Hi Gordo, so would you agree with terrywyse? Like I said, I am new to this, but I always thought that you'd want to make up for the dot gain on press by reducing the dot size. If I do what terrywise is suggesting, won't my dot sizes increase? Attached is the output curve I printed out from the Curve software.
If I understand correctly what Terrywyse wrote, the Curve software - not Harmony - is providing the plate curve values. I might be wrong, however I don't think that what he suggests would work. Harmony does not care what dots are on the plate, nor whether the plate is linear or not (uncalibrated plates are preferred).
Harmony simply looks at what was requested in the PostScript/native application file and what was delivered in the press work (current curve). The dots on the plate are not relevant. They are not considered.
From those two pieces of information - what you asked for in the file and what you got on the press sheet - Harmony then creates a look up table to remap requested tones to the tones that will give you the result you wanted.
Put another way. For example.
• In my file a 50% tone is specified. When I printed that requested 50% I got 80% (80% is a point on the "current" curve) on the press sheet.
• However what I want is that when I specify 50% in my file I expect to get 68% (68% is a point on the "target" curve) on the press sheet. Assuming that 18% is the industry standard dot gain.
• Harmony then looks at which requested tone in the file resulted in a 68% tone in the press work.
• Perhaps a 40% tone in the file ended up as 68% in the presswork.
• Harmony then builds a look up table that will remap any file request for 50% to a request for 40%.
The result is that when I specify a 50% tone in my file I get the 68% target tone in my presswork.
This blog post explains it more deeply and includes illustrations:
Quality In Print: dot gain
So, what you/Harmony need is:
1) a target curve - the tone response you want to achieve in your press work.
2) a current curve - the tone response that you are getting when you simply output an uncalibrated plate and run it on press.
Harmony will the use 1 and 2 to build the lookup table so that you get the tone response that you want in your presswork.
Make sense?
(with apologies) best, gordon p
BTW Harmony is not based on the idea of "making up for dot gain" It is based on the idea that you have a target tone response that you wish to emulate that is different from your current tone response. There could be dot gain, or dot loss involved. It doesn't matter because it doesn't matter to the user what dot gain or loss they have in their system. What matters is that they get what they want according to what they asked for. So, you could have different screens, e.g. 20 micron FM and 100 lpi AM, which would have different dot gains but still give the same final tones on press. I.e. if I ask for 50% I would get 68% on the press sheet despite the dot gains being different.
