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CMYK Conversion

Oct 2, 2013, 16:45
Post: #1
CMYK Conversion
I noticed that GIMP only allows a RGB or Grayscale when creating images. Anyone know if they plan on adding a CMYK option by chance? I've seen a few things on You Tube on how to use a plug in to convert, I would like to add on, any suggestions on which sites are more friendly than others.

Thanks in advance for your help!
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Oct 2, 2013, 18:26
Post: #2
RE: CMYK Conversion
Quote:I noticed that GIMP only allows a RGB or Grayscale when creating images. Anyone know if they plan on adding a CMYK option by chance? I've seen a few things on You Tube on how to use a plug in to convert, I would like to add on, any suggestions on which sites are more friendly than others.

CMYK support in GIMP - sometime in the distant future, do not hold your breath.

The plugin for Gimp is Separate+ and is old and not very practical. For CMYK images it is best to start off in CMYK mode (ie. not GIMP) rather than convert from RGB to CMYK with the resulting colour change.
but see...http://registry.gimp.org/node/471

What operating system? I use Separate+ (occasionally) in PCLOS 32 bit. I can get it working in Win7 32 bit and I seems to work in Win7 64 bit - it proofs and exports so must work.

If it is just RGB-to-CMYK conversion then there are other and possibly better ways, such as ImageMagick.

Shutting down for the night now but will look forward to your follow up.

** https://www.gimp-forum.net/ now answering questions**
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Oct 2, 2013, 23:08
Post: #3
RE: CMYK Conversion
I was afraid of that.

I'm starting to get a little more business going with my graphic artwork. While still pretty basic, I've designed some good shirt images, stickers, business cards etc,...so the next logical thing to do is find someone to print for me. The one place I found requires CMYK. I found a few online converters, but I suspect creating the image correctly will get me better results. I have a Windows 7PC 32bit operating system.

Thanks for the tip on Image Magick, I'll check that out.

Josh
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Oct 2, 2013, 23:08
Post: #4
RE: CMYK Conversion
I was afraid of that.

I'm starting to get a little more business going with my graphic artwork. While still pretty basic, I've designed some good shirt images, stickers, business cards etc,...so the next logical thing to do is find someone to print for me. The one place I found requires CMYK. I found a few online converters, but I suspect creating the image correctly will get me better results. I have a Windows 7PC 32bit operating system.

Thanks for the tip on Image Magick, I'll check that out.

Josh
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Oct 3, 2013, 12:30
Post: #5
RE: CMYK Conversion
@crzycowbow, just in case you return

Everything has been a bit of a struggle this morning....

The latest windows separate+ plugin files are 32 bit and they do work on both 32 and 64 bit Win7's.

In win7 32 bit it looks like this.

[Image: KwW3gdX.jpg]

RGB on the left CMYK on the right.

Altenatives,
Do not be put off the online convertors, From what I can see they use the ImageMagick libraries, so you might as well use Imagemagick yourself.
Something along the lines of
Code:
convert image.tiff -profile sRGB.icc -profile cmyk.icc new.tiff
where the *.icc profiles are in the path and correctly named - get rid of any spaces etc.

A GUI, beta and a bit old, is CMYKtool. It is from the same person who wrote the original separate plugin for gimp. I does work in Win7 32bit and Gimp 2.8.6
screenshot http://i.imgur.com/gukgozK.jpg

To save a lot of searching you can get separate+ and CMYKtool here
http://www.mediafire.com/download/azx5y5...tility.zip
About 5 MB - too big for gimp forums, hence the link

The separate+ has the libtiff3.dll that is needed, just pop all the files into your
".\gimp-2.8\plug-ins" folder.
CMYKtool has no installer, copy the folder to program files, make a shortcut to the CMYKtool.bat file. It uses Gimp (or Inkscape) and I have updated the .bat file for Gimp 2.8
A slight advantage over Gimp, it can use 16 bit files.

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Oct 23, 2013, 00:40
Post: #6
RE: CMYK Conversion
(Oct 3, 2013 12:30)rich2005 Wrote:  @crzycowbow, just in case you return

Everything has been a bit of a struggle this morning....

The latest windows separate+ plugin files are 32 bit and they do work on both 32 and 64 bit Win7's.

In win7 32 bit it looks like this.

[Image: KwW3gdX.jpg]

RGB on the left CMYK on the right.

Altenatives,
Do not be put off the online convertors, From what I can see they use the ImageMagick libraries, so you might as well use Imagemagick yourself.
Something along the lines of
Code:
convert image.tiff -profile sRGB.icc -profile cmyk.icc new.tiff
where the *.icc profiles are in the path and correctly named - get rid of any spaces etc.

A GUI, beta and a bit old, is CMYKtool. It is from the same person who wrote the original separate plugin for gimp. I does work in Win7 32bit and Gimp 2.8.6
screenshot http://i.imgur.com/gukgozK.jpg

To save a lot of searching you can get separate+ and CMYKtool here
http://www.mediafire.com/download/azx5y5...tility.zip
About 5 MB - too big for gimp forums, hence the link

The separate+ has the libtiff3.dll that is needed, just pop all the files into your
".\gimp-2.8\plug-ins" folder.
CMYKtool has no installer, copy the folder to program files, make a shortcut to the CMYKtool.bat file. It uses Gimp (or Inkscape) and I have updated the .bat file for Gimp 2.8
A slight advantage over Gimp, it can use 16 bit files.

Thanks for the reply. Honestly I'm a bit frustrated with the seperate+ I cannot seem to get it to print out a "blue" color. Most of mine are a grayish or purpleish tint.

I read a TON of online stuff, and I know that my monitor will look different than print. It's a little nerve racking when I'm about to embark on my free lance business a bit more and not certain the colors I choose will print as the colors I am or my customer will be after.

The link you provided, is there a tutorial on how to install that correctly someplace? I'm not savy enough to try and istall that on my own with out some guidance.

Thanks again for your help.
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Oct 23, 2013, 00:59
Post: #7
RE: CMYK Conversion
On a side note, I think I figured out what you were saying. Not sure if it is working though.
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Oct 23, 2013, 01:01
Post: #8
RE: CMYK Conversion
On a side note, I think I figured out what you were saying. Not sure if it is working though.
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Oct 23, 2013, 01:05
Post: #9
RE: CMYK Conversion
Also when I do seperate it, what destination color space should I choose? Should I be selecting the boxes there? I've pretty much tried all the selections I think and they all give me the same results. Like I said I'm a bit frustrated, so probably overlooking a simple mistake...

Again, thanks for the help.
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Oct 23, 2013, 01:05
Post: #10
RE: CMYK Conversion
Also when I do seperate it, what destination color space should I choose? Should I be selecting the boxes there? I've pretty much tried all the selections I think and they all give me the same results. Like I said I'm a bit frustrated, so probably overlooking a simple mistake...

Again, thanks for the help.
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Oct 23, 2013, 11:38
Post: #11
RE: CMYK Conversion
Quote:..Honestly I'm a bit frustrated with the seperate+ I cannot seem to get it to print out a "blue" color. Most of mine are a grayish or purpleish tint.
If you look at the earlier example showing the comparison you see exactly that.
This is from the online conversion site, as good an explanation as any.
------quote-------
Question: I needed to convert to a CMYK format, I tried your online utility with the "default" (generic) conversion. My ordinary windows "photo and fax" viewer seems to make the resulting image look right again (as far as the HUE goes) on my monitor. But the colors sure seems to have lost their richness and vibrancy.
Is that just because the view is re-converting back to RGB to display it?

Answer: Some RGB colors that you can see on your monitor (in particular, blue, green and all bright vibrant colors) cannot be printed and/or replicated with standard CMYK inks. Keep in mind that, when creating a file for print, you should always make the original file in CMYK color mode before starting to work on it."
-----unquote------

It is all about how commecial printing works. The greyscale images you see with separate+ are masks. Unlike an inkjet printer, the printing machine uses the 'C' mask for cyan then as a separate process the M mask gets overprinted... and so on. Unfortunately CMYk has a smaller 'gamut' - range of colours than RGB

Quote:I'm about to embark on my free lance business a bit more and not certain the colors I choose will print as the colors I am or my customer will be after
It is going to be up to you to advise your customers. A dozen cards printed at home on their inkjet is one thing, commercial printing is another. Tell them to get a proof print before ordering anything.

Quote: The link you provided, is there a tutorial on how to install that correctly someplace? I'm not savy enough to try and istall that on my own with out some guidance.
Not sure what you mean, you seem to have separate+ working. I would leave CMYKtool for later.

Quote:Also when I do seperate it, what destination color space should I choose? Should I be selecting the boxes there? I've pretty much tried all the selections I think and they all give me the same results. Like I said I'm a bit frustrated, so probably overlooking a simple mistake...

Probably no mistakes. Gimp has built-in sRGB colorspace. You need a CMYK profile of some sort. I have all sorts of rubbish installed but an all in one screenshot looks like this.
[Image: U8iEFcO.jpg]

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Oct 23, 2013, 16:56
Post: #12
RE: CMYK Conversion
(Oct 23, 2013 11:38)rich2005 Wrote:  
Quote:..Honestly I'm a bit frustrated with the seperate+ I cannot seem to get it to print out a "blue" color. Most of mine are a grayish or purpleish tint.
If you look at the earlier example showing the comparison you see exactly that.
This is from the online conversion site, as good an explanation as any.
------quote-------
Question: I needed to convert to a CMYK format, I tried your online utility with the "default" (generic) conversion. My ordinary windows "photo and fax" viewer seems to make the resulting image look right again (as far as the HUE goes) on my monitor. But the colors sure seems to have lost their richness and vibrancy.
Is that just because the view is re-converting back to RGB to display it?

Answer: Some RGB colors that you can see on your monitor (in particular, blue, green and all bright vibrant colors) cannot be printed and/or replicated with standard CMYK inks. Keep in mind that, when creating a file for print, you should always make the original file in CMYK color mode before starting to work on it."
-----unquote------

It is all about how commecial printing works. The greyscale images you see with separate+ are masks. Unlike an inkjet printer, the printing machine uses the 'C' mask for cyan then as a separate process the M mask gets overprinted... and so on. Unfortunately CMYk has a smaller 'gamut' - range of colours than RGB

Quote:I'm about to embark on my free lance business a bit more and not certain the colors I choose will print as the colors I am or my customer will be after
It is going to be up to you to advise your customers. A dozen cards printed at home on their inkjet is one thing, commercial printing is another. Tell them to get a proof print before ordering anything.

Quote: The link you provided, is there a tutorial on how to install that correctly someplace? I'm not savy enough to try and istall that on my own with out some guidance.
Not sure what you mean, you seem to have separate+ working. I would leave CMYKtool for later.

Quote:Also when I do seperate it, what destination color space should I choose? Should I be selecting the boxes there? I've pretty much tried all the selections I think and they all give me the same results. Like I said I'm a bit frustrated, so probably overlooking a simple mistake...

Probably no mistakes. Gimp has built-in sRGB colorspace. You need a CMYK profile of some sort. I have all sorts of rubbish installed but an all in one screenshot looks like this.
[Image: U8iEFcO.jpg]

Thanks again for the reply!

Yeah I read a TON of information regarding the difference in RGB vs CMYK. I have a pretty good understanding of that. As for my concerns for customer demand, I already plan on being straight forward with them as well. I just want to make sure I have all my facts straight on these things to prepare myself with questions I know I'll end up getting.

As for the display you shared, I generally do not mess with the source, as I assume it's a default of whatever mode GIMP is in. The destination one is the one I'm most concerned with. Like what's the difference between coated and uncoated? I see you only have 1 check box marked, and that's the one with the source color. Also is the perceptual under the destination the best choice?

The CMYK tool actually worked pretty good, and I'll probably use that for the time being. At some point in time when I start schooling for graphic arts, I'll end up with Adobe CS6, and have to learn all over again...LOL Doing these side jobs are what will help me fund my schooling.

Again, thanks for taking the time to answer these questions...it's very helpful to me.
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Apr 10, 2014, 10:48
Post: #13
RE: CMYK Conversion
Yes, this is a problem. Is the CMYK for GIMP up now?

If not, how do you convert GIMP's rgb to CMYK? Is there a free to use app that can do that?
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Apr 10, 2014, 11:27
Post: #14
RE: CMYK Conversion
It looks like you have not read any of the posts here on CMYK so the best bet for you will be

http://www.rgb2cmyk.org/

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