Abstract

Spectrophotometric data are automatically entered on IBM punched cards by means of a Librascope Digital Readout Unit for the General Electric Recording Spectrophotometer. Conversion to color coordinates is subsequently carried out on an IBM 650 computer. The over-all precision of the spectrophotometer-digitizer-computer system corresponds to 95% confidence limits of about 0.001 in trichromatic coefficients x and y or about 0.7 NBS units of color difference (Adams chromatic value formula, normalized as in ASTM Method D1482-57T). Taking results of the National Bureau of Standards as correct, the accuracy of the average of several measurements is within 0.0005 in trichromatic coefficients or 0.4 NBS units of color difference. The error frequency of the digitizer is currently below 1 in 7000 readouts, and can be reduced to less than 1 in 200 000 readouts.

© 1960 Optical Society of America

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References

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  1. Keegan, Rheinboldt, Schleter, Menard, and Judd, J. Opt. Soc. Am. 48, 863(A) (1958).
  2. F. W. Billmeyer, J. Opt. Soc. Am. 46, 72 (1956).
    [Crossref]
  3. Data were obtained from The Science of Color, Colorimetry Committee, Optical Society of America (Thomas Y. Crowell Company, New York, 1953).
  4. W. D. Wright, J. Opt. Soc. Am. 49, 384(A) (1959).
    [Crossref]
  5. “Tentative method of test for color difference using the General Electric recording spectrophotometer,” ; see also E. Q. Adams, J. Opt. Soc. Am. 32, 168 (1942); D. Nickerson and K. F. Stultz, J. Opt. Soc. Am. 24, 550 (1954).
    [Crossref]
  6. H. Hemmendinger and H. R. Davidson, J. Opt. Soc. Am. 47, 122(A) (1957).

1959 (1)

W. D. Wright, J. Opt. Soc. Am. 49, 384(A) (1959).
[Crossref]

1958 (1)

Keegan, Rheinboldt, Schleter, Menard, and Judd, J. Opt. Soc. Am. 48, 863(A) (1958).

1957 (1)

H. Hemmendinger and H. R. Davidson, J. Opt. Soc. Am. 47, 122(A) (1957).

1956 (1)

Billmeyer, F. W.

Davidson, H. R.

H. Hemmendinger and H. R. Davidson, J. Opt. Soc. Am. 47, 122(A) (1957).

Hemmendinger, H.

H. Hemmendinger and H. R. Davidson, J. Opt. Soc. Am. 47, 122(A) (1957).

Judd,

Keegan, Rheinboldt, Schleter, Menard, and Judd, J. Opt. Soc. Am. 48, 863(A) (1958).

Keegan,

Keegan, Rheinboldt, Schleter, Menard, and Judd, J. Opt. Soc. Am. 48, 863(A) (1958).

Menard,

Keegan, Rheinboldt, Schleter, Menard, and Judd, J. Opt. Soc. Am. 48, 863(A) (1958).

Rheinboldt,

Keegan, Rheinboldt, Schleter, Menard, and Judd, J. Opt. Soc. Am. 48, 863(A) (1958).

Schleter,

Keegan, Rheinboldt, Schleter, Menard, and Judd, J. Opt. Soc. Am. 48, 863(A) (1958).

Wright, W. D.

W. D. Wright, J. Opt. Soc. Am. 49, 384(A) (1959).
[Crossref]

J. Opt. Soc. Am. (4)

Keegan, Rheinboldt, Schleter, Menard, and Judd, J. Opt. Soc. Am. 48, 863(A) (1958).

F. W. Billmeyer, J. Opt. Soc. Am. 46, 72 (1956).
[Crossref]

W. D. Wright, J. Opt. Soc. Am. 49, 384(A) (1959).
[Crossref]

H. Hemmendinger and H. R. Davidson, J. Opt. Soc. Am. 47, 122(A) (1957).

Other (2)

“Tentative method of test for color difference using the General Electric recording spectrophotometer,” ; see also E. Q. Adams, J. Opt. Soc. Am. 32, 168 (1942); D. Nickerson and K. F. Stultz, J. Opt. Soc. Am. 24, 550 (1954).
[Crossref]

Data were obtained from The Science of Color, Colorimetry Committee, Optical Society of America (Thomas Y. Crowell Company, New York, 1953).

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Figures (4)

Fig. 1
Fig. 1

Block diagram of the Librascope Digital Readout Unit, showing connections to the General Electric Recording Spectrophotometer.

Fig. 2
Fig. 2

IBM card format for digitized spectrophotometric data (IBM electrotype No. 177623).

Fig. 3
Fig. 3

Output of IBM 650 computer showing tristimulus values and trichromatic coefficients derived from digitized data. Samples are the four standard filters described in the text.

Fig. 4
Fig. 4

Spectrophotometer chart for daily systems check procedure. Identification of curves: A, 100% line (no sample); B, instrument drift check, lamp off; C, zero line (black card blocking sample beam); D, didymium filter for wavelength check, with 54 sec and 150 sec curves superimposed; E, standard blue filter; F, standard yellow filter; G, standard red filter; H, standard green filter.

Tables (5)

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Table I Illuminant options for integration of digitized spectrophotometric data.

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Table II NBS values for color coordinates of standard filters.

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Table III The 95% confidence limits of observed color coordinates of standard filters.

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Table IV Accuracy of observed color coordinates of standard filters.

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Table V Time required for obtaining color coordinates by various techniques.

Equations (5)

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T c , λ = ( T λ - T 0 , λ ) / ( T 100 , λ - T 0 , λ ) ,
R c , λ = R s , λ ( R λ - T 0 , λ ) / ( R v , λ - T 0 , λ ) ,
X = λ = 1 65 T c , λ E i , λ x ¯ λ , Y = λ = 1 65 T c , λ E i λ y ¯ λ , Z = λ = 1 65 T c , λ E i λ z ¯ λ ,
x = X X + Y + Z , y = Y X + Y + Z .
λ = 1 65 E i λ y ¯ λ = 1 ,