Digital BW, The Print

pr_roark schreef:
> Ernst Dinkla <edinkla@...> wrote:
>> ...
>>
>> Straight but inclining, high end to the right, so warmer.
>>
>> Measured the 310gsm on a black tablet with the Spectrocam:
>>
>> Lab 96.03  0.16 1.63
>>
>> the 210gsm
>>
>> Lab 95.87 0.02  0.80
> 
> 
> I'm not sure how accurate my spectro is in the very neutral area, but those Lab A values look lower than most, but it might be my spectro that is reading high.  In general, among the papers I use, I tend to like a somewhat relatively elevated Lab A.  
> 
>> ...
>> http://www.pigment-print.com/spectrumplot/index.php
> 
> There are some interesting dips on some of those graphs.  It makes me wonder what is in the paper or coating that is absorbing light in a narrow band.  Interesting stuff, but a bit hard to relate to on first exposure.
> 
> Paul
> www.PaulRoark.com 
> 
> 

Paul,

Ignore what happens in the 500-550 range. The Xenon flash on the 
Spectrocam has a small peak there that is compensated in the software on 
the white calibration step. I check the white calibration then by 
measuring the calibration patch again and then it is dead on.
Measuring paper white goes well but that range either shows dips or 
peaks and it is more exaggerated in the curve fitting on the website 
than on the original Spectrocam software. I think related to the short 
intervals = 5Nm of the Spectrocam's measurements.

-- 
Met vriendelijke groeten,   Ernst


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