. 73, 643–647 (1964).

1962 (1)

N. W. Lewis and T. V. Hauser, “Microcontrast and blur in imaging systems,” J. Photogr. Sci. Eng. 10, 288–301 (1962).

1958 (1)

M. A. Sproson, “Subjective sharpness of television pictures,” Radio Eng. 35, 124–132 (1958).

1955 (1)

1952 (1)

G. C. Higgins and L. A. Jones, “The nature and evaluation of the sharpness of photographic images,” J. Soc. Motion Pict. Telev. Eng. 58, 277–290 (1952).

1951 (1)

O. H. Schade, “Image gradation, graininess and sharpness in television and motion picture systems,” J. Soc. Motion Pict. Telev. Eng. 56, 137–177 (1951).

1940 (1)

M. W. Baldwin, “The subjective sharpness of simulated television images,” Bell Syst. Tech. J. 19, 563–586 (1940).
[Crossref]

Baldwin, M. W.

M. W. Baldwin, “The subjective sharpness of simulated television images,” Bell Syst. Tech. J. 19, 563–586 (1940).
[Crossref]

Carlson, C. R.

C. R. Carlson, “Thresholds for image sharpness,” J. Photog. Sci. Eng. 22, 69–71 (1978).

Crane, E. M.

E. M. Crane, “An objective method for rating picture sharpness: SMT acutance,” J. Soc. Motion Pict. Telev. Eng. 73, 643–647 (1964).

Cupery, K. N.

E. M. Granger and K. N. Cupery, “An optical merit function (SQF), which correlates with subjective image judgments,” Photogr. Sci. Eng. 16, 221–230 (1972).

Gendron, R. G.

R. G. Gendron, “An improved objective measure for rating picture sharpness: CMT acutance,” J. Soc. Motion Pict. Telev. Eng. 82, 1009–1012 (1973).

Granger, E. M.

E. M. Granger and K. N. Cupery, “An optical merit function (SQF), which correlates with subjective image judgments,” Photogr. Sci. Eng. 16, 221–230 (1972).

Hauser, T. V.

N. W. Lewis and T. V. Hauser, “Microcontrast and blur in imaging systems,” J. Photogr. Sci. Eng. 10, 288–301 (1962).

Higgins, G. C.

G. C. Higgins and R. N. Wolfe, “The relation of definition to sharpness and resolving power in a photographic system,” J. Opt. Soc. Am. 45, 121–129 (1955).
[Crossref]

G. C. Higgins and L. A. Jones, “The nature and evaluation of the sharpness of photographic images,” J. Soc. Motion Pict. Telev. Eng. 58, 277–290 (1952).

Jones, L. A.

G. C. Higgins and L. A. Jones, “The nature and evaluation of the sharpness of photographic images,” J. Soc. Motion Pict. Telev. Eng. 58, 277–290 (1952).

Lewis, N. W.

N. W. Lewis and T. V. Hauser, “Microcontrast and blur in imaging systems,” J. Photogr. Sci. Eng. 10, 288–301 (1962).

Linfoot, E. H.

E. H. Linfoot, Fourier Methods in Optical Image Evaluation (Focal, New York, 1964).

Schade, O. H.

O. H. Schade, “An evaluation of photographic image quality and resolving power,” J. Soc. Motion Pict. Telev. Eng. 73, 81–119 (1964).

O. H. Schade, “Image gradation, graininess and sharpness in television and motion picture systems,” J. Soc. Motion Pict. Telev. Eng. 56, 137–177 (1951).

Sproson, M. A.

M. A. Sproson, “Subjective sharpness of television pictures,” Radio Eng. 35, 124–132 (1958).

Wolfe, R. N.

Bell Syst. Tech. J. (1)

M. W. Baldwin, “The subjective sharpness of simulated television images,” Bell Syst. Tech. J. 19, 563–586 (1940).
[Crossref]

J. Opt. Soc. Am. (1)

J. Photog. Sci. Eng. (1)

C. R. Carlson, “Thresholds for image sharpness,” J. Photog. Sci. Eng. 22, 69–71 (1978).

J. Photogr. Sci. Eng. (1)

N. W. Lewis and T. V. Hauser, “Microcontrast and blur in imaging systems,” J. Photogr. Sci. Eng. 10, 288–301 (1962).

J. Soc. Motion Pict. Telev. Eng. (5)

O. H. Schade, “An evaluation of photographic image quality and resolving power,” J. Soc. Motion Pict. Telev. Eng. 73, 81–119 (1964).

E. M. Crane, “An objective method for rating picture sharpness: SMT acutance,” J. Soc. Motion Pict. Telev. Eng. 73, 643–647 (1964).

O. H. Schade, “Image gradation, graininess and sharpness in television and motion picture systems,” J. Soc. Motion Pict. Telev. Eng. 56, 137–177 (1951).

G. C. Higgins and L. A. Jones, “The nature and evaluation of the sharpness of photographic images,” J. Soc. Motion Pict. Telev. Eng. 58, 277–290 (1952).

R. G. Gendron, “An improved objective measure for rating picture sharpness: CMT acutance,” J. Soc. Motion Pict. Telev. Eng. 82, 1009–1012 (1973).

Photogr. Sci. Eng. (1)

E. M. Granger and K. N. Cupery, “An optical merit function (SQF), which correlates with subjective image judgments,” Photogr. Sci. Eng. 16, 221–230 (1972).

Radio Eng. (1)

M. A. Sproson, “Subjective sharpness of television pictures,” Radio Eng. 35, 124–132 (1958).

Other (2)

E. H. Linfoot, Fourier Methods in Optical Image Evaluation (Focal, New York, 1964).

In active media, such as CRT displays, the parameter of interest is normalized luminance; in most cases involving passive media, such as paper, the luminance values may be taken as representing reflectance.

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Figures (8)

Fig. 1
Fig. 1

Sectioned view of an edge image.

Fig. 2
Fig. 2

(a) Stimulus configuration for edge experiments, (b) stimulus configuration for line experiments.

Fig. 3
Fig. 3

(a) Blur thresholds for Gaussian edges as a function of luminance ratio. Observer JH. Maximum luminance, 25.5 fl. (b) Blur thresholds for Gaussian edges as a function of luminance ratio. Observer CD. Maximum luminance, 25.5 fl.

Fig. 4
Fig. 4

Blur thresholds for different edge profiles as a function of luminance ratio. Observer JH. Filled circles are for Gaussian, open circles for exponential, and squares for linear ramp-profile data. Maximum luminance, 25.5 fl.

Fig. 5
Fig. 5

(a) Blur thresholds for 150-arc-sec width lines as a function of luminance ratio. Observer JH. Open circles represent white-lines-on-black, filled circles black-lines-on-white data. Maximum luminance, 25.5 fl. (b) Blur thresholds for 150-arc-sec-width lines as a function of luminance ratio. Observer CD. Open circles represent white-lines-on-black, filled circles black-lines-on-white data. Maximum luminance, 25.5 fl.

Fig. 6
Fig. 6

Blur threshold for lines as a function of linewidth. Observer JH. Lines have Gaussian edge profiles and a luminance ratio of 0.1. Maximum luminance, 25.5 fl.

Fig. 7
Fig. 7

(a) Edge-blur just-noticeable differences as a function of edge-transition width. Observer JH. Open circles represent luminance ratio of 0.5, filled circles a luminance ratio of 0.1. Maximum luminance 25.5 fl. (b) Edge-blur just-noticeable differences as a function of edge-transition width. Observer CD. Open circles represent luminance ratio of 0.5, filled circles a luminance ratio of 0.1. Maximum luminance, 25.5 fl.

Fig. 8
Fig. 8

(a) Line-blur just-noticeable differences as a function of edge-transition width. Observer JH. Open circles represent a luminance ratio of 0.5, filled circles a luminance ratio of 0.1. Maximum luminance, 25.5 fl. (b) Line-blur just-noticeable differences as a function of edge transition width. Observer CD. Open circles represent a luminance ratio of 0.5, filled circles a luminance ratio of 0.1. Maximum luminance, 25.5 fl.

Equations (1)

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Gaussian I ( x ) = I r + ( 1 - I r ) e - ( x / w ) 2 , Exponential I ( x ) = I r + ( 1 - I r ) e - ( x / w ) , Linear I ( x ) = 1 x < 0 = 1 - ( 1 - I r ) ( x / w ) 0 x w = 1 x > w ,