RGB and CMYK

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RGB and CMYK

Postby flipflop2010 » Fri Feb 11, 2011 2:11 am

Hello Smart People!

I have recently learned the hard way the problems that arise while creating a document in RGB on the computer and having to print it in CMYK. Dark turquois is the main stay of my entire document and it prints out as awful hunter green. My dark gold/almost brown color prints yellow. There are a few pictures of myself included in the document and the coloring of my skin prints horribly.

It actually prints okay on my home computer, however I am printing a booklet that must be professionally printed because my home printer will not print on 11 x 17 in paper.

So- I went to
Tool-->Options---> OpenOffice.org--->Colors
and selected CMYK and created a new font color with the CMYK values. I changed a text box outline to the new CMYK color that appears now in my color pallette selection tool box or whatever its called.

---Does this mean that this color is indeed a CMYK color and remain that? If I went in created several new colors all in cmyk....would that be all I need to do to ensure the colors are printed in cmyk? For some reason, this smells funny and I cant imagine thats its this easy to fix.

I clicked through every single option in the in the Tools/Options menu and found no item where I could convert all of the colors into CMYK.

Furthermore, there was nothing regarding CMYK mentioned in the menus that appear upon clicking the plus sign to the left of "Open Office.org Draw"

Could someone please fill me in on what I am missing? Will simply creating CMYK colors and using them ensure they will be saved as such? Or are these simply rgb colors that match the appearance of cmyk colors in order to print correctly?

I am SO confused and REALLY NEED HELP!! this is a resume portfolio that i need printed asap for an interview on Monday. Ive been trapped at home due to snow and before all attempts to print at kinko's ect resulted in ugly colors. Please help! :crazy: :? :crazy: :crazy: :crazy: :crazy:


UPDATE: I found the following information in the Help Section of the OO.

could someone translate this statement into layman terms for me? :D
OpenOffice.org uses only the RGB color model for printing in color. The CMYK controls are provided only to ease the input of color values using CMYK notation.

Here's a more complete look at what is in this section of help:

Color table
To modify, select the color model: Red-Green-Blue (RGB) or Cyan-Magenta-Yellow-BlacK (CMYK).

OpenOffice.org uses only the RGB color model for printing in color. The CMYK controls are provided only to ease the input of color values using CMYK notation.

If you select RGB, the initials of the three colors will appear and you can set the color from 0 to 255 with the spin button.

R
Red
G
Green
B
Blue
If you select CMYK, the initials of the four colors will appear and you can set the color from 0 to 255 with the spin button.
C
Cyan
M
Magenta
Y
Yellow
K
Black
Preview Field
Displays a preview of the current selection.
Open Office 3.2
I have Windows Vista and Open Office worked on here until 4 days ago. Now its corupted or something. AND it doesnt even list Vista in the drop down list of Operating Systems to choose.
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Re: RGB and CMYK

Postby acknak » Fri Feb 11, 2011 5:13 am

I'm no expert on this--hopefully someone who has some real experience can give you some better advice, but for what it's worth, here's what I know...

If you need accurate color printing, you probably need to use software other than OOo. Industrial printers work in CMYK and standardized color sets (Pantone is a popular one), and OOo supports none of that.

Or, maybe you can find a printer who can/will work with the RGB output from OOo to try and get acceptable printed output. Depending on what you need, you may or may not be able to find a printer like that. If your job can be printed on equipment that works well with RGB, then it might work out ok. If you have a large enough job that it has to be done with multiple color passes (separations), then I don't think OOo is going to work for you.

could someone translate this statement into layman terms for me? :D
OpenOffice.org uses only the RGB color model for printing in color. The CMYK controls are provided only to ease the input of color values using CMYK notation.

I'm not sure there are any layman's terms for this, but maybe this will help: industrial printing hardware prints color in four separate passes over the same piece of paper, each pass adds a single color ink: C, Y, M, K. The separate colors work together, on the paper, to produce the final color. In order to get consistent, accurate colors that look the same on the printed paper as they did on your computer screen, the software must also work using the same color coordinate system. It is possible to convert--approximately--between RGB and CMYK, but the conversion is not perfect, and the printed color will usually look quite different from its appearance on the screen.

OOo can perform this imperfect conversion of CMYK coordinates to RGB, but OOo does everything in RGB and so it's not suitable for printing that works in CMYK.
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Re: RGB and CMYK

Postby aqualung » Fri Feb 11, 2011 11:05 am

I'm a beginner at color management too, and I know much less than acknak.

That said, apparently the best method for ensuring that your desired color will be printed exactly is to use so-called "spot color", i.e., colors that can print solid rather than being made up of a mixture of ink drops from the four "process colors" Cyan, Magenta, Yellow and Black.

In the U.S., the best-known system is the proprietary Pantone Matching System. There are thousands of Pantone color codes. When you specify one of them, you have a guarantee that the print shop will produce exactly that color. (Pantone colors are in fact produced by varying mixes out of a selection of 11 pigments.) And if the print shop does not stock that particular Pantone color or it would be too expensive to do so, then at least you know they can produce a very close match out of the four process colors.

The best way to do this is to get your hands on so-called "color swatches", which are small cards printed solid with these colors. Pick one you like and then specify it to the print shop. Pantone apparently charges money for the swatches.

Lately I have begun learning Scribus, a free open-source desktop publishing software. Unlike OpenOffice, Scribus can produce so-called color separations, i.e., one version of an image or page for each of the 4 process colors. Each of these is used to create a separate printing plate. The paper passes over every printing plate (which wraps around a cylinder inside the machine) in sequence. The combination of their colors gives the finished product.

There is a chapter on color management in their official documentation here -- http://docs.scribus.net/ -- but I have to read it a couple more times to make sure I understand it.

Also, you can download electronic versions of color swatches from Pantone and other vendors. Info on this is found here: http://wiki.scribus.net/canvas/Spot_Col ... in_Scribus

I was unable to register at myPantone as described on that page, but the Swatchbooker software described there worked for me although it crashes often and I had to install Python and Qt for it to work.

Using Swatchbooker I was able to download several Pantone color swatches, which I then converted to OpenOffice color swatch format (.cos file extension). These open fine in OpenOffice and give you the ability to pick colors based on their unique code and on their appearance. However, appearance on screen is only an imprecise guide to what the color will look like when it's printed as your computer monitor is limited to only Red, Green and Blue. Nonetheless, the downloaded color swatches offer the advantage of having a very large palette of uniquely coded colors to choose from. This saves you the trouble of "building" your own colors from OO's color tools and ensures repeatability.

If you have an inkjet color printer attached to your computer, it too may use C M Y K in four separate cartridges but the outcome may not be the same as the CMYK from a print shop.

In any case, you may want to investigate Scribus for its ability to produce color separations and work with a print shop, unlike OpenOffice.
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Re: RGB and CMYK

Postby aqualung » Sun Feb 13, 2011 2:41 am

I found this unusual color-picker application on the Web: Toucan.

It's a powerful Web-only app that is unlike any I've seen before. Lots of programs allow you to assemble a palette of colors from a color wheel, but this one gives you all sorts of "handrails" to guide you along the way. Makes it much easier to come up with sets of co-ordinated colors to form sensible color schemes.

Unfortunately not yet equipped to export to any of the widespread color-swatch file formats. But worth giving a spin, if only for the hands-on experience of it. Includes buttons that toggle the colors to simulate various forms of color blindness / visual impairment, for designers who must adhere to barrier-free design rules.

Free (as in cost-free) but apparently not open-source.

Another nifty Web-only app is Sketchpad, which also includes a color swatch function, but should be seen more as a minimal drawing/painting application than as a groundbreaking color-coordinating tool.
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Re: RGB and CMYK

Postby John_Ha » Mon Mar 04, 2019 10:56 pm

For others searching see What does the CMYK option in AOO do? How is it used?

cmyk 2.gif
Comparison of some RGB and CMYK colours. GIF file used for minimum size distorts colours

cmyk 1.gif
CMYK and RGB gamuts are different - some RGB colours do not have a CMYK equivalent. GIF file used for minimum size distorts colours
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