Best technique or program to convert CMYK to RGB or vice versa

[Andy D]

I just had a bunch of file I had to convert from RGB to CMYK & decided to see if how I went about it made a difference, & it did make a large difference.
1- I converted from RGB to CMYK in CorelDraw
2- I converted from RGB to CMYK while exporting from CorelDraw
3- I converted from RGB to CMYK in Photoshop
4- I converted from RGB to CMYK while exporting from Photoshop
I ended up with four different colors & none of them were that great.

I know CMYK has a smaller spectrum than RGB, which is why some colors will never match, but
thought someone here might have a program that does better than most, or a different technique.

 

[dypinc]

For what output device are you converting to and why aren't you letting the RIP convert it to the output device/media profile?

 

[iPrintStuff]

Did you try illustrator? Could probably batch it too.

 

[Andy D]

For what output device are you converting to and why aren't you letting the RIP convert it to the output device/media profile?

Sorry, I should have explained, I was exporting it from RGB to CMYK to sub it out to a vendor that only accepts CMYK files.

Did you try illustrator? Could probably batch it too.

I didn't, I don't have Illustrator... Photoshop has always been my go-to for color consistency in other situations.

 

[Boudica]

I would just do it in photoshop. do you know how to write actions - to automate tasks?
Once you set it up right, you can walk away and let PS do all the work.

 

[dypinc]

Sorry, I should have explained, I was exporting it from RGB to CMYK to sub it out to a vendor that only accepts CMYK files.

I that case have the vendor supply you with a CMYK profile for his output device/media.

 

[Andy D]

Yeah, this is a very bad sign. They should at least accept PMS values, and have a statement about potentially not matching some colors, but to say we only accept CMYK values means they don't know how to run their printers and are not responsible for bad color matches.
What are you getting printed?

Window perf.

 

[DPD]

I just had a bunch of file I had to convert from RGB to CMYK & decided to see if how I went about it made a difference, & it did make a large difference.
1- I converted from RGB to CMYK in CorelDraw
2- I converted from RGB to CMYK while exporting from CorelDraw
3- I converted from RGB to CMYK in Photoshop
4- I converted from RGB to CMYK while exporting from Photoshop
I ended up with four different colors & none of them were that great.

I know CMYK has a smaller spectrum than RGB, which is why some colors will never match, but
thought someone here might have a program that does better than most, or a different technique.

The way I remember this is that each program mentioned has its own conversion engine so I would expect color shifting. Is that what you noticed?

I probably would have let the customer know to convert on their side or expect color shifting.

 

[Pauly]

Why are you converting from RGB to CMYK.
Now the files are smaller than the printers colour gamut?? doesn't make any sense at all.

 

[rjssigns]

Profile mismatch will shift colors. If you're preserving input(embedded) profiles that will also cause issues. Basically you need to know what you're starting with then convert depending on the device(destination profile).

 

[Andy D]

Why are you converting from RGB to CMYK.
Now the files are smaller than the printers colour gamut?? doesn't make any sense at all.

I was exporting it from RGB to CMYK to sub it out to a vendor that only accepts CMYK files.

 

[Adam Vreeke]

What is the color profile that you are originally using in Photoshop? Usually it defaults to RGB 8bit, but this is not the best color profile to be designing in.

In Photoshop go to Edit > Convert to Profile. Normally sRGB is used to design for web. Adobe RGB 1998 is used for print. Normally just normal CMYK profile Working CMYK Web Coated v2 does just fine for converting, but if you are having trouble another solution can be to convert it to U.S. Sheetfed Coated v2 and see if that makes a difference.

If converting color profiles in Photoshop I was taught to never ever ever ever EVER, Go from Image > Mode > selection (unless doing a simple color --> grayscale conversion. But always use the above method.

I was taught this not by my design teachers but by my printing teacher when we jumped on the big 4 color litho presses. Haven't ever really designed in a different color profile before and always convert files using this method, so I can't say much outside of that.

 

[Pauly]

I was exporting it from RGB to CMYK to sub it out to a vendor that only accepts CMYK files.

There's software out there "pdf color servers" that actually do this very good. they convert PDFs from one colour space to another very easily.
I believe it's more for inhouse stuff, but if you do a lot of converting, it may be worth getting.
No idea how expensive it is though, i would believe it's not cheap like any other colour managing software.

Otherwise, i'd use batch in photoshop.

 

[Stacey K]

Not sure if this helps but I use my Pantone Color Bridge and manually match the colors up then send the values to the vendor. It's easy if you're only dealing with a couple colors. Of course the RGB and CMYK never match exactly so sometimes I choose different CMYK than the card suggests, I usually go a little darker if I can't get an exact match. This tool has been invaluable since I bought it from a suggestion on this forum a few months back.

 

[Pewter0000]

Not sure if this helps but I use my Pantone Color Bridge and manually match the colors up then send the values to the vendor. It's easy if you're only dealing with a couple colors. Of course the RGB and CMYK never match exactly so sometimes I choose different CMYK than the card suggests, I usually go a little darker if I can't get an exact match. This tool has been invaluable since I bought it from a suggestion on this forum a few months back.

We use Color Bridge as well, though we rarely have to submit to vendors that don't accept PMS. Our Color Bridge book is very handy for people trying to match banners to business cards to signage, etc.

Agree w/ above, too - a Photoshop action should help if it can change the profile. I have absolutely zero experience w/ Bridge or Lightroom, not sure if that would help with large batches? Really don't know.

 

[Pauly]

We use Color Bridge as well, though we rarely have to submit to vendors that don't accept PMS. Our Color Bridge book is very handy for people trying to match banners to business cards to signage, etc.

Agree w/ above, too - a Photoshop action should help if it can change the profile. I have absolutely zero experience w/ Bridge or Lightroom, not sure if that would help with large batches? Really don't know.

Not lightroom.
That's for editing RAW photographs. Although it would probably work, it's the wrong way to do it.

 

[Andy D]

What is the color profile that you are originally using in Photoshop? Usually it defaults to RGB 8bit, but this is not the best color profile to be designing in.

They are not my files, I think they were provided by the customer.
Another designer in another one of our locations needed help and sent me about twenty files to order out for him, the only thing I did was size everything correctly and converted to CMYK, because the vendor only accepts CMYK files.
It's amazing to me that by changing the method of converting in the same program, it made such a huge color shift.
Below is a printed test I did, the middle color is the original;

 

[Andy D]

Where did you get the original swatch from?
And if this vendor is chosen by the designer at another location, then I'd ask that fellow how he goes about determining PMS to CMYK values for this vendor.

I only had the files, the original swatch was the RGB file, printed from reader to one of our professional paper printers.
On this particular job, I talked to the designer and he told me the blue wasn't critical, it was a random blue he picked.
I really only wanted to know what people's preference was when making similar color changes, mine has always been Photo Shop, & it seems it is for many others as well.

The vendor is a large outfit & on certain product, nobody can touch their prices (not sure about perf).
I like everything about them except for their CMYK art file preference.

 

[bob]

I was exporting it from RGB to CMYK to sub it out to a vendor that only accepts CMYK files.

I've had a few of those. I told them that RGB is what they're getting and to just input that, the RGB, to whatever they were using for a RIP and use it. That I'd pay for the results no matter what. I did so, they did so, and every one, as in all, of them called me with words to the effect "WOW. I didn't know we could do that. Where did all those colors come from?"

 

[De.signs Nanaimo]

I am a small home based shop, but I have over 20 years printing experience. I have worked at a graphic design firm with 40 plus people and was dealing with multiple print jobs in and out of house very day. I outsource all of my current printing, as I just have a 24" plotter and I can tell you it is all about file prep, and accepting and educating your clients to the fact that colour shift in any branding is unavoidable.

A large format printer will print two different colours from the same file depending on humidity and temperature, unless you run in a controlled room, and not many sign shops have that luxury.

I export print ready pdf's from Corel, I convert the bitmaps in Corel to CMYK before PROOFING, and accept that the colour will shift, plus depending on the image I will bump the brightness up 5 to 10% as it will print a bit dark. Stick to default colour profiles, this keeps thing more consistent, and while printing everything in CMYK is not ideal, it will minimize colour problems from job to job, and media to media.

If you have a full time print operator, educating them in colour management is a great idea, they can play with profiles, and gamuts. Most importantly colour profiling all of your equipment together, monitors, printers, profiles everything, but again this is a luxury for larger shops.

I depend on easy repeatable steps that give me the least colour shift but highest quality possible, I have printers that work in CMYK only, some that I use PMS. But mostly I depend on exporting an excellent pdf with no transparencies, gradients or fonts, no extra layers or anything that will screw it up when I can't control what is happening at the actual printer, or RIP.