rgb...cmyk....so cornfused!...ugg

[Big House Signs]

Hey Guys!
Feeling a bit dumb.
So the best designer sign girl I ever had working for me left last week, she had moved to Baltimore a couple months ago, was tired of the 45 minute ride and took a job with a signarama down there. Hope they realize how lucky they are to get this chick.
Now I am designing until my new person starts. I just upgraded to flexi pro 8.6 which I hate...it massacres pdfs and some eps files too. So what I have been doing is opening those files in photoshop at 300 dpi then importing them into flexi to print. My question is in photoshop should I make the files cmyk or rgb?
Thanks for any help! Feeling very frustrated....overworked and understaffed! This is our busiest time....3 weeks ago had hired a new production person who had previous sign experience..but I want things done my way...so I have to watch him like a hawk. Oh for the days when I was just promoting and running the business!
Thanks for listening and please let me know your thoughts on the cmyk/rgb question!
Paula

 

[Letterbox Mike]

I know there's a big debate about this and most people say RGB, but we rasterize all .pdfs in photoshop at 150dpi CMYK and they print great. We're using Onyx, but for us it nails PMS colors every time, we've never had a color issue. I've tried doing this as RGB and while the colors look nice and probably a little more vibrant than CMYK, I've never accurately matched a PMS color this way. CMYK is definitely a smaller color gamut, but I understand how CMYK works and to me it's easier to get more predictable reliable results with it.

 

[Mike Paul]

Keep raster images in rbg.

 

[Big House Signs]

mmm...I do notice if we do it as rgb the colors are more vibrant. Now let me ask you this...if someone sends us a pdf to print...will photo-shop know automatically thatit is a cmyk or rgb file before it opens it?
Sorry for the dumb questions.

 

[bob]

mmm...I do notice if we do it as rgb the colors are more vibrant. Now let me ask you this...if someone sends us a pdf to print...will photo-shop know automatically thatit is a cmyk or rgb file before it opens it?
Sorry for the dumb questions.

Yes.

A PDF is simply a container for various objects in other, often proprietary, formats. Along with each object is sufficient data to describe what it is and recreate the object.

As far as what color model to use, for bitmaps always RGB. In order to display a bitmap if it's in CMYK it must be mapped into RBG in order to display it on your monitor. With this mapping comes a color shift. If you the re-save the image it must then be mapped back into CMYK. Another color shift. All of this mapping and re-mapping is avoided if you just keep the thing in RGB.

Let your RIP do the the conversion into CMYK once at print time, it does this by mapping everything into LAB space and then into CMYK. Most any RIP is far better at doing this than any design package you might be using.

For solid fill vector objects it doesn't matter all that much since the colors are formulaic.

 

[Big House Signs]

thank you Bob.

 

[eye4clr]

PHotoshop will recognize the if incoming files are RGB or CMYK but you have to make a choice what you're going to rasterize to - RGB or CMYK. IOW, photoshop won't automatically make the rasterized version match the original color space of the file.

You do not need to ALWAYS make your bitmaps RGB. The conversion to the monitor's RGB space for display does not effect the file in any way shape or form. It is only an on the fly conversion to the monitor profile.

The simplest method is to convert into whatever space you are the most effective at understanding how to edit and correct the color in. The best performance option is to know the source color space of the incoming file. Then set photoshop to rasterize to that same color space.

BTW, adobe apps are generally better color converters than flexi to wasatch, and often onyx as well. But converting to the output (printer) profile is usually much more practical for most workflows in the RIP.

 

[MachServTech]

BTW, adobe apps are generally better color converters than flexi to wasatch, and often onyx as well. But converting to the output (printer) profile is usually much more practical for most workflows in the RIP.

Caldera RIP may have lic. the Adobe PS engine for the latest version of its rip.

 

[bob]

...
You do not need to ALWAYS make your bitmaps RGB. The conversion to the monitor's RGB space for display does not effect the file in any way shape or form. It is only an on the fly conversion to the monitor profile...

Unless you happen to re-save it. That being the point.

 

[rfulford]

I am sure that many of us have RIPs that force us to rasterize. I have a few Onyx rips and I never trust them with PDF or EPS files. Overall, RGB will be your best bet when you have to rasterize. CMYK will reduce the gamut of any RGB data down the the gamut of your CMYK working space. When you print, your beautiful printer starts looking like a 4color process machine as it happily matches your CMYK input profile.

Adobe RGB on the the other hand can contain most of the standard CMYK working profiles within its gamut. The gamut of the RGB data rasterized in Photoshop is maintained and the CMYK that has been converted to RGB will print surprisingly similar to itself had you not rasterized.

The only exceptions to this that I know or can think of are as follows:

1 - Your rip uses device link profiles instead of icc profiles. Device links convert CMYK directly to CMYK and maintain the black generation in your original CMYK file whereas ICC profiles convert incoming data to a PCC "profile connection space" such as LAB which is then converted to the output profile. Consequently, black is generated according to the method defined when the icc profile was created.

2 - If your original vector file uses spot colors and your rip uses spot color replacements. Despite Adobe RGB's large gamut, there are many Pantone spot colors that do not fit exactly within Adobe RGB. These are mostly yellows and yellow - greens.

 

[javila]

Unless you happen to re-save it. That being the point.

As far as what color model to use, for bitmaps always RGB. In order to display a bitmap if it's in CMYK it must be mapped into RBG in order to display it on your monitor. With this mapping comes a color shift. If you the re-save the image it must then be mapped back into CMYK. Another color shift. All of this mapping and re-mapping is avoided if you just keep the thing in RGB.

You're implying multiple color shifts that do not happen. There will be only one color shift only if you change color spaces, not if you are only displaying/open/saving files.

Simply displaying a CMYK file inside of an RGB device will result in zero actual color shift.

 

[bob]

You're implying multiple color shifts that do not happen. There will be only one color shift only if you change color spaces, not if you are only displaying/open/saving files.

Simply displaying a CMYK file inside of an RGB device will result in zero actual color shift.

That's true. Which word in "if you re-save it" are you having problems with? A color shift will only occur if you re-save the file. Moreover, it can occur each and every time you display and re-save the image, not just once.

If you keep everything in RGB the you'll never have to worry about it. Even about the odd errant keystroke you might make in a welter of confusion, drugged stupor, or whatever.

 

[eye4clr]

That's true. Which word in "if you re-save it" are you having problems with? A color shift will only occur if you re-save the file. Moreover, it can occur each and every time you display and re-save the image, not just once.

If you keep everything in RGB the you'll never have to worry about it. Even about the odd errant keystroke you might make in a welter of confusion, drugged stupor, or whatever.

How does simply saving a file, any file, change it's color? Oh wait, it can if you export to PDF and choose to convert. Otherwise, as mentioned by javila, the only conversion that happens without your intervention is the conversion to the monitor profile for display only. It has zero consequences on the file's actual data.

edit: i just remembered that you may have adobe apps set to convert during opening for profile mismatches. Ha! almost had me there.

 

[bob]

How does simply saving a file, any file, change it's color? Oh wait, it can if you export to PDF and choose to convert. Otherwise, as mentioned by javila, the only conversion that happens without your intervention is the conversion to the monitor profile for display only. It has zero consequences on the file's actual data.

edit: i just remembered that you may have adobe apps set to convert during opening for profile mismatches. Ha! almost had me there.

I'll repeat... Which part of 're-saving' don't you get?

You display a CMYK file, it's mapped into RGB in order to display the thing. Should you subsequently save the image then the RGB image is mapped into CMYK. There is no reason to think that that mapping from RGB into CMYK will produce exactly the same CMYK file with which you started? It may. But then it may not. Probably not.

If you import a CMYK jpg, change nothing, then export the image to another CMYK jpg, re-import the jpg you just make and export it as yet another CMYK jpg. Compare the last two files, the FC command works nicely for this, they are different.

 

[J Hill Designs]

If you open a cmyk file, your monitor will map it to rgb for viewing, but when saving it as as cmyk, it doesn't remap from the rendered view, it just saves it as the original color space...

 

[eye4clr]

I'll repeat... Which part of 're-saving' don't you get?

I get resaving. What does it have to do with some sinister, unwanted color conversion?

You display a CMYK file, it's mapped into RGB in order to display the thing

this is widely agreed upon.

Should you subsequently save the image then the RGB image is mapped into CMYK.

Sorry, lost me here. If you open a CMYK file, maybe make some changes that are not color related, save it...even re-save it, when you open it up again, it will have the same CMYK numbers and embedded profile. Unless you've got some jacked up settings in your color management polices.

There is no reason to think that that mapping from RGB into CMYK will produce exactly the same CMYK file with which you started

True. If you were to CONVERT a CMYK file to RGB, then back to CMYK, you'll definately get some rounding errors in the numbers. As a reality check, the differences would be very small (although undesirable).

If you import a CMYK jpg, change nothing, then export the image to another CMYK jpg, re-import the jpg you just make and export it as yet another CMYK jpg. Compare the last two files, the FC command works nicely for this, they are different

First off, who and why would anyone export, then reimport the same file? I think what's being discussed here, and in the original post, was rasterizing a file with Photoshop. Let's not hijack this nice lady's thread too much.

 

[sjm]

I am sure that many of us have RIPs that force us to rasterize. I have a few Onyx rips and I never trust them with PDF or EPS files. Overall, RGB will be your best bet when you have to rasterize. CMYK will reduce the gamut of any RGB data down the the gamut of your CMYK working space. When you print, your beautiful printer starts looking like a 4color process machine as it happily matches your CMYK input profile.

Adobe RGB on the the other hand can contain most of the standard CMYK working profiles within its gamut. The gamut of the RGB data rasterized in Photoshop is maintained and the CMYK that has been converted to RGB will print surprisingly similar to itself had you not rasterized.

The only exceptions to this that I know or can think of are as follows:

1 - Your rip uses device link profiles instead of icc profiles. Device links convert CMYK directly to CMYK and maintain the black generation in your original CMYK file whereas ICC profiles convert incoming data to a PCC "profile connection space" such as LAB which is then converted to the output profile. Consequently, black is generated according to the method defined when the icc profile was created.

2 - If your original vector file uses spot colors and your rip uses spot color replacements. Despite Adobe RGB's large gamut, there are many Pantone spot colors that do not fit exactly within Adobe RGB. These are mostly yellows and yellow - greens.

Precisely why I insist on all images be supplied in CMYK. Granted RGB has a larger colour gamut but regardless in a CMYK colour space you always lose something.

Of course if the client provides me with a hard copy print from their RGB file then I will gladly accept an RGB image.

You'll find RIP's such as Onyx that do Pantone matching by pass the ICC profile as Pantone supplies the look-up tables in LAB.

 

[bob]

...Sorry, lost me here. If you open a CMYK file, maybe make some changes that are not color related, save it...even re-save it, when you open it up again, it will have the same CMYK numbers and embedded profile. Unless you've got some jacked up settings in your color management polices...

No, you will not get the same numbers. Merely opening the file and then saving it once again is sufficient. You don't have to change a damn thing, the two files are different. You might actually try it before you drop your mouth into gear. I did. It works exactly as I have described.

True. If you were to CONVERT a CMYK file to RGB, then back to CMYK, you'll definately get some rounding errors in the numbers. As a reality check, the differences would be very small (although undesirable).

Assuming a file with a CMYK image, when you display that image, it most certainly is converted to RGB. When you save it, it most certainly is converted back to CMYK. Or do you pose that the software maintains two images, the file image and the screen image? If so, you would be wrong.

First off, who and why would anyone export, then reimport the same file? I think what's being discussed here, and in the original post, was rasterizing a file with Photoshop. Let's not hijack this nice lady's thread too much.

Why? Who cares why, the phenomenon obtains regardless of whether you find the condition sensible or not.

 

[sjm]

Bob, eye4clr is right. Merely opening a file and saving it back out does not change a thing.

Perhaps you can walk us through what you are doing?

 

[GypsyGraphics]

Most working files I keep in RGB, because some PSD features are not available in CMYK color mode. However, I don't handle my own printing so I always make sure I know what my printer or service bureau wants, and that's what they get. Off-set printing though, ALWAYS CMYK!