how to convert rgb black in image to 100% black

[mazengh]

I have a lot of rgb images that contain black text (as a raster with colored images) and I would like to convert everything black to 100% K in cmyk mode. Is there a way to achieve this?

Thanks in advance.

 

[jay12345]

I have a lot of rgb images that contain black text (as a raster with colored images) and I would like to convert everything black to 100% K in cmyk mode. Is there a way to achieve this?

Thanks in advance.

I have recently purchased Alwans ink optimizer and have been playing around with it's ability to do this. As long as the text is still vector it can convert the rgb black to k. It's an awesome feature but it is a pretty costly product. If you wish you can pm me and I will run the files through it for you.

 

[DCurry]

Convert to CMYK using Maximum Black Generation. Here's a couple of threads that address this issue:

Fixing 4c Black Text in Flattened TIF Files

Retaining Blacks

 

[mazengh]

I have tried the maximum black generation fix. it works well but as stated in the previous thread it ruins colored areas on the image. they mention a way to overcome this by generating a mask but i don't understand how.

 

[Stephen Marsh]

I have tried the maximum black generation fix. it works well but as stated in the previous thread it ruins colored areas on the image. they mention a way to overcome this by generating a mask but i don't understand how.

Is the text "isolated" and or easy to select, or is sitting on top of the photo? Can you supply a crop of the image?


Stephen Marsh

 

[mazengh]

It's 200 books i have to scan and print. there are all different kinds of scenarios. so i was thinking maybe there's a way to convert using an icc profile that would convert all rgb blacks to 100% k

 

[Stephen Marsh]

It's 200 books i have to scan and print. there are all different kinds of scenarios. so i was thinking maybe there's a way to convert using an icc profile that would convert all rgb blacks to 100% k

How will you be printing these books - composite (digital) or separated (press)?

There is no magic answer or solution for scanning in 200 books with X amount of pages per book and automatically colour separating only the text elements differently than photographic elements...it is all pixels and the only difference in the pixels is the darkness.

Do the photographic elements or non text areas have a dark point similar to the text, or are they all lighter in tone? In other words, is the text the darkest element on the page?


Stephen Marsh

 

[mazengh]

It's all cartoonish drawings. No skin tones or color critical area but with the maximum black gcr the colors become way off. If I can convert all blacks to 100% k I should be ok even if there are darker black points than the text. I will be printing sheetfed offset.

 

[Stephen Marsh]

It's all cartoonish drawings. No skin tones or color critical area but with the maximum black gcr the colors become way off. If I can convert all blacks to 100% k I should be ok even if there are darker black points than the text. I will be printing sheetfed offset.

Will your scans have the darkest areas of text and linework as pure black 0r0g0b, or will they be more like 12r17g14b?

What CMYK space would you ideally be converting to? Fogra 39? GRACoL? SWOP?

I presume that you would like the cartoon and text elements to have 100K with no CMY tints under the K? EDIT: If these are scans of printed work, I presume that the colour comics have a halftone dot? if so, will you be de-screening these scans to avoid moire when you rescreen and output new separations to plate?

What version of Photoshop do you have (as this may take an action run in batch mode, over and above the base profile).

Can anybody reading this topic thread create and share a "proper" CMYK ICC profile that does a similar thing to the old legacy Custom CMYK method of Photoshop Max GCR (0cmyk whites, 100K only "four colour" blacks)?


Stephen Marsh

 

[mazengh]

not sure if the darkest areas of text and linework are pure black 0r0g0b or 12r17g14b. I will double check and update. Ideally I want to convert to a fogra39 based profile.

"I presume that you would like the cartoon and text elements to have 100K with no CMY tints under the K? EDIT: If these are scans of printed work, I presume that the colour comics have a halftone dot? if so, will you be de-screening these scans to avoid moire when you rescreen and output new separations to plate?"

correct...

I have photoshop cs 5.5

 

[mazengh]

It seems that the dark rgb spots my scanner achieved range from r0g0b0, r1g0b0, r0,g1,b0, r1g0b0, r1g1b0, r2,g1,b0... etc

 

[Stephen Marsh]

It seems that the dark rgb spots my scanner achieved range from r0g0b0, r1g0b0, r0,g1,b0, r1g0b0, r1g1b0, r2,g1,b0... etc

Excellent, that is dark and neutral enough for an action.

I will presume that the images are of a "traditional comic/cartoon" style effect with solid black keylines with colour fills. Is this a fair assumption? Or are the images more illustrative like a "graphic novel"?

Did you use a scanner descreen setting, or will you be using Photoshop to descreen?

I should have an action for you later today. As I am flying blind here I can't optimise the action steps for your unique scan content, however I hope that it will work well for you. Obviously test first to ensure that you are happy before you batch this on hundreds of images - and always work on dupes of the originals before descreening, colour conversion or other "destructive" steps.


Stephen Marsh

 

[michaelejahn]

Lightning Source and several other print service providers have 25 people scanning high contrast black and white books with line art, halftoned greyscale and full color books - processing them, and returning them to print ready PDF. Anyone doing this sort of work at any volume do not use Photoshop or PitStop.

Book processing it complex on its own, even when you have text only.

How are you capturing the pages ?

A few apps to look at are;

IoFlex - Industrial-Strength Software Solutions for the Printing and Publishing Industry

Ricoh: IoFlex

Atiz - Home of Book Digitization & Scanning Solutions

Otherwise, you will be spending a great deal of time in Photoshop for sure ! Since these files need to be scanned at 600 plus ppi, and in RGB ( or at least greyscale ) this is going be slow.

 

[michaelejahn]

It's 200 books i have to scan and print. there are all different kinds of scenarios. so i was thinking maybe there's a way to convert using an icc profile that would convert all rgb blacks to 100% k

I have direct experience with this and will tell you that there are all sorts of problems that can't be solved in Photoshop and using an ICC profile.

There are applications designed to handle these types of problems - I worked as a consultant to IoFlex, that is one application that can overcome these types of image processing hurdles.

https://docs.google.com/present/view?id=dfwf37zj_32g7t6npg8

Warning - Pricey.

If you are working with 600 / 900 pixel per in files ( which you need to reproduce type properly and descreen halftones ) this is a very slow go in Photoshop !

 

[Stephen Marsh]

I have attached a Ps5 colour separation action, however I am not 100% happy with it... so let me know how it goes with your scans.

I am presuming that you have descreened the images without degrading the linework.

I agree with Michael that this will be a slow process and that there are better ways to do this if you are after more productivity and optimal results. You will need to run the action in batch mode (automate batch or image processor) and most likely do this overnight. Of course, work on dupe files and test with a small batch that things will work correctly before unleashing the whole batch process.


Stephen Marsh

 

[michaelejahn]

The other issue you may need to contend with is page to page alignment. If the book was cut apart ( had the binding removed ) and then scanned - backing up front to back is not the only issue to contend with, there are issue of chapter stands and chapter ends.

When you are finished, you may NOT want the PDF to be a single image - for to large to re-print - ideally, the page elements are converted into the lowest bit depth that will support that part of the page - text and line art would be 1 bit , greyscale areas for black and white photos, RGB ( or CMYK ) for color images - if this is a comic book-like art, with large flat tints of color surrounded by black lines of varying width ( pen and ink-ish ) that might be better represented in a PDF as a colorized 8 bit TIFF.

Again, not sure, but these are issues you might need to consider.

 

[mazengh]

Thank you Stephen, I will test your ICC to see how well it performs.

Thanks Michael, I will contact IOFlex to test a demo and see how well it performs.

 

[michaelejahn]

@ mazengh - IoFlex does not really sell Book Maker 'direct' unless you are buying a lot of seats - they may sell BlackBox as a stand alone.

if you need contact details, email me privately - [email protected]

 

[RUsure]

If the text (or the majority of "verbage) is isolated, run two (2) black plates. One, the "images" that don't need to be whacked, plus, second, the text that's been "adjusted" . . .
Or, double-burn your plates . . .
Flexibility sometimes requires an analog solution . . .

 

[mazengh]

@ mazengh - IoFlex does not really sell Book Maker 'direct' unless you are buying a lot of seats - they may sell BlackBox as a stand alone.

if you need contact details, email me privately - [email protected]

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