rgb to cmyk question

In short, no…
There are colors in the RGB spectrum that are simply outside what you can make with CMYK – likewise – there are colors in CMYK that are outside what you can make in RGB.

Depending on the complexity of the art – you ‘could’ include a tempo or hexachrome ink if you absolutely have to have a specific color or two – but your printing cost can go thru the roof pretty quickly if you don’t plan ahead.

n8

I was just told by a printing company that the image I have to send them should be in cmyk mode. so I made the conversion but now my image has lost

a

lot of it’s livelyness. is there any way I can obtain the colours in cmyk mode? if not, is there anything I can do to approach the colours of the

rgb

original?

thanks.

"tube jerk" wrote in
news:meo0c.1535$:

I was just told by a printing company that the image I have to send them should be in cmyk mode.

That’s correct, at least for process color. Any offset printshop would tell you that.

so I made the conversion but now my image
has lost a lot of it’s livelyness.

Yep. The CMYK gamut is smaller than any of the RGB ones.

is there any way I can obtain the
colours in cmyk mode? if not, is there anything I can do to approach the colours of the rgb original?

Basically, learn to work in CMYK for something that is going to print.

If that sounds unhelpful, bear in mind that this is what *everyone* has to do.

There are colors in the RGB spectrum that are simply outside what you can make with CMYK – likewise – there are colors in CMYK that are outside what you can make in RGB.

*** I’m not sure about that last one. 🙂 If you meant that process inks can’t always reproduce similar hues to spot inks, that would be true. If you have info on how the RGB colorspace has less tonal range than CMYK, please post the link.

Depending on the complexity of the art – you ‘could’ include a tempo or hexachrome ink if you absolutely have to have a specific color or two –

but

your printing cost can go thru the roof pretty quickly if you don’t plan ahead.

*** The other thing to check is how it’s being printed. If it’s being done on a short-run digital machine, it might be best to keep raster images in the RGB colorspace let the driver for that machine determine how it should be separated. This way you know the maximum "vividness" of the hues is maintained.

Before running an entire job, consider sending two 8.5"x11" documents to the machine, one with RGB files, the other with CMYK files. Pick the result that looks better to you. It’s a different game when sending to an image setter… so more research is required on how it’s being printed.

JD

you can try messing around with some of the colors in cmyk mode. that’s what i do. i’m not sure if there’s anything else you can do for a perfect match of the rgb colors.

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"tube jerk" wrote in message

I was just told by a printing company that the image I have to send them should be in cmyk mode. so I made the conversion but now my image has lost

a

lot of it’s livelyness. is there any way I can obtain the colours in cmyk mode? if not, is there anything I can do to approach the colours of the

rgb

original?

thanks.

"Jeff H." wrote in message

There are colors in the RGB spectrum that are simply outside what you

can

make with CMYK – likewise – there are colors in CMYK that are outside

what

you can make in RGB.

*** I’m not sure about that last one. 🙂 If you meant that process inks can’t always reproduce similar hues to spot inks, that would be true. If

you

have info on how the RGB colorspace has less tonal range than CMYK, please post the link.

It depends on the *specific* RGB colorspace involved. For example, this is certainly true for sRGB. If you use sRGB as your working space, and then convert to CMYK, you will never get more than 75%-85% cyan in your CMYK separations. Common knowledge, lots of links out there.

This is one of the reasons why, along with other potential device-dependant clipping issues, sRGB is not recommended for any printing – except in those cases where the machines have been dumbed down to only accept files tagged with sRGB (e.g., Fuji Frontier & Noritsu wet-process printers).

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Simply observe the RGB and CMYK color models. You’ll see that intense reds, greens, and blues are outside of the CMYK gamut, and as such, can’t be reproduced on print.

Likewise, there are areas on the CMYK (CIE Space) curves that are outside of the RGB gamut – intense Cyan, Magenta, and Yellow. The phosphors in computer monitors can’t display the spectral locus (pure) colors any more than you can create pure RGB colors on paper.

Check out
http://www.nebulus.org/tutorials/2d/photoshop/color/gamutsmb .gif for a visual overlay of these 2 color spaces…

n8

*** I’m not sure about that last one. 🙂 If you meant that process inks can’t always reproduce similar hues to spot inks, that would be true. If

you

have info on how the RGB colorspace has less tonal range than CMYK, please post the link.

Depending on the complexity of the art – you ‘could’ include a tempo or hexachrome ink if you absolutely have to have a specific color or two –

but

your printing cost can go thru the roof pretty quickly if you don’t plan ahead.

*** The other thing to check is how it’s being printed. If it’s being done on a short-run digital machine, it might be best to keep raster images in the RGB colorspace let the driver for that machine determine how it should be separated. This way you know the maximum "vividness" of the hues is maintained.

Before running an entire job, consider sending two 8.5"x11" documents to the machine, one with RGB files, the other with CMYK files. Pick the

result

that looks better to you. It’s a different game when sending to an image setter… so more research is required on how it’s being printed.
JD