Plate / Calibration Curves

[C2C]

OK i have 2 sets of Numbers for the same data. ( This is my Target Data right? ) (What we Want it to be)

Which is the correct process?

*also i notice I get into negative values.. is this allowed / acceptable?*

First is: take the 50% dot value of 75.73 ( in Cyan ) - 15% = 61.73%

Second: take the 50% dot : 50-11.25 = 38.75%


or am i still not catching on here
( oh that is very possible indeed~! )

Edited by: C2C on Nov 26, 2007 5:16 AM

[PeterA]

I suppose I am as lost as you -

I would open the Harmony curve used to image the UV plate and against the 10 20 30 40 50 60 70 80 100 should be numbers which you have put in previously to correct the dot -

make a copy of that file

and in your case reduce what ever number is in the 50% box by (15% of 75%) 11.25% ie if its 45 it should be - 5.1% = 39.9

its always a bit hit and miss become the value on the printed sheet is taken as a percetange of the solid - so it they put more ink on the sheet the dot gain goes up

Peter
If no harmanony curve was used to image the plate - then you assume that 50% =50% on the plate

[C2C]

I did an error in my math .. hense the negative values i received ( ok so I wasnt thinking too clearly .. 3 hrs sleep... any other excuse i can give? )

Ill correct this and keep anyone whos watching this thread posted

Thanks Again,

C2C

Edited by: C2C on Nov 26, 2007 11:17 AM

[PeterA]

mmmmmmmmmm
what is this sleep thingeee its usually red wine that causes that :-)

[C2C]

Red Wine just gives me the Worst Headache then hangover ... Evil.

__________________________________________________ ______________________________________________
"and in your case reduce what ever number is in the 50% box by (15% of 75%) 11.25% ie if its 45 it should be - 5.1% = 39.9"
__________________________________________________ ______________________________________________

Using the example given
wouldnt 45 ( for me) be:

[1]
71.34 x 0.15 = 10.70 ( 10.70 being 15% of 71.34)
71.34 x 10.70% = 7.63 *---------------------------------------> Why did I multiply here? (( in your example 45 x 11.25 = 5.1 ))*
71.34-7.63 = 63.71

*OR is it:*

[2]
71.34 - 10.70 ( 15% of 71.34) = 60.64



Im thinking #2 is the value I place in the 45 box.





* I just lost a little more hair

[PeterA]

I think we need to start again

if the 50% digital dot actually reads = 45 on the plate and 71 on the ptd sheet - then 64 on the printed sheet should about 38% on the plate

because 64 is 86% of 71 and 38 is 86% of 45.

Peter

[C2C]

[quote]

I think we need to start again

if the 50% digital dot actually reads = 45 on the plate and 71 on the ptd sheet - then 64 on the printed sheet should about 38% on the plate

because 64 is 86% of 71 and 38 is 86% of 45.

[ end quote]


Ok . Thank you for being so patient! I have emailed the Kodak guy for assistance but hes on vacation atm : (

Ill have to wait till I am at work but will post back here shorty

So im not looking to reduce the printed value by 15% , but the plate value before it hits the presses, do I have that correct?

[PeterA]

Ok
So you have a reading for the 50% patch on your colour bar and you want to cut it back to 60%

IF the 50% digtal dot is the same as that is on the plate

Then the 50% has grown by 50% during the printing process (a coincedence) to 75%

So the 50% dot on the plate should be reduced to 40% so that when it grows it will get to 60%

Peter

<<< 60% is quite low in commercial printing - in Europe its about 64% and in the States 70% ish

[C2C]

{quote}
if the 50% digital dot actually reads = 45 on the plate and 71 on the ptd sheet - then 64 on the printed sheet should about 38% on the plate

because 64 is 86% of 71 and 38 is 86% of 45.
{quote}

Shouldn't the 50% digital dot read 50% on the plate (if no curves are applied prior to imaging) or am I wrong on this aswell ? (lots to learn!)
I understand the reading of 71.34 on the printed sheet due to dot gain.


> {quote:title=PeterA wrote:}{quote}Ok
> So you have a reading for the 50% patch on your colour bar and you want to cut it back to 60%
>
> IF the 50% digtal dot is the same as that is on the plate
>
> Then the 50% has grown by 50% during the printing process (a coincedence) to 75%
>
> So the 50% dot on the plate should be reduced to 40% so that when it grows it will get to 60%
>
> Peter
>
> &lt;&lt;&lt; 60% is quite low in commercial printing - in Europe its about 64% and in the States 70% ish
>

But mathematically its correct isnt it?
Please correct me if Im wrong in my thought process here:

Accoring to the attached pdf:

When printed our 45% Cyan dot reads 71.34 on our press. That means we gained 26.3 % dot on the press.
Going back to the math stated earlier: <span class="largetext">71.34 - 10.70 ( 15% of 71.34) = 60.64

I should be setting the value of 60.64 in our 45% Box in the Cyan for the Target Curve + using the Current Curve .. Harmony *should* now create a Calibration curve with 45% Cyan dot that will end up with a reading of 60.64 on the press sheet. (10.70 being a 15% cutback of the press sheet reading of 71.34)


C2C


ps. Are you frustrated yet? I would be
But I do appreciate the help.

Edited:
and I thought I was getting somewhere... Plate Curve: 1 C2C: 0