Digital BW, The Print

Hi Steve,

This is very strange indeed.  We seem to be dealing with two completely 
different inks.  The LAB data for my Epson PK printed BO on Epson 
premium semigloss are very different from your data.  For example, at 
the 50% patch my ink reads L=55.39, a=1.95, b=4.04 and your data for 
the 50% patch are L=58.55, a=-0.84, b=-5.65.  The Lab a values vary 
along the red to green axis, with positive values tending towards red 
and negative values towards green.  The Lab b values vary along the 
yellow to blue axis with positive values tending towards yellow and 
negative values towards blue.  So, my data for PK at 50% indicate a 
warm tone based on the positive values for both a and b whereas your 
data indicate a decidedly cool tone based on negative values for both a 
and b.  If you want a visual interpretation of these numbers go to the 
color calculator link below and plug in the Lab data (select D50 
illuminant, 2 degrees observer,  and CIE-L*ab color space first) and 
click start.  You will get a table of the data converted to other color 
spaces and a color chip simulation for that patch.

http://www.easyrgb.com/calculator.php

Carl

On Saturday, February 7, 2004, at 08:49  AM, Steve Kale wrote:

> Here are the readings.  I am interested as to how you interpret these,
> Steve.
>
> LGOROWLENGTH    1
>
> CREATED    "2/7/2004"  # Time: 13:46
>
> INSTRUMENTATION    "Eye One"
>
> MEASUREMENT_SOURCE    ""Illumination=D50    ObserverAngle=2°
> WhiteBase=Absolute    Filter=No""
>
> KEYWORD    "SampleID"
>
> KEYWORD    "SAMPLE_NAME"
>
> NUMBER_OF_FIELDS    9
>
> BEGIN_DATA_FORMAT
>
> SampleID    SAMPLE_NAME    GRAY    XYZ_X    XYZ_Y    XYZ_Z    LAB_L    
> LAB_A
> LAB_B
>
> END_DATA_FORMAT
>
> NUMBER_OF_SETS    21
>
> BEGIN_DATA
>
> 1    A1    0.00    85.91    89.21    78.16    95.67    -0.19    -3.90
>
> 2    B1    5.00    76.66    79.28    70.36    91.36    0.44    -4.57
>
> 3    C1    10.00    68.55    70.80    63.12    87.39    0.63    -4.68
>
> 4    D1    15.00    61.23    63.21    57.47    83.55    0.66    -5.67
>
> 5    E1    20.00    55.21    56.98    52.12    80.17    0.68    -5.81
>
> 6    F1    25.00    49.84    51.42    46.90    76.93    0.70    -5.45
>
> 7    G1    30.00    44.65    46.17    42.31    73.66    0.38    -5.51
>
> 8    H1    35.00    39.01    40.45    37.77    69.79    0.04    -6.25
>
> 9    I1    40.00    33.90    35.25    33.46    65.95    -0.32    -6.76
>
> 10    J1    45.00    29.54    30.77    28.86    62.31    -0.50    -5.90
>
> 11    K1    50.00    25.40    26.55    24.92    58.55    -0.84    -5.65
>
> 12    L1    55.00    21.39    22.36    20.76    54.40    -0.78    -4.89
>
> 13    M1    60.00    17.67    18.43    17.19    50.01    -0.54    -4.75
>
> 14    N1    65.00    14.38    14.98    13.72    45.60    -0.35    -3.76
>
> 15    O1    70.00    11.73    12.26    11.17    41.62    -0.64    -3.37
>
> 16    P1    75.00    9.21    9.65    8.65    37.21    -0.77    -2.56
>
> 17    Q1    80.00    6.55    6.86    6.22    31.48    -0.58    -2.63
>
> 18    R1    85.00    4.50    4.68    4.19    25.79    -0.12    -2.01
>
> 19    S1    90.00    2.78    2.94    2.71    19.82    -1.10    -2.31
>
> 20    T1    95.00    1.15    1.21    1.21    10.61    -0.41    -3.12
>
> 21    U1    100.00    0.73    0.77    0.81    6.94    -0.53    -3.21
>
> END_DATA