SCTV formula in excel

Ben

Member
Does anyone have an excel sheet to calculate sctv values?

We print in CMYKOGV and use minispots for our process control in excel. We now want to use SCTV to calculate the dotgain for OGV instead of the traditional method.

We use the Techkon spectrodens and when i measure in SCTV mode i get the lab values back from the patches 100/80/60/40/20.

I found the formula online to calculate them but they are not easy. Maybe some of you already figured it out and would like to share the excel file.
 
Hi Ben,
We have printed OGV with SCTV method. The ISO 20654 tells about the SCTV calculations. But as per my knowledge SCTV dot gain values are 50 dot target is 50, 25 dot target is 25. Unlike process colour standards SCTV values are different targets.
 

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  • SCTV_calc_from_cielab.xyz.png
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Ideal SCTV Linear Result in TVI coordinates
 

Attachments

  • Spectralcalc_PNG_image_2020_05_21_00_44_15_AM.png
    Spectralcalc_PNG_image_2020_05_21_00_44_15_AM.png
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Ideal SCTV Linear Result in TVI coordinates
Mihas, did you test the black ink with SCTV formula for F52? I guess you get the same bigger TVI curve. And what about F39? As I know if you go down in the paper classes the difference will be bigger when you measure SCTV calibrated tone values with Murray-Davies formula.
 
No, the SCTV formula is not tied in any way to either the Fogra52 or Fogra39. Yes, depending on a different substrate and a different color of inks, the SCTV curves will be different. The picture shows coated paper.
 

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