QTR-Quadtone RIP

Dear All,

How do I figure out the ideal 256 lab values between black and white (where the paper white is density .03, L 97.63 and DMax is density 1.71 and 14.66)? 

I want to know this because Using an Epson 1430 and Eboni 100% and a black only profile on Epson Hot Press Natural I get do not get a perfectly linear lab curve after linearization no matter what I try. The irregularities in the curves are apparent both by measurement and visually with Graham Preston's circular targets. 

Paul Roark's BO curve in his Eboni1400 curve set have the same problems so I figure that its not just me.

I'd figure that I could try and edit the .quad values directly and get a better curve if I knew what the ideal densities were.

As a first step, I have printed a 256 gray target. It takes 2 pages for easy reading with a Spyder3Print spectro and wide margins). Since the Spyder3Print spectra is noisy, I sampled each patch 10 times from two separate printings of the target. The table below gives average of the 5,120 measurements and the quad ink values.

Following the groups advice, I am using QTR print.

Has anyone else fount the Spyder3Print spectra to be noisy? I find that the density values are most consistent, followed by Lab L, and Lab a and b are equally nosiest. I think that (at least for Lab L) that the very dark values are noiser than others.

I've been using 10 samples for each patch and two printings as a practical limit. From series of several hundred measurements of the calibration target and paper white I know that more samples would be better. But I just don't have the patience. I intend to chick the final results with 10 samples from three or four printings of the target.

Any advice would be welcome. 

Thank you,

Vincent

Profile:
PRINTER=Quad1400-Eb
CURVE_NAME=1430-eHPn-Eb_K100

GRAPH_CURVE=YES

N_OF_INKS=6
DEFAULT_INK_LIMIT=35
LIMIT_K=
BOOST_K=41
LIMIT_C=
LIMIT_M=
LIMIT_Y=
LIMIT_LC=
LIMIT_LM=

N_OF_GRAY_PARTS=1
GRAY_INK_1=K
GRAY_VAL_1=100

GRAY_HIGHLIGHT=10
GRAY_SHADOW=10
GRAY_OVERLAP=0
GRAY_GAMMA=1
GRAY_CURVE=

N_OF_TONER_PARTS=0
TONER_HIGHLIGHT=10
TONER_SHADOW=10
TONER_GAMMA=1
TONER_CURVE=
N_OF_TONER_2_PARTS=0
TONER_2_HIGHLIGHT=10
TONER_2_SHADOW=10
TONER_2_GAMMA=1
TONER_2_CURVE=

N_OF_UNUSED=5
UNUSED_INK_1=C
UNUSED_INK_2=M
UNUSED_INK_3=Y
UNUSED_INK_4=LC
UNUSED_INK_5=LM

LINEARIZE="0.03 0.05 0.08 0.12 0.17 0.22 0.27 0.33 0.40 0.46 0.53 0.60 0.66 0.73 0.79 0.86 0.93 1.00 1.06 1.12 1.16 1.21 1.27 1.32 1.39 1.44 1.49 1.54 1.58 1.63 1.69 1.72 1.73"


Measured data:

quad value,100 - Lab l
0,2.13
14,2.53
27,2.85
42,3.25
57,3.65
71,4.04
85,4.45
98,4.78
111,5.14
123,5.54
135,5.94
147,6.19
158,6.52
170,6.86
181,7.14
193,7.53
204,7.77
216,8.19
228,8.59
239,8.82
251,9.11
262,9.43
274,9.72
285,10.09
296,10.41
308,10.75
319,11.01
330,11.29
341,11.64
352,11.87
364,12.34
374,12.57
386,12.71
397,13.10
408,13.51
420,13.74
432,14.09
444,14.42
457,14.77
469,14.96
483,15.47
496,15.35
509,15.94
523,16.31
537,16.82
551,17.16
566,17.58
581,17.94
596,18.14
611,18.69
627,19.20
643,19.57
659,19.95
675,20.28
692,20.44
708,21.01
724,21.25
741,21.66
757,22.17
774,22.54
790,23.28
807,23.51
822,23.83
839,24.07
855,24.49
871,24.90
886,25.29
902,25.69
918,26.03
933,26.19
948,26.39
963,26.54
978,27.02
993,27.38
1008,27.62
1023,28.12
1037,28.42
1052,29.02
1067,29.27
1082,29.58
1097,29.68
1113,30.17
1129,30.73
1145,30.70
1162,30.76
1180,31.10
1198,31.71
1216,31.90
1236,32.13
1256,32.32
1277,32.90
1298,33.10
1319,34.01
1341,34.34
1363,34.97
1385,35.12
1408,35.32
1430,35.88
1452,36.26
1474,36.68
1496,36.73
1517,37.02
1539,37.15
1560,37.66
1581,38.07
1602,37.97
1623,38.71
1644,38.45
1665,39.46
1686,39.75
1707,39.86
1729,40.27
1750,40.54
1772,41.12
1794,41.29
1815,41.60
1838,41.81
1862,41.85
1886,42.20
1910,42.54
1936,42.91
1962,43.19
1989,43.41
2017,43.84
2046,44.62
2076,45.07
2108,45.36
2140,45.66
2173,44.86
2206,45.89
2240,45.93
2274,46.01
2307,46.05
2340,47.01
2373,46.86
2404,47.36
2435,47.27
2466,47.00
2496,46.92
2526,47.52
2557,49.77
2588,49.89
2619,50.04
2652,50.27
2686,50.56
2722,51.42
2760,51.70
2799,51.64
2840,51.46
2883,52.49
2927,52.43
2971,52.86
3015,52.53
3060,52.49
3104,52.47
3147,53.09
3190,55.24
3232,55.82
3273,55.96
3314,56.11
3355,55.97
3396,56.96
3436,57.28
3478,57.22
3520,57.08
3563,57.73
3607,57.96
3652,58.09
3699,57.87
3746,57.16
3793,57.63
3842,57.93
3890,60.00
3939,60.51
3988,60.68
4037,60.87
4086,60.71
4136,61.21
4186,61.75
4238,61.79
4291,61.85
4346,62.36
4404,62.55
4465,62.66
4530,62.77
4597,62.16
4668,62.45
4740,62.89
4814,64.32
4888,64.90
4961,65.12
5033,65.29
5102,64.97
5171,65.54
5241,65.84
5315,66.10
5395,66.43
5486,66.85
5589,67.10
5707,67.11
5839,67.17
5980,67.01
6125,67.24
6267,67.83
6403,68.88
6532,69.55
6655,69.65
6772,69.96
6884,69.89
6993,70.26
7100,70.90
7207,71.04
7318,71.50
7435,71.87
7561,72.23
7701,72.37
7854,72.62
8017,72.67
8182,72.83
8344,73.19
8495,73.81
8631,74.37
8755,74.57
8874,74.82
8993,74.49
9118,74.90
9259,75.34
9419,75.81
9604,76.15
9810,76.57
10032,76.80
10264,77.09
10504,77.24
10747,77.46
10992,77.49
11240,77.84
11488,78.47
11739,78.74
12005,78.98
12298,79.21
12632,78.81
13022,79.74
13453,79.73
13899,80.70
14334,80.98
14748,81.48
15154,81.55
15573,81.87
16020,81.83
16495,81.99
16975,82.06
17432,82.52
17823,82.79
18279,83.03
19830,83.68
26869,84.92

Vincent Wan
August 2012 PhD. Committee on the Conceptual and Historical Studies of Science, University of Chicago.		
Once and future professor of Biology