Acrobat Dot Gain 30 Conversion is Changing 100K black to 84K

[pfj]

For offset we convert using the built in Dot Gain 30 setting in Acrobat. Problem is that on some files it changes 100K black to 84Kish. Any guesses why? Our preferred behavior would be for 100K to stay 100K and only the other values to change based on a curve.

 

[Joe]

It is because of the color management profile you are using. Try different profiles.

 

[Alois Senefelder]

jpfulton.



Salient Points: Tone Reproduction (Dot Gain) use...... Percentage % NOT "K"



Regards, Alois



Far too much Computer Language used, instead of the correct Printing Terminology !


"M" is the correct Roman symbol for 1000.00

 

[pfj]

It is because of the color management profile you are using. Try different profiles.

So you're saying the color profile I'm using BEFORE conversion to dot gain??

 

[Macmann]

To be clear, K is short for Black in the CMYK acronym. 100K is solid black, 84K would be a dark grayish tint of black, thereby introducing a halftone dot where none was anticipated.

 

[pfj]

To be clear, K is short for Black in the CMYK acronym. 100K is solid black, 84K would be a dark grayish tint of black, thereby introducing a halftone dot where none was anticipated.

Correct... this is exactly what we are experiencing.

 

[Joe]

So you're saying the color profile I'm using BEFORE conversion to dot gain??

Where are you doing this correction in Acrobat? Color convert?

 

[pfj]

Where are you doing this correction in Acrobat? Color convert?

Indesign -> PDF then I'm using the "Convert Colors" option under "Print Production" in Acrobat.

 

[buckeye]

In your Convert Colors dialog box, try selecting "Preserve Black" under the Convert Options.

 

[Alois Senefelder]

Hello Messrs. Macmann and jpfulton.



I'm well aware that "K" stands for the ..... Black Separation Printer, also that any CMY Ink printed as a solid is measured as 100% NOT as a "K"


So - how do we get a Greyish Black -say according to your terminolgy 84K from CMY Inks ? - from which the result is Brown.



Regards, Alois

 

[pfj]

In your Convert Colors dialog box, try selecting "Preserve Black" under the Convert Options.

We actually do use this option (Preserve Black) every time we convert.

 

[Macmann]

Alois - I figured you knew what K was-just clarifying for the newbs. Please see original post-no mention of CMY, or 1000 brown Romans ;-)

Jpfulton-does this only happen to text or all solid black areas? I suspect what you think is black is really a CMYK build of black, which often times does not include a 100% black. Can you verify in separation preview?

 

[pfj]

Alois - I figured you knew what K was-just clarifying for the newbs. Please see original post-no mention of CMY, or 1000 brown Romans ;-)

Jpfulton-does this only happen to text or all solid black areas? I suspect what you think is black is really a CMYK build of black, which often times does not include a 100% black. Can you verify in separation preview?

UPDATE: Looks like the issue happens after we run through our Quite Imposing Plus automation sequence. We are continuing to troubleshoot.. Specifically looking for some kind of color settings in Quite Imposing.

 

[Ulrich]

@jp

just for curiosity: For which Output Intention do you need dotgain 30?

Ulrich

 

[Joe]

Indesign -> PDF then I'm using the "Convert Colors" option under "Print Production" in Acrobat.

So if the text is CMY=0 and K=100 to start with and I do the following using color convert it converts the text to 0%gray which equals 100% K.

 

[pfj]

@jp

just for curiosity: For which Output Intention do you need dotgain 30?

Ulrich

Not sure exactly what you mean. We are sending to an AB Dick 2340 digital platemaker and printing on an Itek 975pfa (blanket-to-blanket perfector)... whole lotta dot gain.

or maybe you mean from what color profile are we converting to dotgain 30? The InDesign file is set to US Web Coated v2 and our export setting is set to "Do not convert"

 

[pfj]

So if the text is CMY=0 and K=100 to start with and I do the following using color convert it converts the text to 0%gray which equals 100% K.

Sometimes it works for us. As mentioned in my post yesterday afternoon it seems that it works until we run the file through Quite Imposing and then that's screwing it up. If we convert to after it's imposed some random folio lines/page numbers disappear... that's why we've taken to always imposing AFTER the convert. We could try to upgrade to the newest version of QIP I suppose.

 

[Ulrich]

@jp
i mean the „normal“ dot gain for K on coated is around 16% and Uncoated is about 22% (sheetfed)...

Did not you calibrate your Platesetter or are you using FM? Guess i had to search for your Itek-machine before asking ;-)

Ulrich

 

[jrhmobile]

I think the more important question is whether you're getting 84K max in images and color builds, or if you're getting 84% screened type.

Type might be an issue, but at 30% dot gain, you're going to get a solid black build on press. Run that deeper on anything but stand-alone type and you're going to get Kbleed into areas where you don't want that black. Because if you're running that deep a dot gain profile, like newsprint-class profiles, you're running on a substrate like a sponge that'll just drink that black ink up.

 

[pfj]

Well... I figured it out. I had to wipe and reinstall my computer from scratch a few months ago... same for the other guy that does prepress. When I was setting them back in I forgot to modify the 'Appearance of Black' setting in InDesign. Now I have it set to "Display all blacks accurately" and "Output all blacks accurately" and it seems to have solved my problem.

The thing that was throwing me for a loop is that the problem was only presenting with some of our files and not all of our files. (to complicate things many of "our" files incorporate novice customer artwork). Thanks all.