RGB to CMYK (channels) with PixelConduit plugin

As I'm unable to submit a user tip yet, I thought I'd share my solution here for anyone looking to simulate CMYK channels in Motion/FCPX.
PROBLEM
For some reason you want to convert your RGB source clip to extract individual CMYK (Cyan, Mangenta, Yellow, blacK) channels. For example you'd want to simulate the printing process of a book on a printing press.
SOLUTION
Use a free FCPX/Motion 5 plugin caled PixelConduit, a node-based visual effects design system. Install the plugin before launching Motion.
To extract CMYK channels, I used a (linear) RGB to CMYK formula:
Black = Math.min( 1 - Red, 1 - Green, 1 - Blue )
Cyan = ( ( 1 - Red ) - Black ) / ( 1 - Black )
Magenta = ( ( 1 - Green ) - Black ) / ( 1 - Black )
Yellow = ( ( 1 - Blue ) - Black ) / ( 1 - Black )
and translated it to PixelConduit's nodes.
Clone your source clip four times. Call the clones 'Cyan', 'Magenta', 'Yellow' and 'Black'. Navigate to Library > Filters > Conduit Effect System, choose Conduit and apply it to each clone layer. In Inspector, click 'Show Conduit Editor' and assemble the following node tree for each layer:
K (black) layer:
C (cyan), M (magenta) and Y (yellow) layers are identical except the first channel selection:
So, for M and Y layers change the 'Separate RGBA' node to output the green and blue channel respectively. You can copy/paste the whole node tree between intances of the filter so you don't have to create everything again from scratch.
You should now have four layers outputting a simulation of C, M, Y and K channel in greyscale. If you'd like to present these channels in colour you'd need to add Colorize filter to each clone layer:
And finally, if you use Multiply Blend Mode for each clone layer group you'll get a pretty close colour composition to the original source clip! By fine-tuning colour values in Colorize filters and/or tone curves in Conduit you could probably get a perfect conversion.
Colour values used in Colorize filter:
Remap White To:
1, 1, 1 (all)
Remap Black To:
0, 0.61, 0.89 (cyan)
1, 0, 0.5 (magenta)
1, 0.95, 0 (yellow)
0, 0, 0 (black)
That's it! Hope it can help anyone :^)

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Shortcut for viewing the CMYK channel while only one or more of the color channels are selected?

Hi all,
I cannot believe I forgot this shortcut! I use it ALL the time.
When you have just one (or more) RGB or CMYK channels selected, and want to view the RGB or CMYK composite channel as you work with the individual channels, what is the keyboard shortcut for this?
(The problem is that it became so automatic because I use it so often and this morning when I was in Photoshop, I actually tried to think about this shortcut and found that I had forgotten it!! (Maybe I seriously need to eat more carrots!) I hadn't used it in the last few days, so that is a good excuse on my part, I hope .)
Thank you very much in advance for your help!
Christine

Okay...never mind! As soon as I wrote this post, I "clicked" that all I really needed to do was look at my PS keyboard shortcut list, which I did:)
It all came back to me straight away.... it is the ~ key.
Just a little Monday morning brain glitch!
Thanks all & have a great day!
Christine

Problem with color after converting RGB to CMYK

In RGB, I'm using #0000FF blue with some transparancy over a textured background. The result is a bright, textured blue. But when I convert to CMYK, the resulting blue is very dull. It improves somewhat if I changed the transparency to 0%, but then I lose the texture and it's still not as bright. Any help would be appreciated.
Here's some pictures to help understand:
RGB
CMYK

robr2 - there is generally speaking no way to print a blue color that is so saturated. When you convert to CMYK, Photoshop splits your bright saturated colours into only 4 inks. In the case of bright blue, what makes it a bright blue is mainly the fact that there is no yellow in it. The most saturated blue achievable in CMYK printing is right there, previewing loosely in front of your eyes.
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Color correct CMYK Image with RGB Image

1. anybody please tell me is it possible to perform color correction in CMYK image with RGB reference image
2. how to do that i mean what are the details i have to watch for?
ADVANCE THANKS

Your match using my color profile(similar to North American General Purpose) would be 29c 100m 83y 35k. Convert a sample swatch, using your color workflow/profile.
Some RGB colors won't convert well to cmyk (eg 0R 255B 0G). In that case your problem is not using a RGB reference image for CMYK color correction, but the cropped color gamut in the color conversion itself.
In those cases of saturated RGB colors you may have to do some handtoning to surrounding colors, to help create the illusion of RGB saturation to the troublesome color you are matching.

How to make a script to convert RGB to CMYK as black 100%?

Hi guy
my customer sent me a book (144 pages) for print but all of them are RGB and Tiff, she scan them. there are on the page some texts and pictures. The text are R=30 G=30 B=30.I think if I can make a script I will do it very soon to black 100%, but unfortunately I dont know anything to make script
anybody can help me ?anybody can make it for me ?

We need to know some more information.
1. The book consists of 144 pages, and each page is in fact an RGB image in TIFF format.
    Correct?
    That means, the text is already rasterized, but with low resolution (no more than 300ppi).
    A very bad starting point, in my humble opinion. For offset printing this is not acceptable.
2. Is the printing process offset printing or by digital printing?
Nevertheless we may think about a conversion of these images into CMYK K-only (one plate
per page) .
a) Increase contrast until R=G=B=0 for text.
b) Convert each image into Grayscale, using a so-called Black-Ink-Profile, for instance
    Black-Ink-ISOCoated-v2-eci (can be explained later)
c) Make empty CMYK image, here for ISOCoated-v2-eci, and paste the Grayscale into the
    K-channel. All further handling happens as CMYK file for the process ISOCoated-v2-eci.
    Void plates CMY don't matter.
    Post #12 here:
    Re: Colour shift (from CMYK = 0 0 0 20 to Grayscale K = 22 !)
All this can be done by an action (I hope so...).
Much better would be a new start by InDesign with typographical text (K-only vector instead of raster)
with images in RGB or CMYK, taking into account the intended process.
Note: Photoshop can deliver vector text, if exported as PDF.
Best regards --Gernot Hoffmann

Rich black when converting RGB to CMYK

I'm working in an older version of PhotoShop (7) but any help on the topic would definitely help.
My problem is that I am converting RGB native images to CMYK and my Key (Black) comes out rich, contains equal levels of CMY and K, instead of true black, only k.
Currently my way around this is to do the standard convert to profile CMYK and with my path selected to the section I would like to be true black simply turn off all CM and Y channels and re-save the image but this is a little labor intensive.
Is there a way that I can go straight from RGB to CMYK and achieve true black without alteration?

Yes, there is. You can use a CMYK setup or ICC CMYK profile that uses Maximum black generation. Unfortunately, that will almost always hose anything photographic in your image.
Is it typographical elements that are becoming four color? If so, then they should be done in a page layout program where they can be rasterized separately from the photographic image. If it is type you're worried about, is it large type or small? If you have to set large type in Ps, then it's probably fine to let it run four color.
If it were me and I had to do everything in Ps, I would probably make two conversions of the file to CMYK - one with a standard black generation and one with Max K. I would then select the black you want from the max K version and paste into the K channel of the "normal" document, and then use that as a selection to delete from the other three channels.
A third way is to do type in Ps and leave the type as a vector type layer, then save the file out as a Photoshop PDF, which is then placed in a layout app. or just sent to the printer through his RIP. That should work too, but there are too many places for things to wrong for my taste.

Mixing Pantone Colors - Just like CMYK channels???

Hey Everyone,
I just signed up to the forum and had a look around. Hello everyone and I'm glad forums like this are around!
So, my question is hopefully one that is possible. I've looked elsewhere but can't find any difinitive answer or perhaps I haven't worded the question right but here it goes...
What I'd like to do [in photoshop] is treat 4 pantone colors just like CMYK channels. What I mean by that is that I would like to replace Cyan, Magenta, Yellow and Black with my own colors [pantone colors] and have them mix and act exactly like those channels. As in, when I open a full color image, and my pantone [or any color] channels or color profile is active, the full color image will react to those colors [with the blending of the colors].
Instead of 45% Cyan, 55% Magenta, 83% Yellow, and 2% Black in a given spot, it would be a mix of the 4 chosen colors [example: 45% pantone A, 55% Pantone B, 83% Pantone C, 2% Pantone D].
or to put it another way, if I were to color the background in, say, a blue, I would be able to use the "Info" panel to see how much of each pantone color was mixed to create that color. Obviously there would be a limit to the colors I could create based on the pantone colors I select.
I don't want to do anything printing wise with this technique. I am looking at it solely as an onscreen viewer or perhaps use it in some manner for screen printing.
Anybody have any ideas on how to achieve this?
Many thanks in advance.

Beyond setting up a multichannel document there is no magic. And it is still merely an approximation because some colors can neither be simulated on-screen nor actually printed that way. That ultimately is the whole point - PS can't simulate anything that is impossibole in the "real world" and expressed as a color profile. Anyway, I have the feeling that you have a wrong understanding what spot colors actually are/ are meant for. They simply won't respond like the basic CMYK channels because their actual inks don't behave that way. Your ink percentages will never represent anything equivalent to a mathematical mixing formula as when using RGB or CMYK, instead they are the inks color multiplied by the opacity. In case of an on-screen simulation/ proof they would not even necessarily include effects that happen due to spectral absorption when light travels through the inks or the inks mixing chemically/ physically at the pigment level. It really doesn't exactly make sense for what you have possibly in mind due to the aforementioned specifics and limitations of the simulation. One could even go so far as to craft everything in red on screen and then swap the color for green during the printing process, assuming only 100% opacities are used. That is to say spot colors are often more considered like masks that constrain the actual ink to certian areas and when you think of it that way, you may begin to understand how and why your grand plan may fall apart. Of course we don't know what your artwork looks like, so it may work, after all, but I realyl think you are heading in the wrong direction, dreaming up something that doesn't exist.
Mylenium

Need Info on RGB to CMYK

Hi,
I am new to Illustrator (CS5) and not fully comfortable with RGB vs CMYK. For instance, I created a logo for use on the web using Document Color Mode: RGB where my background color in RGB is 0, 0, 130. When I create a Print document using Document Color Mode: CMYK and copy the logo into the print document, it converts that background color to CMYK (C:100, M:98, Y:16 K:18) where the RGB is now (44, 45, 111).
Is there a way to get a closer match to the original RGB color 0, 0, 130? When the specifications for the print advertisement says images must be in CMYK, I hope I am accomplishing this by using the Print Document Color Mode of CMYK vs RGB? I feel somewhat ignorant on utilizing the RGB vs CMYK color modes and if anyone can give me a tip on what techniques they use to get a closer match of colors for RGB to CMYK or vice versa, I would love to hear it.
Thank you,
Keith

Keith,
First, be aware that you have posted to the Photoshop forum, not the Illustrator forum. The general concepts of color and color management are the same across the spectrum of digital imaging. However, its implementation is slightly different from application to application, so you may also want to post your question to the Illlustrator forum.
[EDIT: Brain fart on my part... This is the color management forum, NOT the Photoshop forum, so you are in the right place! (I spend most of my time in the Photoshop forum; I lost track of where I was...)]
That said, you're running up against a general concept: color gamut.
The color you've spec'd in your RGB file (0/0/130 - and we'll assume for now that it's in the sRGB color space) is outside the gamut of every CMYK color space. That means that the RGB color you see can not be reproduced using a mix of the four CMYK process colors (cyan, magenta, yellow, black). When converting to CMYK, the software picks the closest color that is within the gamut of the CMYK space, hence the color shift.
When you're designing for CMYK, it's best to work in soft-proof mode which allows you to see a pretty close approximation of what your colors will look like in the final color output space - in your case, CMYK.
In Photoshop, to turn on soft-proof, go to View > Proof Setup> Custom... and choose the CMYK output space that matches the press conditions you are designing for.
There are books written about this, but hopefully this short answer points you in the right direction.
Message was edited by: Rick McCleary

How do I find out if a photo in iPhoto is RGB or CMYK color? How do I change from RGB to CMYK?

How do I find out if a photo in iPhoto is RGB or CMYK color? How do I change from RGB to CMYK?

Open the file with Preview, type Command + i to bring up the Info pane and it's color mode and profile will be listed as shown here:
To change the color mode to CMYK you'll need a 3rd party image editor like Photoshotp or GraphicConverter to do it. Why do you need CMYK?
OT

How can I convert Pdf from RGB to CMYK, keeping font color 100% K while working in Illustrator?

How can I convert Pdf from RGB to CMYK, keeping font color 100% K while working in Illustrator?
When I try to open the document in Illustrator and I convert to CMYK the black font converts to rich black, but to set up for Offset printintg I need the text to be only in Black (100%K).
The original source of the document is a Microsoft Word file, I have converted the Word file to Pdf in order to setup for OFfset Printing.
Thanks

I have tried that way, but the downside is that the fonts are set in gray not in a 100%K, also I have to deal with other fonts that are composites and meant to stay Full Color. I could select text by text and convert to gray but, its a 64 page document and I wouldn't want to make a expensive mistake.

Rgb to cmyk turns white brown

Hi Guys
In previous versions - changing from RGB to CMYK or vice versa would change the colours slightly but ever since CC when I change one to the other my white
goes brown and there is a yellow tone to the image.
Has anyone else experienced this - it's not slight either see image. I haven't adjusted anything - the original CMYK is on the left and
when I make it RGB - it goes brown.
Has anyone else had this issue?

I'd try a new display profile first. Recalibrate, or if you don't have a calibrator use sRGB (or Adobe RGB if your display is wide gamut).
Everything in Photoshop passes through the display profile. If there's a problem with the profile it can happen that one conversion goes bad but not another.
On Windows a common cause for this is bogus manufacturer profiles pushed through Windows Update. Mac isn't as susceptible to this, but there you have an added complication called ColorSync (which is where the actual profile conversions are done). So if a new profile doesn't fix it, you probably need someone with Mac OS X expertise.

RGB to CMYK gives me a white glaze? how to get rid of it

In photoshop cs5 when i convert an image i am working on from RGB to CMYK i get a white glaze over the image? as if i have added a photo filter or something? do you know how to prevent this on a mac computer?

Apple Custard Studios wrote:
…yes i can see that it is broke, but if you look in your last post the before image is in there for some reason, and the after picture is at the top in the earlier discussions.
Sorry, I don't understand what you're trying to say here. How can the "before" image be in any post of mine if I have never been able to see it?
The image I posted in my post, was your "after" image CORRECTED by me as explained in that post:
"Converting it to sRGB and setting the black and white points via a quick Auto Levels adjustment, brings about an improvement."
In other words, I downloaded your "after" image, opened in Photoshop, went to the Edit menu and used Convert To Profile to convert it to the sRGB color space, then I ran and Auto Levels adjustment. That's how I fixed your mess.
Apple Custard Studios wrote:
Hi station_two
…When i convert from rgb to cmyk, i SIMPLY GO: Image > mode> then click cmyk?…
Geebus Chrysler! No, that is indeed not just "primitive" but totally wrong. Go to the CONVERT TO PROFILE menu item in the Edit menu in Photoshop, and from that menu select the specific CMYK profile you want (or your printer requests). Be careful to select CONVERT TO PROFILE, do not under any circumstances choose "Assign Profile"! Converting to the appropriate CMYK profile will also automatically change the image mode to CMYK mode.
Apple Custard Studios wrote:
…which i am unsure it it may mean i have wrong profiles set, but if so what would i need to change it to?…
Apple Custard, it's obvious that you have no clue as to what Color Management is, and teaching you Color Management step by step here exceeds the scope of what can be accomplished in a forum. A good place to start reading up on it is here:
http://www.gballard.net/psd/cmstheory.html
In a nutshell: Your Monitor profile should be the file resulting from your calibrating and profiling your monitor with a hardware calibrator puck. Calibrate and profile your monitor regularly and often. Your monitor profile thus will be device-dependent, specific to your monitor.
Your working space, on the other hand, should be a device-independent profile, such as Adobe RGB or sRGB. It should NEVER, ever be your monitor profile.
Your target profile when printing should be device-dependent and specific to the combination of ink, paper and printer model you'll be using. For the web, create a copy of your image file and convert it to sRGB, then save it as a JPEG as needed.
Good luck!

RGB to CMYK to commercial printer

We are using CS2 InDesign and Photoshop 7 on a PC. I am putting together two
large books. One insert section of the first book has color photos. I have
to prepare these color photos for a printer located in China. They want all
images to be CMYK .tiff.
I have an assortment of about 100 images from various sources around the
world, there are .tif, .jpg. .bmp, and .psd. All of them appear to be RGB.
There are images with: 1) no color profile, 2) sRGB IE60966-2.1, and Adobe
RGB 1998. Do all images need to have the same RGB color profile before
converting to CMYK?
I have been converting all of these to .tif (and using a single dpi/pixel
resolution for
all images).
Do I just select/save as color mode CMYK? Or are there special
settings/profiles I need to know about. Is there anything special for China?
The printer's English is not that clear . I was hoping that someone in this
group would be familiar with RGB to CMYK conversion.
Also, it appears that the final PDF pages (with embedded Tiff images) will
be very large. The first complete book for this project (there are two
books) looks like it will be about 20GB. The second book looks like it could
be 12GB. Both books together equal about 1,000 pages and have about 1,000
images. 90% of the images are grayscale. What are the current technologies
for sending large projects like this to a printer?
Thanks
ps, the Photoshop group suggested that I write to this group.

Tech....
In the conversions, are you referring to conversions of B&W or color images? I'll assume color for the moment.
Assuming your monitor is properly calibrated, and assuming you are viewing your color images on your monitor, your conversions should keep "in gamut" colors the same. You will, however, probably see some loss of dynamic range, color, and saturation as you enter CMYK. If the color and dynamic range of the original is all within the destination CMYK gamut, you should see very little, if any, shift. The sad fact is that CMYK on press has limited dynamic range and color, especially compared to a bright monitor. This is generally true, though CMYK can print some colors that lie outside the typical monitor's gamut.
If you have a brightly colored original in RGB mode, then you should experiment with both perceptual and relative colorimetric rendering to see which one looks best. This is an image by image thing. Relative colorimetric will reproduce all "in gamut colors" as accurately as possible, then will take out of gamut colors and bring them to the closest printable color. This can cause loss of detail and 'piling up of colors' as you near the boundaries of the image's color gamut in the destination CMYK space. Perceptual scales ALL colors and preserves the relationships between colors, which sacrifices color accuracy and saturation, but sometimes looks more natural, especially if there are a LOT of out of gamut colors. Pick whichever ones looks best overall.
Then, once in CMYK, make minor curves adjustments to tweak if for CMYK. Just be careful not to push it too far, especially in the deep shadows, since you may push beyond the ink limit of the press. For example, if you convert to US Web Coated SWOP v2, the ink limits are set at 300 total. If you drastically darken the shadow areas, you could end up with an ink limit of 320, 330, 350, etc. Knowing the ink limit of the press will help you stay within those limits. Final tweaking in CMYK is usually a good thing.
How did you determine that the images were dull with too much magenta? Did you print a proof on a calibrated printer, or is this just your screen display? Or is this from a printed image off the press? I have a well calibrated monitor and accurate custom profiles for my inkjet. If I am sending a job to a press that supposedly prints to US Web Coated SWOP, I can proof that file on my inkjet and get a very good match. We need more information to know exactly what you are doing and how you are assessing your images.
Normally, I do the conversion in Photoshop, using the rendering intent that looks best. Then I tweak the image in CMYK to get it looking its best. I usually have the press profile, but sometimes work with a standard profile if no custom profile is available. I leave the image tagged with my conversion profile. Then, I usually place these images into InDesign, with the profile intact (color management turned on in InDesign). I right click on the placed image to be sure that the profile and rendering intent are set to what I want. Then, I can either supply the InDesign file to the printer, or convert to PDF (leave color unchanged) and make sure that all profiles are included. InDesign should export each image to the PDF properly, along with profile and intent. I have never sent to job to press using Photoshop...only InDesign or Illustrator.
BTW, rendering intent is only used when getting an image from one color space to another, such as a conversion from RGB to CMYK. You do that, choosing the one that looks the best. Once it is in the destination CMYK space, rendering intent is no longer needed, since all the colors and tones have already been remapped into the final space. Rendering intent is just used to help us handle those out of gamut colors.
Hope this helps.
Lou

How can you tell if a PDF is RGB or CMYK?

From the screeshto below I am finding the only way to tell if a PDF I receive is RGB or CMYK, is by the transparency blending space. Are there any other ways?
The drop shadow on the chip is showing cyan, along with the yellow arrow. The original files do not have cyan in these areas. Is this because the PDF is being saved as smallest file size, which converts CMYK to RGB, then in Acrobat we are coverting RGB values back to CMYK, and with those color conversions you cannot proof Smllest file size PDFs for CMYK breakdowns.
What are others using out there in proffing PDFs for color, smallest file size with color conversion set to no? Doing that makes our PDFs about 150% to 200% larger and they often wont fit in email then. Are there any secret ways of proofing a standard smallest file size PDFs for accurate CMYK breakdowns?

In Acrobat Pro 9:
Advanced Menu to Preflight
Upper Right corner of Preflight dialog box click on "Options"
then select "Create Inventory"
deselect everything except colors and click "OK"
it will analyze your document and return with the number of "plates" as well as the names of the plates...

How to get rid of CMYK channels after making spot channels

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RGB to CMYK (channels) with PixelConduit plugin

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