using xrite to scan digital colours

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bubbles
Posts: 12
Joined: Sat Apr 07, 2012 9:13 am

using xrite to scan digital colours

Post by bubbles »

hello guys
just wondering how accurate is the xrite on digital press
we scan are colours on flexo 98% scan .04 1.5 and the colours
look good but on the digiyal press it scanning at 4 but the colour
looks good
Frank Burgos
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Re: using xrite to scan digital colours

Post by Frank Burgos »

Hi Bubbles,

The colors should look very much the same. Can it be that you're using a different color space to measure digital vs. flexo?

For exmple, recently, a client of mine had been keeping things at 2.0 or less, DE Lab. However, they got some new stuff in and set the space to DECMC. A DE of 2.0 was now too tight, so they had to relax it a bit. In any case, confirm this point.

Also, are you printing on the same substrates? Same pigments? Hey, ink guys. Give me a hand here! :smile:
bubbles
Posts: 12
Joined: Sat Apr 07, 2012 9:13 am

Re: using xrite to scan digital colours

Post by bubbles »

Hi Frank
Same substrate they are making a colour out of process yellow magenta cyan black i.e pantone 185
you can get the colours in pre mixed .
How do u find out about the pigment just ask the suppliers .
I think its DECMC ill check that out.
its extremly very tight on flexo colours lets say
it scans 1.5 on the blue side it needs yellow ur talking
sometimes 4grams yellow into 5kg mixbut if you read it wrong
and put in 8grams it shoots up 1.5 on the yellow then uend up putting
in 100g off white totry get it back. probely tolerence im trying to get to
tight between .3 .15 just like what u guys think
Frank Burgos
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Re: using xrite to scan digital colours

Post by Frank Burgos »

Hey Bubbles,

Yeah, I'd confirm the color space, to make sure you're not shooting for tolerances that are unecessarily tight. If you can find out anything about the pigments, that would be a bonus.
mladen
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Location: Croatia

Re: using xrite to scan digital colours

Post by mladen »

Scale of delta error for CIE Lab (1976)

1 - minimal difference, but hardly sustainable in the press
2 - barely visible differences, common for printing
3 - the difference is visible, the advantage is a little time for correction
4 - a clear difference, but in agreement with the buyer can be tolerated
5 - annoying differences - not acceptable for most customers
Frank Burgos
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Re: using xrite to scan digital colours

Post by Frank Burgos »

Excellent and elegant! Thanks!
Fatbelly
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Joined: Mon Jul 02, 2012 7:26 am

Re: using xrite to scan digital colours

Post by Fatbelly »

In a CMC tolerance a DE of 1.0 is defined as being the smallest difference a normal person will notice. Aiming for 0.3 is pointless if your customer cannot see it.

CIE Lab is pretty old and CMC is more useful in real life. Usually in CMC the difference in the L value is adjusted to reflect how our eyes work - we notice a difference in light/dark more than a difference in hue or colour strength. This means that the tolerance is an eliptical space and the size of the elipses varies in different colours. (But note you can adjust the ratio of L to a&B if you need to).

In CIE Lab (or CIE Lch) a colour tolerance DE of 1.0 is different depending on which colour you are looking at. The tolerance is spherical and the same throughout the colour space.

If you look at a real life spectrum or the colour space diagram you will notice that yellow takes only a little of the space (or bandwidth) - BUT, we can see as many shades of yellow as we can of red or green, our eyes are more sensitive to yellow. That's why the yellow always looks good and you should never run an ink trial with just yellow!

This is a diagram of CMC DE tolerances, note that the elipses are bigger in some parts of the space.

Image
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