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Yes Daniel, of course. You are right about the procedure, but I canshow you, with a practical example, the differences concerning agrayscale profile on the same paper made a month ago and another made afew days ago. You can notice how dark patches have substantially randomvalues for color coordinates, in particular "b" values. The contiguityof "a" and "b" values in the dark side of the curve is completely lost,the standard deviation is changed... and my procedure to creategrayscale or ICC profiles is always the same. Usually, how many timesyou read a patch making a profile? I read the patches in sequence, thenif I want, I repeat reading and calculate the average. Well, now I haveto do the average of 4 or 5 reading in a grayscale to get an acceptablecurve. Something is happened, do not you think so?
Thanks for reply.
Daniel

(sorry for proportional characters, I have adjusted the alignment for a better graphical view)

OLD PROFILE
Step Dens Lab A B
0.00 0.024 97.84 1.26 -2.09 - b ; | a L +
2.00 0.071 93.86 1.74 -2.70 - b | a ; L +
4.00 0.115 90.19 ; 1.19 -2.49 - ; b | a ; L +
6.00 0.153 87.16 1.33 -2.25 - b | a L +
8.00 0.191 84.17 0.91 -2.00 - b | a ; L +
10.00 0.235 80.82 1.79 -2.36 - b | a L +
12.00 0.273 78.09 2.22 -2.77 - b | a L +
14.00 0.315 75.07 2.36 -3.22 - ; b | a L +
16.00 0.359 72.03 2.92 -3.56 - b ; | a L ; +
18.00 0.401 69.28 2.30 -3.17 - b | a L +
20.00 ; 0.456 65.77 1.94 -2.79 - b | a L ; +
22.00 0.502 62.90 1.85 -2.74 - b | a +
24.00 0.547 60.24 1.31 -2.31 - b | aL +
26.00 0.596 57.41 1.02 -2.04 - ; b | a +
28.00 0.645 54.68 0.78 -1.70 - b | La +
30.00 0.684 52.61 0.89 -1.57 - b |L a +
32.00 0.733 ; 50.10 1.08 -1.80 - b L a +
34.00 0.780 47.73 1.30 -2.50 - b L | a +
36.00 0.819 45.85 1.01 -2.17 - ; b L | a +
38.00 0.880 43.02 0.66 -2.82 - b L | a +
40.00 0.940 40.38 0.31 -2.96 - b L |a +
42.00 0.992 38.17 0.23 -3.26 - b L a +
44.00 1.041 36.18 0.35 -3.52 - b L |a +
46.00 1.102 33.80 0.15 -3.09 - b L a ; +
48.00 1.149 32.02 0.53 -2.15 - ; L b | a +
50.00 1.195 30.36 0.49 -1.88 - L b |a +
52.00 1.239 ; 28.82 0.75 -1.52 - L b | ; a +
54.00 1.269 27.80 0.78 -1.57 - L b | a ; +
56.00 1.311 26.40 0.71 -1.37 - ; L b | a +
58.00 1.354 25.04 0.96 -1.51 - L b | a +
60.00 1.390 23.90 0.85 -1.30 - L ; b | a ; +
62.00 1.420 23.00 0.92 -1.33 - L b | a +
64.00 ; 1.457 21.91 0.92 -1.28 - L b | a +
66.00 1.490 20.96 1.11 -0.62 ; - L b | a ; +
68.00 1.522 20.07 0.78 -0.46 - ; L b | a +
70.00 1.554 19.20 0.83 -0.20 - L b| a ; +
72.00 1.591 18.22 0.79 -0.12 - ; L ; b| a +
74.00 1.634 17.10 0.48 -0.04 - L b|a +
76.00 1.682 15.89 0.60 -0.30 - L b | a +
78.00 1.720 14.98 0.53 -0.57 - L ; b | a ; +
80.00 1.754 14.19 0.11 -0.84 - L b a +
82.00 1.791 ; 13.33 0.11 -0.78 - L b a +
84.00 1.830 12.47 0.22 -1.00 - L b a ; ; +
86.00 1.861 11.81 -0.18 -1.10 - L ; b a| +
88.00 1.885 11.29 -0.22 -1.23 - L b a| +
90.00 1.929 10.40 -1.07 -1.03 - L ; b | +
92.00 ; 1.976 9.45 -1.34 -1.24 - L ab | +
94.00 2.005 8.90 -1.17 -0.81 - L ab | +
96.00 2.054 7.98 -1.24 -0.29 - L a b | +
98.00 2.080 7.51 -0.89 -0.24 - L a b| ; +
100.00 2.083 ; 7.46 -0.35 0.19 - L a b ; +

NEW PROFILE
Step Dens Lab A B
0.00 0.016 98.58 1.37 -1.94 - b | a L+
2.00 0.066 94.30 1.72 -2.63 ; - b | a L +
4.00 0.110 90.57 1.18 -2.51 - ; ; b | a ; L +
6.00 0.148 87.58 ; 1.18 -2.07 - b | a L +
8.00 0.186 84.60 0.80 -1.86 - b | a L +
10.00 ; 0.231 81.15 1.79 -2.34 - b | a L +
12.00 0.267 78.47 2.23 -2.66 ; - ; b ; | a L ; +
14.00 0.310 75.43 2.24 -3.02 - ; b | ; a L +
16.00 0.355 72.33 2.93 -3.50 - b | a L +
18.00 0.396 69.59 2.14 -3.09 - b | a L +
20.00 0.449 66.17 1.92 -2.86 - b | a L +
22.00 0.495 63.36 1.70 -2.58 - ; b | a L +
24.00 0.541 60.59 1.26 ; -2.26 - b ; | aL +
26.00 0.590 57.78 1.05 -1.95 - b | a +
28.00 0.639 55.01 0.68 -1.77 - ; b | aL +
30.00 0.677 ; 52.99 0.80 -1.63 - b |L a +
32.00 0.726 50.46 0.89 -1.78 - ; b L a ; +
34.00 0.772 48.16 1.20 -2.45 - ; b L | a +
36.00 0.808 46.38 0.71 ; -1.99 - b L | a +
38.00 0.872 43.40 0.59 -2.90 - b ; L | a ; +
40.00 0.931 40.77 0.20 -2.88 - b L a ; +
42.00 0.979 38.72 -0.24 -2.79 - b L a| +
44.00 1.029 36.66 0.20 -3.44 - b L a +
46.00 1.089 34.30 -0.24 -2.56 - bL a| ; +
48.00 1.139 32.39 -0.25 -1.53 - L b a| +
50.00 1.184 30.75 0.31 -2.03 ; - L b ; |a ; +
52.00 1.230 29.14 -0.10 -0.63 - L b a| +
54.00 1.258 28.16 0.98 -1.80 - L b | a +
56.00 ; 1.301 26.73 0.61 -1.44 - L ; b | a ; +
58.00 1.342 25.40 0.79 -1.29 - L b | a +
60.00 1.380 24.21 0.79 -0.78 - L b | a +
62.00 1.410 23.32 ; 0.41 -0.59 - L b |a +
64.00 1.448 22.17 0.05 -0.20 - L ba +
66.00 1.483 21.17 0.49 0.08 - L ba +
68.00 1.512 20.36 0.76 0.09 - L b a +
70.00 1.549 19.34 0.46 ; 0.49 - L ; |b ; +
72.00 1.570 18.76 0.71 -0.46 - ; L ; b | a ; +
74.00 1.625 17.32 0.65 0.15 - L b a +
76.00 1.679 15.98 1.18 -1.34 - L b | a ; +
78.00 1.706 15.31 0.20 0.10 - L ; b +
80.00 1.751 14.25 -0.56 0.26 - L a |b ; +
82.00 1.773 13.74 0.86 -1.49 - L ; b | a ; +
84.00 1.813 12.84 1.05 -1.05 - L b | a ; +
86.00 1.851 12.01 -0.14 -1.50 - L ; b a| +
88.00 1.893 11.13 -1.88 0.52 - L a | b +
90.00 1.910 10.78 -0.98 -1.14 - L ba | +
92.00 1.959 ; 9.80 -0.11 -1.64 - L b a| +
94.00 1.982 9.33 0.45 -2.39 - L b |a ; +
96.00 2.053 8.00 -2.54 2.35 - L a | b +
98.00 2.052 8.02 0.61 -1.75 - L b | a +
100.00 2.053 7.99 0.05 -0.40 ; - L b a +

The Lab values are not in order.
Cannot make a profile.

--- In colorvision_group@yahoogroups.com, Daniel Vézina wrote:
>
> Posted by: "nadar1900" nadar1900@... nadar1900
> Wed Feb 11, 2009 11:24 am (PST)
>
> >This is evident, I have been unlucky with Datacolor, then I will try
> >another brand.
>
> Don¹t jump in the air too rapidly... You¹re trying to read a very dark patch
> right?
>
> Your readings are:
>
> > 1) 7,99 | -2,91 | 1,26
> > 2) 8,25 | -1,29 | -0,9
> > 3) 8,11 | -0,85 | -1,1
> > 4) 8,29 | -0,22 | -2,13
> > 5) 8,00 | -1,47 | 1,28
>
> You said that you¹re waiting 5-10 seconds betwee (Message over 64 KB, truncated)

Datacolor User to User Support Group.

Re: RE:Sudden loss of accuracy of Datacolor #1005 after 2 years

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