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High ink coverage

bonniewh4

New member
Hi;
I have a drop on demand inkjet printer, I am trying to print a file that has high ink coverage (380%). I want to pull back the ink to 170%, and I don't want to lose th color integrity I tried doing this in Photshop and the color looked washed out and flat. Any suggestions?

thanks
 
Re: High ink coverage

Hi Bonnie,

First, Photoshop is not the tool to reduce ink coverage, uless you use specificly made ICC profile to do so.
170% ink coverage is too low. you can’t even make a red with this ink reduction!

The best way to manage ink redcution is with ICC profile creation tools or DeviceLink / ink saving tools, NOT with curves!

Hope this help!

Louis
 
Re: High ink coverage

I opened the photo in Photoshop changed my CMYK working space to
custom, set the black ink limit to 85 and the Total Ink Limit to 200
(Photoshop doesn't let you put in a lower number) then converted the
color space to RGB, then back to CMYK. That made the Total ink 200 in
the darkest areas so to bring it down even further, I made some
manual adjustments using various other tools.
 
Re: High ink coverage

As Louis mentioned, an ink limit less than 200% excludes all of the purely saturated secondary colors (red, green and blue) because you couldn't have 100% of two colors. If you absolutely must have an ink limit less than 200%, and you don't have a color profile designed to do this, I would suggest using the custom CMYK method with the 200% limit, and then adjusting the image with levels or curves to linearly scale the values so that they range from 0% to 85% (in the case of a 170% limit). You could do this by moving the 100% output point to 85% in the "CMYK" (all channels) channel in the curves window. This would sort of be a simple equivalent of an absolute colorimetric conversion, and would somewhat preserve the relative differences between colors.
 
Re: High ink coverage

Don't know how much of a difference it would make but I've read that cmyk to lab back to cmyk is better than cmyk to rgb back to cmyk.

Edited by: Erik on Jul 24, 2008 2:29 PM
 
Re: High ink coverage

That is exactly what happens when colors are converted from one CMYK profile to another (unless the profile connection space of one of the profiles is XYZ, or a device link profile is used). When you convert from CMYK to RGB and back to CMYK, the conversion is really CMYK > Lab > RGB > Lab > CMYK because Lab (for most profiles) is the absolute color space used to translate the values. Therefore, I agree that using RGB as intermediary is not a good thing, and would introduce some unnecessary gamut reduction.
 
Re: High ink coverage

One other way you can reduce the max density is to open the file in Photoshop and create a selective color adjustment layer. On the top box: colors, select the closest color to the one you are trying to adjust, probably black. Then reduce your 3/c and maintain your black or increase the black if needed, until you get to 200 density. With a rich black, make sure you keep your values neutral.
 
Re: High ink coverage

Jeff you are assuming that the Grey balance is identical from the CMYK profile you have in to the out profile?
The big problem wit the method is that it is so difficult to see TIC/TAC values in PS with only the pipette/spot measurement rather than area (which you get by converting to RGB/LAB and using gamut warning)

If you go LAB, you may want to convert your image to 16 bit before you start the conversion (and finish up with reducing to 8 bit when done)
 
Re: High ink coverage

might want to check out Alwancolor CMYK Optimizer. It has done wonders in out automated workflow to get rid of high ink coverage without changing the color of the files. I think there is a free trial for it.
 
Re: High ink coverage

BTW your InkJet you are printing with, do you have a RIP or you print straight out of PS? I also I realised I didn't ask how you pull back the ink in PS. You may need to generate a profile with your Ink Limit, and with a pullback from 380 to 170 you will not get full gamut coverage/color integrity. Should have adressed this more specifically earlier on rather than going in a generic discussion on how to limit ink. Sorry for not beiing as precice as I could have been.

If you can get or have an ICC with your Ink limit and it is a one time situation I would go for CMYK to LAB to CMYK.
Before turning it to CMYK the second time I would use the proof preview with my desired output and use the help of gamut warning to identify areas that may appear flat. Personally I would use an adjustment layer (possiby after turning the file to 16-bit) to manually get better control over how out of gamut areas are taken in gamut. Hope this is not too late… and if it is hope it will be usefull for the next person.
 
Another player entering the Ink Save market is OneVision with a plug in to their Speedflow or Asura file normalisation software. I work for a pre-press house in Australia and we are a reseller for their software. I have a copy of OneVision's software on my laptop. Rather than make any claims about how good this option is verses others, I'd like to offer to run any file through InkSave and provide the output file. The advantage of OneVision's offer is that the InkSave is not profile based (i.e. it's a 4D to 4D conversion) so no matter what output device is intended to be used you don't need the vendor to supply a special set of ink save profiles specific to each device.

I make to offer to have any file passed through OneVision's most current version of InkSave as it also allows me to confirm with real customers that the technology works. I have an FTP site so if anyone does have a test file they want me to test for them, just contact me and I'll provide the details.

Regards,
Smitty
 
I make to offer to have any file passed through OneVision's most current version of InkSave as it also allows me to confirm with real customers that the technology works. I have an FTP site so if anyone does have a test file they want me to test for them, just contact me and I'll provide the details.

Regards,
Smitty

Hi Smitty,
We also have real customer who made real life tests (press run) and saw that our technology works. They’ve run half job with PerfX Device Link Pro™ ink saving from TGLC inc., and half job without. The complate job was 750,000 copies. They took the weight of each ink tanker, before and after for each half of the job and then, they compared the results.

The results: 26% ink saved for that job on a web offset press for magazine!

Louis
 
Hi forgot to say that this was made without any external or dedicated processing server. Just client’s existing workflow, compatible with ICC DeviceLink profiles.

Simple!

Louis
 
It's not a comparison to another product if you only ran one?

What if the file was crap from the customer in the first place, you would need both a preflight application to correct the file, then a separate application to ink save it.

The advantage OneVision has is that the one software can fix the customer's file and the ink save settings is read from the selected profile (TAC separations etc).

The reality is that around half the files a typical printer or publisher receives will have some issues with it (wrong TAC, missing fonts, images in wrong colour space, etc.). What money and productivity is lost when files need to be worked on?

For any printer in Australia wanting to compare products for real, contact me and I'll arrange an evaluation copy of OneVision's software at your site. It works with any press and needs no additional hardware like some other applications.

Regards,
Steve Smit
 
It's not a comparison to another product if you only ran one?

Regards,
Steve Smit

Not only ran one! This is only an example of what it can do. IT’s been tested and used for web press, newsprint, commercial printing, wide format ink jet, and screenprinting.

Hope it is more clear.

Louis
 
Louis,

Sorry I meant run press tests of Ink Saved files that were processed by a variety of Ink Save software vendors. In other words, comparing the ease of use and results of the alternatives.

Sorry for the missunderstanding.

Smitty
 
The reality is that around half the files a typical printer or publisher receives will have some issues with it (wrong TAC, missing fonts, images in wrong colour space, etc.). What money and productivity is lost when files need to be worked on?

Does it fix "palced the wrong image", spelling mistkes and "didn't update telephone number"? Just wanted to make the point that totaly relying on machines is going to spin so fast it really hurts when you get a call to stop the press. Human intelegence, especially those with real lide experience is hard to replace with automation. Complement = Yes: Replace = No
 

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