QTR-Quadtone RIP

Sylvain,

Simple question,

In step 1 you used Paul's curve, did it still contain his linearisation figures?

Otherwise you have introduced a new linearization, not corrected it.

Jim Thyer

  ----- Original Message ----- 
  From: Sylvain 
  To: QuadtoneRIP@yahoogroups.com 
  Sent: Friday, February 11, 2011 7:33 AM
  Subject: [QuadtoneRIP] Linearization with a scanner


    
  Hi all,

  I've been printing with paul's curves on Photorag for a whil now, and I'm trying new papers. Since I do not have any spectro, I tried to linearize my profile with my Epson V500 scanner.
  I did it this way:
  1. Printed a 21 step strip on Photorag with Paul's curve, let it dry.
  2. Scanned it (tif, gray levels)
  3. adjusted the picture (with Gimp) to get the white square at 100% and the black one at 0%
  4. adjusted the gamma (1.3), to have all squares (or nearly) at their normal value (100-95-90-85-...)
  5. Printed same strip on new paper with non linearized curve, let it dry.
  6. scanned it with same parameters as 2.
  7. adjusted it: black, white, and gamma to 1.3
  I got the following values: 100-96-90-84-79-72-65-62-60-53-47-45-40-34-27-23-21-19-15-9-0
  8. I put the values in QTR for linearization.
  9. Printed a new strip to check. Bad result. Seems to be too much corrected.

  Question: what did I miss?

  Help!

  Thx :o)



  

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