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

Similar Messages

Color Settings CS3 Mac for CMYK Commercial Print

Can somebody advise me as too what I should be setting my color settings to so they will be the same across the suite and when I send my files to commercial print that prints CMYK sheet fed coated.
I've read so much I'm confused. I'm new to CS3 and the Mac ... In the past my work has come back perfect in color and matched to my monitor. Now on CS3 on the Mac I'm not sure what to do.
If anyone can help it would be most appreciated.

Charlene wrote:
> Marco ... I read your post on rGB / CMYK conversion
Which one was that, if you could remind me?
>I work through a print broker that prints CMYK and the only thing he can tell me is that they print CMYK and on sheet fed coated.
Well, yes, print is always CMYK. As for "sheetfed coated", I would assume that they intend a color space like the one described by the U.S. Sheetfed Coated v2 profile (though it could possibly be the GRACoL2006_Coated1v2 profile). You may want to ask them to confirm one or the other, to be safer.
>So my question is di turn everything to CMYK on my monitor and change to sheet fed coated in the settings?
To make sure I understand your question, I think you are asking me whether you should turn your image file(s) to a chosen CMYK output profile. Yes and no. You should do your color and tonal correction work
b in RGB
, and convert to the intended CMYK output profile
b only as a last step
, just before you deliver the files to the print provider or the prepress specialists.
Do
b not
convert your files to the intended CMYK output profile in the beginning and correct them in CMYK. Do not do that. That is not the most desirable way to work.
The default working spaces in Photoshop's Color Settings are important, but not essential. Yes, you should set the default RGB profile to AdobeRGB (if not ProPhoto RGB, though you may wish to hold off on that one until you have more experience with the application), and the CMYK default profile to U.S. Sheetfed Coated v2.
But, as long as your chosen color management policies are to "Preserve Embedded Profiles", and as long as the image files you work on are tagged with the appropriate profile, then the default profile in Color Settings is no longer relevant.

Converting RGB to CMYK for printing.

So I went in to the Apple Store yesterday and told the guy that I'd like to design my own DVD cover for a presentation reel. I was about to spring for the teacher's edition of Photoshop, but he convinced me to buy the cheaper one with a Bamboo tablet...which was the same price as buying the program but included the tablet.
Hours later after designing my DVD cover, I find out that elements doesn't use CMYK mode. Ridiculous! This is my first time doing something like this so I wasn't entirely sure how to proceed... I thought.. oh well maybe I just switch modes later and I'm good. I guess this program was designed for less intense designers that print from a desktop at home, but I had other plans from the start. Anyways, what would you do? Here are my questions:
Should I take back the program/tablet and exchange it for one with CMYK capabilities? If I do this, will the document that I've used in elements be able to work in CMYK mode so I can send it to a printer? ...or do I make a really good print to a desktop printer and then just duplicate those for my cover?
Thanks for the help.

I came across a great web site where you can perform free RGB to CMYK conversions on your image files (up to 5mb). They offer a choice of numerous CMYK profiles. For U.S. commercial offset printing of your DVD cover, I'd recommend choosing GRACoL2006_Coated1v2.icc
http://www.rgb2cmyk.org/

RGB or CMYK colour formatting for iPhoto Albums printing.

Hi.
I'm putting my first iPhoto Album together. Info given from Apple about what colour format to use for your photos, says to use RGB. While this is corrcet for digital monitors and screens. Mass printing uses CMYK. Any images supplied to a printers in RGB will colour shift when printed in CMYK. No matter what a printer tells you, these colour shifts can be very noticable. I'm an Advertsing Art Director and I've seen the shift that happens.
I will be checking/colour correting all photos submitted to the iPhoto Album with Adobe Photoshop. And many will very probably undergo some corrections. Be it through levels, curves, hue/saturation, etc. Nothing to anything near an excessive level, but enough to make obvious improvements.
So I will then be faced with the choice of whether to save the images out in RGB or CMYK.
Can someone with some technique knowledge, from the iPhoto team, tell me/reasure me why RGB has been specified? And if CMYK wouldn't actually be a preferable colour format to supply in, considering you'll be printing them in CMYK.
Many Thanks, Jim.

You're absolutely correct. I was referring to notes make a number of years ago in regards to iPhoto 5 and that RGB was recommended for both books and prints.
I was confusing CMYK with Grayscale with Dot Gain 20% profile when stating iPhoto didn't support it which it didn't fully support until iPhoto 9.
In fact I just ran a test with iPhoto 6, 7 and 8 with a CMYK AND GrayScale files with the following results:
iPhoto 6 (06): wouldn't import CMYK but did GrayScale. The grayscale file would only display as a black thumbnail and negative full image. If the DotGain 20% profile was stipped from it the iamge would dispaly normally.
iPhoto 7 (08): wouldn't import CMYK but did GrayScale. The grayscale file would only display as a black thumbnail and negative full image. If the DotGain 20% profile was stipped from it the iamge would dispaly normally.
iPhoto 8 (09): neither file would import which is surprising:
iPhoto 9.2.3 (11): both imported and viewed normally.
iPhoto 9.4 (11): both imported and viewed normally.
In Oct, 2007 I got an email from Apple support with the following:
Also as iphoto makes a pdf of the book and then uploads it to keep the size down, it doesn't matter if the pics are RGB or CMYK as a pdf is a closed file. But since it is going through prinergy it has an RGB checker so this most be switched off. It is how the software in prinergy handle's it that causes the washed out affect as it takes the Red Green Blue colours and tries to convert to Cyan Magenta Yellow Black. Now the colour spectrum in printing between rgb and cmyk is quite different looking at a colour wheel will show you. The best way i can describe it is if you have a pantone book which has spot on one side and process on the other you can see a colour difference. Or if you use quark open up the colours and again switch between process and spot.
BUT ONLY CONVERT PICS TO CMYK IF YOU ONLY INTEND TO ORDER BOOKS. IF YOU INTEND TO ORDER PRINTS IT WILL NEED TO BE RGB.
Here's how i see it:
1. Apple doesn't want 2 different versions of the pics floating about as running CMYK through a photomachine (as prints you would order in the high street) will not print correctly.
2. RGb's going through a CMYK press using prinergy will attempt to convert and produce the washed out effect, or yellowing effect BUT will still print.
So it will use the 2nd option as it will still produce prints normally and books with a slightly washed out effect. Now to most people in the high street, who will notice a difference?
I have just received my latest book saved as CMYK pics in tiff format and no washed out effect. What i will say is The quality if still not as good as a print. Now we use a docucolour 5252 at work and the colour quality is better. I wonder how often the machine is calibrated and what colour curve it is set to?
However, I am unable to import a CMYK file in any iPhoto version until iPhoto 9. Go figure.
Thanks for the feedback. Hadn't addressed this particular subject in quite a long time.

Is the win 8 driver for the printer photosmart D7360 rgb or CMYK?

Hi,
I will be using Lightroom 4.2 (under win 8 64) and will have the monitor and printer (HP Photosmart D7360) calibrated by a colormunki photo.
When the printer profile is generated by colormunki, depening on the actual printer driver, they will be either a RGB or CMYK profile. Apparently, LR 4.2 will only show printer profiles to use if the driver of the printer is RGB . So if it was CMYK, I wouldn't be able to use the profile for printing in LR.
Can anyone please tell me if this printer driver is RGB or CMYK?!
Any help will be greatly appreciated!
Regards,
This question was solved.
View Solution.

The driver expects RGB data. The actual color inks in the printer use CMYK but that is handled by the driver, the applications need to send RGB data to the driver.
Bob Headrick, HP Expert
I am not an employee of HP, I am a volunteer posting here on my own time.
If your problem is solved please click the "Accept as Solution" button ------------V
If my answer was helpful please click the "Thumbs Up" to say "Thank You"--V

When printing a photobook does Apple convert the images from RGB to CMYK?

I'm a little confused by Apple's Photobooks. Most printers require all images to be in the CMYK colourspace, since the inks used are always CMYK. Yet Apple requires Photobook images to be jpegs in the RGB colourspace. Does this mean Apple's printers (presumably plural, since they are all over the world) do some sort of autoconversion RGB to CMYK? Surely this would result in a major downgrading of quality? I've seen a few non-Apple photobooks printed with unconverted RGB images, and they look dreadful - overblown red and yellows, with awful colour casts. I've not seen an Apple Photobook myself, presumably the colours are realistic?
Comments anyone?

Quote from the Reference:
Linear Light
Burns or dodges the colors by decreasing or increasing the brightness, depending on the blend color. If the blend color (light source) is lighter than 50% gray, the image is lightened by increasing the brightness. If the blend color is darker than 50% gray, the image is darkened by decreasing the brightness.
Now consider the values that a neutral medium grey would have in the RGB and the CMYK spaces you use.

Converting to .jpg to print (RGB vs.CMYK)

Hi all,
I am fairly new to adobe and all things it has to offer. I am slowly learning how to do everything myself. I am currently using CS6. I made myself a 16x20" poster in Illustrator, converted it to a .jpg using the export menu. I put it to my flash drive and printed it out at a local fed ex office. When converting it to jpg, I kept it in CMYK color mode, and set it to be at the highest resolution and the highest quality file I could have.
Now, I made another poster for a friend and did the exact same thing. Instead of taking her .jpg somewhere to get printed, she is trying to upload it to a photo printing site (walmart, snapfish, shutterfly) to get it printed and mailed to her. Her poster keeps getting errors on the photo uploading site saying it is corrupted and not a valid file type. I was confused, so I tried messing around with the illustrator file a bit, I ended up changing the color mode to RGB when I converted it to a jpg (I still made the artwork in CMYK mode). This uploaded fine to all the photo sharing sites, and was also half the size of the original .jpg (12 MB vs. 24). So then I googled it, and came across a website that says printers only print in CMYK. So if that is the case, what will happen when she prints this poster? And why won't these photo uploading sites allow me to upload a poster that is in CMYK mode? If printers only print in CMYK, you would think it wouldn't be a problem.
On a side note, when I try to upload the CMYK .jpg image to Fed Ex office online, it perfectly uploads. So maybe this is just a problem with simple photo uploading sites?
Thanks for the help! Again, I am fairly new to illustrator so I don't understand color modes much or much else.

I suggest you get your hands on Adobe's Print Publishing Guide. I am sure there are many online "photo" print services out there. The key is they are "photographic" printers which are RGB based. It wouldn't surprise me if they incorprated some type of default rejection coordinance where they reject CMYK files. You should be looking at PDF instead of JPEG anyway. And, since that is a large format print job, a medium resolution based PDF is adequate and small enough to send FTP. The advantage to PDF is it can honor a well established color workflow. Focus on reading the various RGB color spaces and the different levels of PDF. Also, spend some time on color management and converting from RGB to CMYK. I'd be interested in learning which color settings and workspace profiles you have in place.

Texture filter in Rgb mode to cmyk - safe for print job?

I want to apply the texture filter to a photo for a print job but the texture filter only works in rgb. Can the rgb file be SAFELY converted to cmyk for print?

In what way do you think a conversion from RGB to CMYK after the application of the filter will not be safe? What do you expect to go wrong?
...or if you have tried it, what has gone wrong?

Color assistance needed for commercial printer

Hi there,
We're a board game publisher about to send our first game to an overseas manufacturer. The game is composed of hundreds of cards with detailed, fantasy art, and we're excited to get this game finally out the door.
We sent the raw, packaged indesign (CS6) files to a local printer to see how everything would look before we have 3,000 copies of the game made overseas. The local printer used the same process that the overseas printer will, a 4 color high-end printer that is certainly impressive to people new to the industry such as ourselves. The sample cards they printed came out with fantastic clarity, but the colors are very muted. It's not a subtle change in color like I might see when toggling RGB to CMYK in photoshop for example. Instead, the colors on the print out look like someone slid a color saturation slider on the entire indesign file down by 25%.
When we print on our low-end inket at the office, the resolution is obviously poor, but the colors look great and match our calibrated monitors. When we export to PDF using "Press Quality", everything looks perfect on multiple computers here and at other locations away from the office. It's only the most important step, printing on a full-blown, commercial printer that the colors look so muted.
Here are some crude photos I took on my phone to help show the difference.
These photos have our office, inkjet printer cards are more colorful and the high-quality commercial printer cards are muted (sorry for the strange alignment, this forum is rotating the images for some reason):
http://www.watchtowergames.com/wp-content/uploads/2014/02/photo-1.jpg
http://www.watchtowergames.com/wp-content/uploads/2014/02/photo-2.jpg
http://www.watchtowergames.com/wp-content/uploads/2014/02/photo-3.jpg
Different cards here:
http://www.watchtowergames.com/wp-content/uploads/2014/02/photo-1b.jpg
http://www.watchtowergames.com/wp-content/uploads/2014/02/photo-2b.jpg
I've researched about swatches and color profiles, but all my experimenting hasn't produced any difference on my end. Therein lies the challenge, as I cannot duplicate the problem here at the office. The colors look great in indesign, great in exported PDFs, and great on our inkjet printed cards. Only when we pay a decent amount of money to the local commercial printer do we get these muted colors in our samples. And the local printer says their setup is exactly the same as our overseas manufacturer, which is terrifying. We've spent 17 months agonizing over all the details of the look of our cards for aesthetic purposes and game play so that players can quickly identify each card type by color. These muted colors will really mess the game up. We're pulling our hair out over here.
The local printer has offered to provide a color correction service for us, but at $100 an hour, that sounds like a lot for a new business like ours.
Is there some setting inside indesign that we are missing? Is there a way to replicate the muted colors on our end so we can at least troubleshoot this? Is there a method to turn up the saturation, if you will, for 4 color printing? Should we bite the bullet and pay the local printer an arm and a leg to color correct this? Any help would be greatly appreciated.
Thank you,
Tom
P.S. Also, if it helps, when we had the local printer digitally print a sample, everything looked far too dark, which they said was a side effect of the digital print process.

Thanks for the response, Rob.
We talked with a local printer as they assured us that their setup was the same standard that the overseas printer uses. They said the sample sheet they printed for us had marks on the edges. Supposedly, once we had everything matching up right with the local printer, we could mail the printed sheet here to the overseas printer and their system would put in the sheet with its colors on the edges and know exactly what we wanted. Heck, if I know. I'm picking this up as I go along.
By your post, it sounds like we have introduced an unnecessary variable (this local printer) and should just cut them out of the process and deal directly with the overseas printer. The challenge is that the next step is for them to make a sample game for us, and at $1,000 a sample game, it's going to get crazy expensive if we have to go through several samples. I'll see if they can just run a single sheet of cards as a test run like you suggested.
If the overseas printer sheet or sample game comes up with the muted color problem still, what steps happen next. I ask because I'm used to solving the issues and don't understand how to solve this one if it comes up again. Do I just tell them to "make it more vibrant" and they work their magic as professional printers, or is the expectation that I'm to go through each of our many illustrations and graphic designs and over-saturate them myself? I suppose we can cross that bridge when we get to it. It's just hard to work for 18 months on this game getting everything just right and now see this color issue that is out my hands that I cannot solve.
For color space, I think I understand you. Most of our art is RGB.Our Proof Setup is "CMYK - US SWOP v2".
Thanks again for the information.
Tom

IDcs2 late binding RGB to CMYK

InDesign CS2 uses two document profiles, RGB & CMYK. I have been using a "late binding" workflow with an Epson R1800 "RGB" printer, letting InDesign convert to the Printer Profile.
I was surprised I cannot use the RGB document space and let ID Determine Colors for the CMYK Printer Profile for a Phaser CMYK solid ink printer.
For CMYK printers are my placed sRGB images converted to the CMYK working space of the InDesign file for output, or are they just passed through so I can still allow ID to Determine Colors for Printer Profile selected ?
Does the same hold true for separations made to film or plates?
Thanks, Mark
Mac OS 10.4

Mark,
First, I work on a PC, so there may be some differences. I have sporadically had problems getting accurate color from IDCS2 when outputting to an RGB printer. I'm not sure why it happens, and nobody (including Adobe) has managed to explain what happens with RGB files sent to RGB devices. So, for that reason alone, I do not recommend using late binding workflows. I think it is an Adobe print engine issue, but they'd deny it no doubt, as they usually do. When the couldn't solve the problem, they just became "unavailable". In theory, when printing from IDCS2, the ID print engine will convert ALL document colors to your intended print space.
If my final intent is a press or other CMYK based device, I always place CMYK images into ID. I soft proof my final output space while editing in Photoshop, which I trust a lot more than I do ID. By the way, I have not had any problem with CMYK files rendering incorrectly, so that seems to work fine.
I don't have ID open right now, so I cannot answer some of your specific questions. For proofing on an RGB inkjet device, here is what I do.
1. Create the entire document in the destination CMYK space, including all placed images. Make sure the ID document itself is set to the same CMYK workspace, and make sure the document blend space is set to CMYK.
2. For proofing on an RGB inkjet, I first export to PDF, leaving color unchanged. Then I open the PDF in Acrobat and set up my print stream to have the correct printer profiles, etc.
3. I usually send both the IDCS2 file and the PDF to my commercial printer. This way they have both, just in case there is an issue with the IDCS2 file. And I ALWAYS have them generate a color proof on their inkjet as a contract proof. I like to compare it to my inkjet proof to make sure everything is right.
I hope this helps somewhat, though it doesn't take you in the exact direction you intended. I think Adobe still has work to do on their program, but perhaps this has been fixed in later releases of ID.
Lou

Colour mode rgb to cmyk

hello forumers.
id like to know if i download an image from the web which is rgb,can i convert the image to cmyk for no one to notice it was initialy taken from the net?
the reason im asking is because my teacher told us not to take any image from the net,(so we take photographs our selves).and if we do take an image from the net,he will know just by looking at it.
is this true?how can i convert if possible tell me please.
thank you.

I agree with Chris, and others - a good assignment should have several elements to it, and learning each, is what one should strive for.
A lesson might seem simple, like RGB Color Mode to CMYK Color Mode, but will likely have additional aspects, like dealing with a commercial printer, and working with their specified attributes for CMYK.
Same could be said for a lesson on isolating elements in an Image. One could buy a stock Image, with an Alpha Channel, but that would bypass learning how to create that Alpha Channel, and in life, not all Images come with Alpha Channels, or at least the one(s), that one might need/want.
A good instructor will structure a lesson with many parts, leading to the end result.Learning each part, will improve one's knowledge of Photoshop. I recommend against taking any short-cuts, as when one walks out the door, into the real world, knowing how to do everything in PS, will be very important.
Adobe has a nice series, Classroom in a Book, for many of their products. For most exercises, there is a "finished" version of that exercise, on the included disc. One could just print out the "finished" version, and then proclaim, "Hey, I finished Adobe Classroom in a Book for PS CS5," but what would they have learned, along the way? Almost zero. Learning is open-ended, and should be a goal, and never-ending.
I've been using PS for about 2 decades, and have made very good living with it. However, one of the main reasons that I come here, is to learn more. One can never know it all.
Also, prior to my retirement, I often did not have the leisure to learn new methods, as I had deadlines, so had to just go with what I knew. When I had downtime, I spent those hours in CiaB, or by taking community college courses in Photoshop (and Illustrator, InDesign, Flash and Dreamweaver), though I already had degrees in Civil Engineering and Cinematography, plus many hours toward my MFA. I did not care about any academic credits - only learning.
Do not take the easy way out. Do each exercise/assignment, as structured. If good, they will teach you more, than just the subject of the exercise/assignment. Should be much more to learn, than just one aspect of PS.
Enjoy your classes, and the exercises. The more that you do learn, the more that you can offer your clients, later on.
Good luck,
Hunt

Workspace - RGB vs CMYK

I work in prepress at a commercial printer, previous to this I worked at a Newspaper. The Newspaper was CMYK and the print company is CMYK plus Pantone Spot colors. Much of what Ive learned has been on the job training (seminars, internet, etc.) since the schooling I had 20 years ago. I work on a PowerPC G5 10.4.11, all CS3 apps + Quark.
My question is about RGB workspace vs CMYK. I've noticed that some people mention working in InD in an RGB workflow and then they let Acrobat handle the CMYK change when creating a PDF. Doesnt this create color issues? RGB is so much more vibrant then CMYK. We have had many problems with clients whose art is RGB, then when its converted to CMYK its nowhere near the correct colors.
Is there something that Im missing? Please understand that I work in a CMYK or Spot color workflow so RGB is a big problem to me.
FWIW, we get all walks of life here, from designers who know what theyre doing (just drop their PDFs into our work flow and go) to the person that has Publisher and Word on their PC so they're a designer....

<[email protected]> wrote in message news:[email protected].. >I work in prepress at a commercial printer, previous to this I worked at a >Newspaper. The Newspaper was CMYK and the print company is CMYK plus >Pantone Spot colors. Much of what I've learned has been on the job training >(seminars, internet, etc.) since the schooling I had 20 years ago. I work >on a PowerPC G5 10.4.11, all CS3 apps + Quark. > > My question is about RGB workspace vs CMYK. I've noticed that some people > mention working in InD in an RGB workflow and then they let Acrobat handle > the CMYK change when creating a PDF. Doesn't this create color issues? RGB > is so much more vibrant then CMYK. We have had many problems with clients > whose art is RGB, then when it's converted to CMYK it's nowhere near the > correct colors. > > Is there something that I'm missing? Please understand that I work in a > CMYK or Spot color workflow so RGB is a big problem to me. > > FWIW, we get all walks of life here, from designers who know what they're > doing (just drop their PDFs into our work flow and go) to the person that > has Publisher and Word on their PC so they're a designer.... Working in RGB, with conversion to CMYK at the last possible stage allows for more device independence. If you are going to work in CMYK you need to know what output device will be used, assign that profile, and then you are pretty much stuck with what you have as far as what the file will output on properly. Larry

Is there a trick to converting JPG from RGB to CMYK without the lossy re-compression?

So I've got around 750 images in multiple categories and folders. Each image has 6 variants - 16 bit TIFF from over-eager beaver photographer, 16 bit TIFF, extracted backgrounds (done by student workers, who do not use English as we are not in the US), then, standardized 3000x2000 (or other suitable aspect ratio) PNG with corrected edges for web and light print, an 1800x1200 JPG for web and a few smaller PNG standards also for web.
The 16 bit TIFFs with Extracted BG are the root files, and a series of actions builds the PNG's. The standardized PNG's are then pumped through actions and Image Processor to create output files.
So I just discovered that a seemingly random number of these are in CMYK. That hasn't been a problem up until now because our website and our printed materials have no problem with CMYK and RGB files.
But now we are starting to hand out these images to our customers - who are only interested in the 1800x1200 JPG and maybe 900x600 PNG files, which are most easily pulled directly from our website rather than sending them the entire 180gb graphics directory.
And some of them are telling us that the pictures are being rejected. Most notably, Ebay does not allow CMYK files.
So damage control- rebuild our entire library of images from the 16 bit TIFFs
OR
rebuild only a couple of different sizes and upload from there, replacing the pictures on the next major update (over the next year).
I am *NOT* concerned about preserving color since 99% of our products are black and shades of grey, with only a hint of color.
I am concerned about the degradation of changing mode on 60-70% compressed images, then resaving again with the lossy JPG compression.
I'm about to start ripping into things with my actions and replacing around 1500 files online, so I'd like to be sure that I'm doing things in the most sensible way.
If there's a tool that can do this conversion without another pass of compression, that would be ideal.

My understanding of the JPG is only middling. I thought I understood that it uses anchor pixels and either a translation table of some sort or difference mapping, using 8 bits per piece of information.
If that were the case, surely changing the translation from CMYK to RGB would be fairly simple.
In this case, the usage is Ebay and they only accept JPG, PNG (and maybe BMP and GIF, I didn't look that closely), but require RGB. I was actually quite surprised to find that JPG allows CMYK since, as you say, anyone dealing with CMYK is going to be dealing with commercial printing and few people who deal with commercial printing would play around with JPG.
I always stick to TIFF or PSD for workflow, but JPG is popular for a reason - when it comes to web, JPG is the only format that can deliver manageable file sizes with full-screen or "large" images for web. Our top level banner photo is 2590x692 and needs to be under 400kb for sane download speeds. PNG couldn't touch that. Even with the aforementioned 1800x1200, PNG is nearly 2mb, while I can maintain very decent quality with a 500kb file with JPG that works well for 'zoom in' type usage.
So there's no way around JPG. It's just annoying that the first person to touch a random selection of the pics was primarily an Illustrator user and saved *some* of the pics in CMYK mode.
It's like that old story about the farmer who didn't want anyone to steal his watermelons, so he cleverly posted a sign "None of these watermelons are poisoned", only to find a note the next day saying "Now, One of these watermelons is...".
Far more work to fix 'some' of the images compared to just doing it right the first time.
But then again, for workers like that, if you can't trust them with an easy job, you could hardly trust them with more complicated jobs...

Conversion formulas from RGB to CMYK

Hi,
I've been writing a Colour swatch tool (in excel! hell yeah!) which allows me to pick a bunch of colours, generate complimentary colours from them, blend between 2 colours in a set number of steps and a whole bunch of other cool stuff, and then output this as a photoshop or illustrator swatch file.
As part of this tool I want to be able to covert the rgb values to cmyk. There is very little information on this on the web and what there is is fairly inaccurate.
For example,
RGB:50,128,128
Converts to CMYK 61,0,0,50 (%) using the formula found at easyrgb.com (this formula is the most prevalent one on the web/web forums)
Photoshop converts these RGB values as CMYK: 80,33,48,8 (%)
While these two colour values are *similar* the ones generated by the easyrgb formulas are nowhere near the photoshop values.
See? stupid useless formulas. (I am aware of the differences and overlap of the two gamuts)
Whilst I know that the conversion done in photoshop is done using ICC templates, and that often these conversions are device dependant, there must be a more realiable way of converting from one colour space to another using good old reliable cold hard maths.
Does anyone know what that might be? you guys at Adobe: I AM LOOKING AT YOU.
Hope you guys can help,
~silvery~
For reference I have included and commented the easyrgb formulas:
First: RGB -> CMY
C = 1 - ( R / 255 )
M = 1 - ( G / 255 )
Y = 1 - ( B / 255 )
Second: CMY -> CMYK
var_K = 1
Initally sets var_K as 1, although this is dependant on variables below
if ( C < var_K ) var_K = C
if ( M < var_K ) var_K = M
if ( Y < var_K ) var_K = Y
This bit finds the smallest value from the CMY range and sets this value as var_K
if ( var_K == 1 ) { //Black
 C = 0
 M = 0
 Y = 0
If var_K (the value that K is calculated from) is 1, then all the CMY values are reset to 0
else {
 C = ( C - var_K ) / ( 1 - var_K )
 M = ( M - var_K ) / ( 1 - var_K )
 Y = ( Y - var_K ) / ( 1 - var_K )
If the value of var_K is anything other than 1 then use the smallest value from the CMY range
K = var_K
The value of K as filtered out from the conditions above

Oliver,
I'm not sure what you mean by the term 'meta' color profiles, but I'll take a stab at what I "think" you are asking. There are some fairly widely accepted "standards" out there for both RGB and CMYK.
In the RGB world, for example, sRGB, Adobe RGB (and to some extent, ProPhoto RGB) have a fairly wide following. These are all ICC profiles, which nail down the boundaries of the color gamut and the definitions of any tri-stimulus combination of red, green and blue. Basically, they are matrix profiles that establish the positions of the Red, Green and Blue primaries, and these positions define the outer limits, or color gamut, of the color space. sRGB is a relatively small color space, so some viewable and printable colors get clipped (sRGB is the general internet, email standard and is widely assumed for many non-color managed appplications, printers, etc). sRGB can handle a fairly wide range of colors, but does clip some colors in brightly colored originals. It has the advantage of being the most widely adopted standard, plus the steps between colors are very close together. I use sRGB for average images, most people pictures, etc. Adobe RGB spreads the primaries further apart, so it describes a wider color gamut. Because the primaries are further apart, the steps are slightly larger from one color to the next, but marginally so. I use Adobe RGB for most of my brightly colored images that will get clipped in sRGB. Adobe RGB is also generally a good choice for images that will ultimately go to a printing press or inkjet. ProPhoto RGB pushes the primaries WAY apart, so it describes a HUGE color gamut...in fact, many of the colors that can be defined in ProPhoto fall outside human vision, and certainly monitors and printers.Due to the wide spacing of steps in ProPhoto RGB, images should be worked in in 16 bit, otherwide you may see some banding and posterization if large edits are made.
In the CMYK world, certain "standards" have been established, mainly for commercial offset printers (both web and sheetfed presses). By creating a standard, they are trying to establish the ink limit, densities, color gamut, dynamic range, gray balance, etc, of a "generic" sheet of commercial printing paper on the average well-maintained press using standard ISO inks, using good process control, mesurements, etc. By it's nature, this process has to encompass a wide cross section of presses, so it may act as a limitation on what some modern presses are capable of, but that's what standards usually do. If a good printer, with a modern press and great process control decides to sidestep the standard, they can probably extend color gamut, dynamic range, etc, but at the cost of no longer being "standardized". If commercial printers are "truly" trying to meet the standard, they will run tests, take measurements, and adjust their entire workflow so it matches the standard, within acceptable tolerances. Lots of shops "claim" to adhere to SWOP or GRACoL standards, but the majority of them don't. Standards for presses make some sense, because blending CMYK inks together (especially if they use ISO standard inks) on paper usually has a reasonably narrow range that works, though the paper makes a huge difference. (the same cannot be said for inkjets, monitors and many other processes, so they generally do not have standards). So for presses, there are standards for matte and coated papers, web presses, sheetfed presses, newsprint, etc. Each of these standards has its own ICC profile (or a family of profiles) that establishes ink limits, color gamuts, etc.
All ICC profiles have the necessary tags and data to comply with the ICC specification. One of those requirements is a "profile connection space", which is usually L*a*b* or a variant. So, an file on your computer may be tagged as an Adobe RGB file, and if you wish to prepare it for a sheetfed press using glossy stock, you could convert the file to GRACoL2006_Coated1v2.ICC (an industry standard profile for No. 1 coated stock on a sheetfed press). Since both files have the ability to "speak Lab" a translation can be made from one color space to the other. The numbers in the Adobe RGB file will be converted to L*a*b* (the universal translator), and then the L*a*b* numbers will be converted to CMYK, specifically GRACoL2006_Coated1v2.ICC. So, now you have a file in CMYK space with new numbers. It is worth noting that RGB has only three colorants to define colors, but CMYK has four. So, while in RGB there is only one way to define a specific color, in CMYK, there are many possible combinations that can generate many colors. This adds complexity to the equation. The CMY colors are called subtractive primaries, and are opposites of RGB (additive primaries). The "K" (black ink) is added for text, line art, neutrality, extra Dmax, and because the CMY inks are not pure and don't deliver a true black all by themselves. If the inks and paper were perfect, you could theoretically get away with CMY all by themselves, except for registration issues, text, line art, etc. Also, the additional "K" ink can help reduce the total ink limit, save ink, reduce costs, and improve quality.
Sorry for the book. This is not a simple subject, and we have only touched the surface.
Lou

I purchased Photoshop Elements Specifically to Covert photos from RGB to CMYK, No CMYK colour?

I selected IMAGE-MODE-appeared RGB, Bitman but no CMYK
I selected EDIT- Colour settings no CMYK
If I can't obtain conversion to SMYK the phoshop is of no use for me.

You need the full Photoshop (current version CS6) for CMYK. You could ask your commercial printer to do the conversion for you if you can obtain a reasonable price.

RGB to CMYK to commercial printer

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