Rich Blacks to Pure Black

[pdan]

I've been corresponding with someone met via forums similair to this one and have gone beyond my expertise. Effectivly it started as a band-aid approach to where -
The person assembles a larger (book) document from supplied (pdf) files. The normal scenerio applies. Some files are poorly constructed and contain (various) rich blacks not effectively registered on press.

Rich Black Type
Rich Black Objects
Rich Black Images

With only Acrobat Pro available I wrote (a) Preflight Fixup(s) which
Find Objects where the source color is 60,60,60,60 with a varience of up to 40
Convert such to 0,0,0,100

(I noted that the user need keep a creful eye out for elements intended to be darks blues, browns, etc)

This works for images and type, but I cannot create such a fixup for images.

What is the best method for this scenerio -
Enfocus Pitstop?
or a function of the RIP?

I think the end product is produced newsprint/web.

 

[alu]

After performing your first fixup.. would not the standard "convert to grayscale" pdf fixup work for the images (and should leave your other pure black items untouched) ?

 

[Stephen Marsh]

I am presuming that the original image is both colour and black? Why can’t a “traditional” separation be used (is the content similar to a comic illustration or a screen capture)? One can favour a stronger K generation in the GCR and still have a rich black, as K only shadows for photographic content is generally less than ideal.

A heavy or max GCR style ICC profile could be used if less CMY and more K is required.

The original image in the PDF can be opened in Photoshop and edited, then updated back into the original PDF using Acrobat Pro.

With the right tools, a special purpose profile or even better a devicelink profile could be created (PitStop Pro could be used to run the devicelink profile).


Stephen Marsh

 

[mattbeals]

Convert everything (images alone) to RGB then back to CMYK using perceptual using acrobat pro using the two black options.

 

[pdan]

@alu - the files are intended to print color.

@Stephen Marsh - I'm very un-schooled in the area of GCR/UCR. I suggested to the person I'm communicating with to look up the idea's of GCR and RIP-side software.
Gordo's recent post is very interesting stuff but I cut my teath in the "pleasing color" unmanaged 3302 world (and now merely operate a bizhub).

@mattbeals - Are these Acrobat default Profiles or Fixup's. Sounds simple, but I don't see options for convert to... The first file is already rgb.

I'll try to attach a ss

In the example, we have effectively one picture. Supplied pdf was created with PS. No control is available for received works.
Editing the large blaack areas is possible with PS, but obviously to tedious for the "type" areas.

Again, the objective is to create workable blacks for an envrionment (newsprint) where close register is not expected.

 

[Stephen Marsh]

Content that is obviously vector should not be supplied as raster (I’ll get off my soapbox now). The sample image was probably setup by somebody at the theatre company that does not understand newsprint (or any press) reproduction. The resolution of the raster file is probably too low as well.

Converting RGB photos to CMYK is one thing, converting graphical elements such as logos, text and “art” is something else.

If the RGB ads are supplied as images and they contain content that should be both raster and vector, chances are they are not supplied as PSD/TIFF/PDF using vector text layers set to multiply blend mode.

Presuming that the RGB black elements in the Photoshop art are not setup as layers in multiply blend mode and that a Max. GCR separation is used… There will be no underlying CMY tones, so one may need to introduce trapping in the Photoshop art to account for mis-registration. Sadly, web printed newspapers often have huge mis-registration issues.

Even converting to a Max. GCR style profile will not cure all the possible issues with such content. Going to a Max. GCR style conversion will just trade off one set of problems for another.

Ideally, there would not be any holes in the CMY under the fine K text elements (black overprinting) - however if the job was supplied as a flattened RGB image with no multiply layers for the black content, then these ads would need manual retouching in CMYK to fix them up for best possible reproduction. For many reasons, this will probably not happen.


Stephen Marsh

 

[mattbeals]

@alu - the files are intended to print color.

@Stephen Marsh - I'm very un-schooled in the area of GCR/UCR. I suggested to the person I'm communicating with to look up the idea's of GCR and RIP-side software.
Gordo's recent post is very interesting stuff but I cut my teath in the "pleasing color" unmanaged 3302 world (and now merely operate a bizhub).

@mattbeals - Are these Acrobat default Profiles or Fixup's. Sounds simple, but I don't see options for convert to... The first file is already rgb.

I'll try to attach a ss

In the example, we have effectively one picture. Supplied pdf was created with PS. No control is available for received works.
Editing the large blaack areas is possible with PS, but obviously to tedious for the "type" areas.

Again, the objective is to create workable blacks for an envrionment (newsprint) where close register is not expected.

This isn't the actual file I hope. Send me the PDF .

 

[pdan]

@Stephen Marsh - ok, so my ignorance of PS and GCR is not the hurdle here. A global replacement of cmy to k is pretty difficult if not impossible to achieve.

@mattbeals - yep, actual art file as received - as I prefaced, this is not a perfect world. That file is an actual file and is representative of what any full rasterization will result as; Word Art, PS export, the possibilities are large.

I am not opposed to the "teach them or charge them" philosophies of the industry. Just plodding along in an area not uncommon.

Stephan hit upon the point I was indicating - web-print newsprint is not geared towards (any normal acceptable) registration.
My apologies if I offend the sector. I expect their has been advances in such, but "it is what it is".

fwiw, the effective resolution for it's file size eyeballs out as "run it".

@Matt Beals - How do I send private message?, I'll check the forum tools.

 

[mattbeals]

matt )at( mattbeals.com

 

[pdan]

pm sent via forum tools Matt. Thank you, reply as appropriate.

 

[Stephen Marsh]

@Stephen Marsh - ok, so my ignorance of PS and GCR is not the hurdle here. A global replacement of cmy to k is pretty difficult if not impossible to achieve.

Newsprint on large high speed web presses makes rego hard, it is a fact of life. I used to supply weekly display ads to a local newspaper back in the day. I tried UCR/Light GCR, Medium GCR, Heavy GCR and Max GCR. Variation throughout one print run was bad enough, let alone week to week. If one looked at 10 different copies of the paper, the display add showed different registration, some good some bad. So it was very hard to find an “acceptable standard” to use. I settled on a heavy GCR approach where most of the gray component was made of K with lesser CMY. There are pros/cons and trade offs between different GCR methods, there is no magic answer.

Creating a separation that is K only for solid blacks and neutrals may at first seem like a good approach, however there are still pros/cons. The solid K areas will not be very dense, they really need CMY under them to boost density (usually working within the 210-230% total ink limit of web newsprint). Neutral grey tones that are not solid that are K only may require trapping of colour elements that adjoin these areas, otherwise a white gap will appear if rego is off. Due to the large amount of possible movement in newsprint rego, the trap thickness is can be very large, which is quite visible. So having K only neutrals solves some problems and creates other problems.

I would recommend a Heavy GCR newsprint separation approach, or perhaps Max GCR. Many newspapers may often respearate incoming work anyway, so whatever you do in external prepress supply may be changed anyway, whether you like it or not. If working internally, then there is of course more control.

fwiw, the effective resolution for it’s file size eyeballs out as “run it".

You mentioned that PDF ads were supplied created in Photoshop. The sample screen capture showed a job that should have been created as vector, not raster - there was a large amount of small type. As vector elements such as type are rendered at resolutions 1200dpi or higher, a 200-300ppi file that has raster type will be visually poorer. Effective resolution for type is different than effective resolution for newsprint halftones. Now, I am only guessing that the Photoshop PDF raster ads are flattened, they could be supplied with vector content layers for all I know. I can only guess by past experience.


Stephen Marsh