RGB to CMYK

[james.hobbs00]

I have a RGB Photoshop file and I want to change it into CMYK. Unfortunately the colours are changing slightly, Is there any way to prevent this.

 

[Joe]

Try using a different profile when converting.

 

[Gianni_S]

You may also test other rendering intent. However the differences in gamut between RGB and CMYK color methods are quite evident.

 

[dabob]

If its the blues and reds that are shifting . . . well thats just the colorspace from what I understand Cyan is the "truest blue" in the CMYK pallet so for a darker blue magenta is added and presto purple . . . and Magenta is the reddest so for a fire engine red add yello . . . and presto you get orange . . . just a product of the technologies limits . .

 

[arossetti]

I have a RGB Photoshop file and I want to change it into CMYK. Unfortunately the colours are changing slightly, Is there any way to prevent this.

I'm going from a Ferrari to a Smart Car and now my acceleration sucks

You can try a devicelink profile to do the conversion, that might help slightly. Which CMYK profile are you going to?

 

[Dov Isaacs]

I'm going from a Ferrari to a Smart Car and now my acceleration sucks

You can try a devicelink profile to do the conversion, that might help slightly. Which CMYK profile are you going to?

Devicelink technology is primarily used for CMYK to C'M'Y'K' types of conversions due to the problems of 4 colorant to 4 colorant conversions via a 3 colorant intermediary. It really isn't going to help much if at all for a direct 3 colorant to 4 colorant transform. The underlying issue here is gamut!

- Dov

 

[james.hobbs00]

I use a Coated FOGRA39 (ISO 12647-2:2:2004). I also tried FOGRA27 (ISO 12647-2:2:2004), but it only gets worse. I'll try to call the printservice I am going to use. Maybe they can do the conversion. On their website I have downloaded ISO Coated v2 300% and installed it but now I don't know which one to pick in the dropdown menu, I can't seem to find it.

 

[Stephen Marsh]

There are some “tricks” that are often very much image dependent, however it sounds as if things are as good as they get without seeing the original image.

Fogra39 and ISO Coated v2 300% are both targeting the same output condition, however the later uses a 300% total ink limit, rather than a higher limit which is more common for the standard ISO Coated v2/Fogra39 profiles. Yes, Fogra27 would probably offer a “worse” result than Fogra39 when compared to the original image.

Keep in mind that other people will not see the RGB version, so as long as the CMYK version is good, then it will be “just as good as other CMYK images”.


Stephen Marsh

 

[prepressdork]

The only two profiles I have ever used for converting RGB to CMYK are the Photoshop5DefaultCMYK and GRACoL2006_Coated1v2 (I use the Photoshop one much more though). Either of those profiles should give reasonably acceptable results. Ultimately, some color ranges convert better than others (less visual difference).

pd

 

[Tim-Ellis]

Ok...I'm no expert but I think you need to view your converted CMYK image in soft proofing mode to see how it might appear when printed. Otherwise you are looking at a RGB device doing an impersonation of a CMYK device whist allowing for a theoretical substrate.

http://www.colourphil.co.uk/photoshop-proof-colour.shtml


Also, you should check the gamut warning to see if colours have been clipped as you move out of the larger colour space of RGB. If your picture is a bowl of strawberries, your going to have to compromise something.


http://www1.udel.edu/cookbook/scan-print/gamut-hue-sat/gamut-huesat.html

Good luck

 

[Red_Right_Arm]

I have a RGB Photoshop file and I want to change it into CMYK. Unfortunately the colours are changing slightly, Is there any way to prevent this.

I think a lot of people here might be focusing in too much on literally answering your question without getting some context behind it.

Why are you converting this in the first place? No one would convert an RGB image to CMYK for shits and giggles. You have to be doing this for a reason that you're really after. What is that reason? That may determine the best method for how to do what you are after.

 

[james.hobbs00]

I`ve created some artwork in Photoshop. The PS file was in RGB Mode. I needed to convert it to cmyk for printing. I just couldn't get it right so I called the place where wanted to print it. I`ve sent them the file and I don`t know how, but they got it done. Hopefully the printed stuff will look the same! So thanks to everyone, I let you know how if it worked out.

 

[Kreso_Zagreb]

James,

What is your intent with that file? Do you know what will be end result? Do you know the kind of paper? Have you tried to ask printing house which composite profile you should use? Whenever you're converting from large to small space color shift will occure. You might want to give us here more info in order of getting the best advice.

 

[michaelejahn]

I have a RGB Photoshop file and I want to change it into CMYK. Unfortunately the colours are changing slightly, Is there any way to prevent this.

Simply, the answer is "no" with a 'possibly' caveat - as RGB colorspace uses light to render a color that is projected onto a monitor, it is possible for RGB colors to be "viewed" and "perceived by you eyes" as brighter, more saturated than can be attainable by most CMYK printing systems. Bright saturated Oranges ( like one might see on a printed bag of Cheetos ) are achieved not using CMYK inks, but by printing a spot color ink that is "like" Pantone 151 - you can display that color fairly well on a monitor, but if using CMYK inks, it is impossible to reach that colors gamut.

Now, for the caveat - professional photographers and graphic artist who work in the print industry often overcome this 'difference" by calibrating their monitors so they "will display like they will print"

In that way, they will not create colors that can't be printed reliably. You can ( of course ) work your final images in CMYK as well - with a calibrated color managed monitor, to avoid these "surprises"

I have worked with folks who do their best to swatch match - that is, they have to photograph an item, then somehow do their best to simulate that items color in print. This is not a simple process. Perhaps this stinky old draft of a talk i prepared might help you get your head around some of the tools and challenges...

https://docs.google.com/document/d/1...zMeCkQ/preview

 

[halmac]

In the old photoshop I would go to image/mode and change from rgb to cmyk. In the newer photoshop you are warned about doing this. Now I go to edit/assign profile and it works much better. Very little color shift.

 

[Stephen Marsh]

In the old photoshop I would go to image/mode and change from rgb to cmyk.

That was the only option in the very old versions…

In the newer photoshop you are warned about doing this.

This is a bogus “warning”, pure F.U.D. – it is just that convert to profile is more flexible, not that mode/cmyk is “bad”.

Now I go to edit/assign profile and it works much better. Very little color shift.

Are you sure that you don’t mean edit/convert to profile? One can’t assign a CMYK profile to an RGB file.


Stephen Marsh

 

[michaelejahn]

In the old photoshop I would go to image/mode and change from rgb to cmyk. In the newer photoshop you are warned about doing this. Now I go to edit/assign profile and it works much better. Very little color shift.

Well, what can I say, the old Photoshop simply did not predict very well what was REALLY going to happen, now did it. The "new" Photoshop can.

 

[andy_baz]

Whether using old or new Photoshop converting mode from RGB to CMYK is in fact doing the same...converting to a profile, the working profile defined in your colour settings).

Just to be clear RGB is a screen colour model (using light) CMYK is a printing colour model (using ink). A conversion has to take place from RGB to CMYK at some point of the process whether it is done manually or by the printer/RIP.

The modern way of working is to leave images RGB until the point of being RIP'ed and have the RIP/workflow use a pre-defined profile suitable for the intended output. (i persoanlly use FOGRA 39 for coated and FOGRA 29 for uncoated these are general ISO standards and fit for most purposes).

To predict how an RGB file is going to print you need to either Soft Proof in your desired software (ie photoshop/InDesign/Acrobat) and preview using the correct output profile or generate a colour managed Hard Proof (ie using a colour calibrated large format printer).

Hope this helps

Andy Barrington

http://www.barringtonprint.com

 

[james.hobbs00]

So, here is the whole story: I´ve created a Flyer for a customer. My client handed artwork to me, which originally was created in PS, for screen. He wants the exact same artwork placed as background for his flyers. So I had trouble to convert the artwork from RGB to CMYK without changing the look of the colors. I´d downloaded the color profile from the Link below. I tried around, changed the profiles in PS but it just didn´t work. When I installed the profile I could´nt even find it in PS, I think the name of the profile like it´s displayed in PS after installing, just changed. Then I´ve called the printservice I was going to use and sent them the RGB PS file. Luckily, they managed the conversion and I was able to finish the flyer and get print data done. Now I have received the flyers and my client and I are very happy. This was my first time using a online printservice, my customer insisted on working with them. Overall I am happy now and I definately would order again. For some of my clients this will be a really good alternative.

https://www.printcarrier.com/en/temp...downloads.html

 

[andy_baz]

The intended out profile needed to convert the job from RGB to CMYK is decided solely by the people who are printing the job for you and what presses/setup they use.

If you know who is printing the job then it is best to contact them and ask what profiles they use, and ask whether they are ok with you doing the conversion or (most likely) they would do the conversion the in their print workflow. If you dont know who the printer is then using standard profiles like FOGRA is the best way to go.

You might be wondering: "If they are doing the conversion how will i know what the final output will look like?" this is where soft proofing (or properly calibrated hard proofing) comes into play. The printer you are using should always be able and willing to provide you with the press profiles they use, obtain these and use them in your chosen application to proof preview the files. Providing your setup is colour calibrated correctly you should be able to preview the finished job to a satisfactory standard.

Having said all of this ultimately the finished job quality and colour accuracy is dependent on how good the printer and the pressmen are who are physically printing the job. All the colour management in the world cant account for a bad printing/printers!