Printing grayscale images in CMYK?

[Asterix]

Hello.

Is there any advantage in converting grayscales to CMYK?

One senior designer at a place I'm currently working rants hysterically that by converting to CMYK you get a deeper 'richness' in the final image, but I'm thinking all you get is muddy looking blacks.

We're printing on uncoated stock with a 20% dot gain. Things aren't helped much by the quality of the 'grayscales' which invariably come over as RGB files at a less than desireable dpi for their intended output.

I'm just wondering whether there's any advantage to going this route at all...

Many thanks in advance.

[Michael Josefowicz]

My experience is that it can make a significant difference. The problem is that it's tricky to get the curves right. And when you are on uncoated stock is even worse. Then you have to know that the grey balance is pretty under control in the printing process.

If you have the time to do some iterations on getting it right, AND are pretty confident that the actually printing process is stable, my experience is that it can make a huge difference. If not, you'll be going down a worm hole. Been there, done that. It's not pretty.

[Tech]

This is a popular view among designers, especially those "seniors". This is completely based on individual opinions and NOT a fact. Grayscale images printed 4C tend to have a warm color look, some interprets this as "richer".

I'm an advocate if you want richer grayscale, instead of printing as 4C images, convert your images to duotone to bring out better tonality in your grayscale images. Be sure to adjust color curve to find the correct balance and save file in EPS.

Of course, if your entire project is 4C and some "senior" insist on printing as 4C, I would probably let them have what they want and not waste time educating them or do the work for them.

[Michael Josefowicz]

Guilty as charged. I am a senior.

I aqree that duotones or even quad tones with four different blacks is the optimal way to go. Problem is that it's become pretty hard to find two color or 4 color black printing processes. A couple of years ago I did a tri tone with stochastic screening that was awesome.

It also depends on what the output engine is. I've had amazing results on the Igen because the black toner has an amazing density. Single color black is definitely the way to go. Don't have any experience with other digital devices.

Using 4c offset that is not under grey balance control, or if you don't have the time to get the curves right, I also agree that it's not worth the trouble.

I wouldn't just give them what they want. Cause when it comes out yucky, they are going to blame you anyway. Might as well try to explain the downside up front.

All depends on the customer, the job and what is going to work for them.

Just the two cents of this " senior"

[Lukas Engqvist]

It is a shame that there isn't the alternative to choose what GCR to use on a per image basis. Greyscales can look really good with an above average GCR. filling in the spaces on the middtones gives a softer, smoother image especially in portraits. The trick is to keep the bulk of the grey scale in K so that variations are minimal. We just did a 5 colour print run with CMYK+K, it was mainly to have a nice rich black backround without getting too much ink. first K at 80% second at 100% I love trapping for neg text

[Michael Josefowicz]

i'm not a hands on technician so this may be dumb. But isn't there a switch in PS that allows you to adjust the amount of GCR?

[Lukas Engqvist]

No GCR adjustments available for the designer/prepress operator in the design software. Features that involve hacking the output files don't count

[Michael Josefowicz]

What about if you work RGB than convert to CMYK at the last step?

[Asterix]

Thanks for your helpful replies.

I've been looking at Blatner & Fraser's take on this and although they don't address it directly they do offer some advice which would be:
a/ Make all initial tonal adjustments in RGB before going to greyscale, then
b/copy the black plate and paste it into a new CMYK file duplicating it for each channel, then
c/ Apply curves to the CMY channels

This kinda makes sense as converting directly via the Mode option loses information by stretching the pixal content so, I believe, you lose detail in the midtones.

Duo's, Tri's, or Quadtones would certainly be an option too.

I'm more concerned that in 'their' hands they're more likely just to click on the 'Mode' button and lose alot of info in the first step...

[Michael Josefowicz]

When I was teaching production to designers, we were pushing them to work in RGB mode for images. Stay away from the mode button. Give your printer RGB. The big problem was that almost every printer the students talked said they required CMYK files...