Ink levels, posterization, etc.

KC
Posted By
Kent_Chiarelli
Nov 19, 2003
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893
Replies
12
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Closed
Got 2 questions about "shop",

1. Does too much manipulation lead to posterization in print?
2. What are some good guidelines in controlling ink levels in your images?

I’ve recently had a few images that seemed fine in soft proof, but printed like crap, posterized all over.

Second prob was that in some instances, I get heavy inking that requires longer dry time.

Anyone?

Thanks
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ink level posterization

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todd young
Nov 19, 2003

1) no..i think your problem sounds like a postscript issue possibly

2) that sounds like you need to check to make sure youre setting your printer setting correctly for the type of media, etc….check your printer documentation for that

wrote in message
Got 2 questions about "shop",

1. Does too much manipulation lead to posterization in print?
2. What are some good guidelines in controlling ink levels in your images?

I’ve recently had a few images that seemed fine in soft proof, but printed
like crap, posterized all over.
Second prob was that in some instances, I get heavy inking that requires
longer dry time.
Anyone?

Thanks
L
LenHewitt
Nov 19, 2003
1. Does too much manipulation lead to posterization in print?<<

Severe changes of Levels and Curves can have that effect – you will see gaps in the levels histogram indicating missing tones.

What are some good guidelines in controlling ink levels in your images?<<

Your CMYK working profile. In Edit>Colour Settings select CUSTOM in the CMYK Working Space drop-down. From the d/box that opens you can set total ink, dot gain etc.
JS
John_Slate
Nov 19, 2003
exactly how are you printing them?

From "shop" or placed in a layout? File format?

To what type of printer? Give specs.
KC
Kent_Chiarelli
Nov 19, 2003
Thanks for the replies gentlemen.

In response:

1. Edited in shop, saved as TIFF. Converted to PDF for xport, then back to TIFF from Acrobat 6, then sent to RIP.

2. Printing to an Ilford 850i, using RipStar 5.5, max ink levels set to 270 in RipStar.

Sidenote, the posterization I get does not appear in soft as it does in print. No wild moves with curves to cause it, histogram doesn’t look terrible. Happens in the shadow areas and renders the file unuseable. Doesn’t happen to all files, so it has to be the individual files that are out of whack. Wish I could send one along so it could be analyzed by someone with more knowledge.

Thanks again
L
LenHewitt
Nov 20, 2003
Kent,

Converted to PDF for xport, then back to TIFF from Acrobat 6<<

What compression options are you using when making the PDF? It could be introducing JPG artifacts…..
JS
John_Slate
Nov 20, 2003
If you create a file using the gradient tool from default black to default white that will yield as even a histogram as you can get.

Print that, and if you still see posterization, then the problem is with your workflow or printer.
KC
Kent_Chiarelli
Nov 21, 2003
I’ve printed a linear gray card and don’t have the problem. I guess what I’m asking is what are some telltale signs that the file might print poorly even with a good soft?

BTW, I usually do all my curves in 16bit and convert after major corrections are done.

Thanks guys. Now I’m fighting with the Ilford, can’t keep ink levels up in even brand new cartridges @#$!#*.
GH
Gernot_Hoffmann
Nov 21, 2003
Kent,

some operations lead to histograms with gaps, but this doesn´t cause posterization in prints. If we have enough pixels then the printed raster cell or the printed dot is the result of averaging several source image pixels, including the RGB-CMYK conversion, if the source is in RGB.

Posterization in prints happens for low gradients. On older printers this shows as a "plywood-effect".

a) the rendering depends strongly on the chosen dithering mode in the RIP.
E.g. Stochastic 720 dpi for an inkjet or Agfa Balanced Screen 1200dpi/106 Lpi
for a laser printer.
Unexpected results may happen if the dithering mode is changed or if a profile is used which was made for a different dithering mode.

b) In cases of problems it might help to dither the original RGB image. I have done this years ago for printing on a cheap HP inkjet.

Nowadays, the dithering by the RIP should be perfect (based on experiences with PosterShop Pro and Best ColorProof).
There must be something wrong in your workflow.

What means "ink levels" ? Do you create ink drops with different sizes ? Otherwise there are just two ink levels per ink – on or off (for an inkjet).

Best regards –Gernot Hoffmann
KC
Kent_Chiarelli
Nov 21, 2003
Thanks for the reply Gernot. The Ilford is a 600 dpi printer so we usually print at 600 Stochastic for best results, and haven’t changed it yet. We do CMYK conversion in "shop" and then TIFF. Those files are then checked again one last time before printing, and show no "plywood" on screen, although the printed effect is definitely plywood! We are using RipStar 5.5 which was an upgrade from an older version of Postershop. In your experience with postershop pro and Best Colorproof can you tell me if they work with Windows XP? We just upgraded the ripping PC but RipStar 5.5 doesn’t install on XP, having errors in the HASP drivers updating the registry. Still using Windows 2000

I will look into the RIP as the culprit now tho. Thanks again.
GH
Gernot_Hoffmann
Nov 21, 2003
Kent,

I´m using Win98 because of much "older" hardware (haha – just 4 to 5 years old). I don´t recommend PosterShop Pro by Onyx. The color conversions are good but the menues are terrible.
Finally (after some hundred hours testing and calibrating by PosterShop Profiler) the results are measurably good.

Onyx doesn´t offer anymore any help for the previous version 5.5 (which I have), and even the update (for this very odd program) is expensive.

I´m sure that Best programs will run with XP. These programs are recommended. <http://www.bestcolor.com>

Best ColorProof is a proofing program, not a simple RIP. There may be better alternatives by Best for "simple" printing.

The HASP driver problem is perhaps "marginal", hopefully.

Best regards –Gernot Hoffmann
KC
Kent_Chiarelli
Nov 22, 2003
OK… well after a little head banging, I was able to install and run RipStar 5.5 in XP, the supplied HASP driver won’t work with XP but the updated driver from Aladdin worked and allowed full install. I must say however, that even with a newer 2.6 PC w/512, RipStar uses up 100% processor time when printing… ripping uses about 60-70 but when printing starts it bops up to 50 percent and causes System to run 50%. Old software I guess.

In addition, I find that the "plywood" I was getting seems to be linked to Ripstar. When I installed it fresh, I didn’t linearize nor did I let it control GCR and the blacks were at least black and there was some density. I then did an ink restriction down to 270% and also checked the Smart GCR box. Next print I got I could see the black laying down and after all passes were made, everywhere the black was laid down there was plywood. SO, in effect, without a linearization done, letting the Rip control the black compensation causes wood. We don’t have a densitometer anymore so I can see doing this by eye will be tough and lengthy. Never done linearization before, but do I assume correctly that it will eliminate or greatly reduce wood? At this point, the only inks I seem to be using up are the mediums and yellow. No light or med black or much K at all. Haven’t seen much magenta or black being used in a full color print files.

I am interested in Best’s software, may have to look further into it, possibly find a demo if there is such a thing.

Can you recommend a fair priced densitometer? Ripstar makes no recommendation for compatible models with their software. At least Best recommends what to use with theirs.

Thanks again.

Kent
GH
Gernot_Hoffmann
Nov 22, 2003
Kent,

Prepress suppliers offer hand-held densitometers, but I prefer a computer controlled instrument: X-Rite "Digital Swatchbook".

Measures primarily spectra. Calculates by "ColorShop" color values in several color spaces, density, visual dotsize (the effective percentage of covered area), simulates colors for different illuminants and shows gamuts of monitors and printers by interpreting Icc-Profiles.
The instrument is fairly accurate for practical purposes. The tutorials are excellent.

Maybe GretagMacbeth has something similar.

Best regards –Gernot Hoffmann

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