| Sign in: |
| Members log in here with your user name and password to access the your admin page and other special features. |
|
|
|
|
|| SportsShooter.com: Member Message Board
RGB to CMYK help please
Jon Helgason, Photographer, Assistant
 |
Tucson | AZ | US | Posted: 4:01 PM on 02.04.05 |
->> I find myself struggling with RGB to CMYK conversions for longer than I would like. Mainly I am having trouble getting the image to look as good as it did in RGB. I am using a calibrated monitor, going from AdobeRGB to CMYK with the printers ICC profile.
Should I be using a soft proof before the actual conversion? Are their any online guides or books that you recommended? Any tricks or Photoshop actions to set up that would help? |
|
Jody Gomez, Photographer
|
Murrieta | CA | USA | Posted: 4:14 PM on 02.04.05 |
->> I am currently reading "Color Confidence" by Tim Grey. I got mine at Costco in a set of three books about Photoshop and Digital Photography. So far what I've read has been excellent.
You can also order it online at http://www.sybex.com/sybexbooks.nsf/booklist/4316 |
|
Jason Arthurs, Photographer
|
Concord | NH | USA | Posted: 5:25 PM on 02.04.05 |
| ->> Jon, you may already know this, but you can tone in RGB before converting to CMYK and still view the image in CMYK preview, which is a pretty good representation of what the conversion will be like. The keyboard command for this is APPLE + Y. Also, from what I've found there are very few images that look as good in CMYK as they do in RGB. Heartbreaking. |
|
Robert McClory, Photographer
|
Orlando | FL | USA | Posted: 5:48 PM on 02.04.05 |
->> Also, the printer's ICC profile is showing you what their printer is going to do to your image in CMYK. This gives you the opportunity to color correct what you don't like but if you were to use different profiles from different printers and devices, some would be more pleasing than others.
At least you can hammer out a workflow that gets the best results using the tools you have. Better that than the way it used to be where you just sent digital files to the printer and prayed.
RM |
|
Ron Scheffler, Photographer
|
Hamilton (Toronto area) | Ontario | Canada | Posted: 8:37 PM on 02.04.05 |
->> A lot depends also on the color in the photograph that you are converting. If the tones tend to be more on the subdued side, then an accurate transition to CMYK should be possible. The challenge arises when you are dealing with very saturated colors. Reds in particular are difficult to convert faithfully.
What you haven't mentioned is the kind of CMYK printing press the images are going to and the paper being used. If it's newspaper work, then you simply have to live with the fact that ink on newsprint will not allow extremely saturated and vibrant results if compared to printing on glossy coated paper stock.
Use the printer supplied CMYK profile as your CMYK working space in Photoshop. By default, the proof setup should be the CMYK working space. A quick way to toggle between RGB and CMYK preview is Apple+Y (on Macs). It will give you an idea of how the image will translate to CMYK. If you Shift+Apple+Y, the color areas in the image that are out of gamut (not within the reproduction range of the final output method) will be overlaid with a gray tone. It's a quick visual way of seeing how much of the image is out of gamut and potentially problematic. Not all out of gamut colors reproduce poorly, so if you see a lot of gray, you should also try the soft proof to see just how badly the flip to CMYK will be. Probably the quickest way to bring colors back into range is to desaturate them in RGB mode. You can do this a number of ways... Hue/Saturation adjustment either in RGB (master) or in one particular color, or the desaturate brush...
You will also find that as you make adjustments with the Levels or Curves tools, that they tend to build contrast and saturation in images, which may possibly lead to out of gamut problems. It may be adventageous to learn to work in Layers and to selectively mask areas in a given layer to control problem areas. Masking can be as simple as painting areas of the layer black with the paint brush. With layers you also have the flexibility of adjusting the opacity and thus the degree of adjustment.. and of course go back to a given layer at a later time to readjust it. As I mentioned, curves and levels will add contrast and saturation... to avoid some of the color saturation build up, you can Fade the curve or level with Shift+Apple+F and select Luminosity from the pulldown Mode menu. This will apply the density changes to the image without adding the added color satuation.
Once you've converted to CMYK you can bring back colors to a certain extent by using the Selective Colors tool (Image>Adjustments>Selective Color). You can also adjust each of the CMYK layers individually... for example, in the Cyan layer, if you add density, you add cyan... reducing density adds red.
One of the things that may be difficult to get over at first is believing that the muted CMYK version of the image will actually reproduce as a good image on paper.
Are you working with images you created for conversion to CMYK, or are they from other photographers? If the images are yours, you can do yourself a big favor by setting your camera's parameters to create files that are better suited to CMYK conversion. Ideally you will want to set the contrast and saturation parameters lower than the default. By doing this, you will reduce the degree of out of gamut colors created in the original file. It's always possible to add contrast and saturation later in Photoshop - which is better than starting with too much as it is much more difficult to remove than to add without damaging image quality. |
|
Mark Loundy, Photo Editor
|
San Jose | CA | USA | Posted: 1:41 PM on 02.05.05 |
->> It all depends on the device you're outputting to. If you're working with a printing press, you need to work closely with the press operators to determine your CMYK conversion specs.
There is no one-size-fits-all solution.
--Mark |
|
Jon Helgason, Photographer, Assistant
|
Tucson | AZ | US | Posted: 4:03 PM on 02.05.05 |
| ->> Thank you all for your input. I think my issues come up in the very saturated colors as Ron was talking about. It is hard for me to wrap my mind around adding saturation later in Photoshop, but I understand the concept and will play around. With digital images, I tend to think better of starting with more data and taking some away rather than adding some. And yes, it is very hard to see some images that look great in RGB never quite have that pop when converted. |
|
John Fulton, Photographer
|
Pleasant Hill | CA | USA | Posted: 7:23 PM on 02.05.05 |
->> A simple way to understand the differences of CMYK to RGB is to look at the final medium the image will be presented on. RGB will generally be used for internet (subsequently backlit monitors where vibrant light will help support the power of the image) and inkjet printers or high end image processors. I print my images on a Canon I9900. This particular printer is an eight color printer, EPSON I believe is seven colors and so on.
CMYK is used for conventional offset printing and some of the newer digital printing devices such as HP's INDIGO or Xerox's IGEN.
CMYK otherwise known as 4-color process has less of a color spectrum than that of the mediums RGB can be produced on.
Simply put, CMYK has a shorter color spectrum than RGB, and Photoshop wants you get an idea that it will be flatter in some colors. Pastels suck in CMYK as well as vibrant reds, and reflex type blues, (skies and deep ocean blues).
I recently had some images printed at a commercial printer, and they would not take my file in RGB, not because they could not convert, but they insisted I converted the files as to limit the color variance I may have received.
Then there is the whole printer/press check thing once you get to press. That would be a compete new thread.
Good luck and I hope this helps.
John |
|
Return to --> Message Board Main Index
|