TIFF-RGB vs TIFF-CMYK

"viv" wrote in message

Welcome to the world of colour management 🙂

1) Will the TIFF-CMYK version print up it the way it looks in Photoshop or the way it looks in the other applications? Or in each the way it appears in them? (My printer is down for repairs, so I can’t do my own test.).

It depends …

If it’s safe to assume that you’re not using a calibrated monitor then already what you’re seeing isn’t how it really is. The differances may or may not be significant, depending on the intent of the artwork. Apart from that, you *should* be OK if CMYK is REALLY what they want (most printers these days have RGB interfaces – even though the physical ink is CMYK) – but if it’s going to be handled by "the big boys" then you should be OK. Having said that, if what you’re submitting is only a component of the cover then I’d be suspicious – far more likely that your contribution will be part of an effort by others as well – which makes me think the RGB will more likely be required – just a guess though.

2) Is there a way I can save my artwork at the required specs and make it look the same no matter which application I use to view it?

Not that I can think of.

3) What accounts for this difference in the first place?

You’ve created a file that describes the image in terms of cyan-magenta-yellow-black then tried to view it on a device that requires Red-Green-Blue. It’s a bit like writing a page in German then trying to read it in English when you don’t have all the exact-meaning words to translate perfectly between the two languages.

Hope this helps.

"viv" wrote in message
[CMYK image looks different in Photoshop. and Windows Picture viewer]

This leads me to ask the following three questions:

1) Will the TIFF-CMYK version print up it the way it looks in Photoshop or the way it looks in the other applications? Or in each the way it appears in them? (My printer is down for repairs, so I can’t do my own test.).

More than likely Photoshop is providing a more accurate display. It is worth some effort to calibrate your monitor. Use Adobe Gamma if you have a CRT, or a calibration device if you have an LCD monitor.

2) Is there a way I can save my artwork at the required specs and make it look the same no matter which application I use to view it?

This is a complex problem – Photoshop is attempting, by use of color management, to make an accurate conversion for you. Windows Picture is not, or possibly it is converting using using a different color management procedure.

3) What accounts for this difference in the first place?

Photoshop uses an accurate conversion for viewing CMYK images, Windows Picture does not.

If possible, talk with your printer to get an idea of what profile to use. In the absence of other information, and as a rough starting point, for American offset press use SWOP v2 coated or uncoated, depending on the type of stock used.
—
Mike Russell
www.curvemeister.com

This is a complex problem – Photoshop is attempting, by use of color management, to make an accurate conversion for you. Windows Picture is not, or possibly it is converting using using a different color management procedure.

3) What accounts for this difference in the first place?

Photoshop uses an accurate conversion for viewing CMYK images, Windows Picture does not.

If possible, talk with your printer to get an idea of what profile to use. In the absence of other information, and as a rough starting point, for American offset press use SWOP v2 coated or uncoated, depending on the type of stock used.

Still a little confused here, because Windows Picture *will* display the CMYK artwork as I’d like to see it printed if I save it in some format other than TIFF–say JPG. Same for the other applications. Only in TIFF-CMYK is the color scheme radically different, whereas in JPG-CMYK everything is the same across the board, no matter what the application.

What does the TIFF format do to CMYK files to make them look different than CMYK files saved to JPG?

Thanks for the interesting responses so far.

viv

"viv" wrote in message
[CMYK difference in appearance between apps]

Still a little confused here, because Windows Picture *will* display the CMYK artwork as I’d like to see it printed if I save it in some format other than TIFF–say JPG. Same for the other applications. Only in TIFF-CMYK is the color scheme radically different, whereas in JPG-CMYK everything is the same across the board, no matter what the application.

I can’t explain that. Your original post said that RGB looked the same in both apps, and that CMYK was different between PS and WP.

What does the TIFF format do to CMYK files to make them look different than CMYK files saved to JPG?

Again, no explanation. CMYK should look about the same, whether saved in TIFF or jpg.
—

Mike Russell
www.curvemeister.com

Viv,

Your email bounced, so I’m posting here re the screenshots you sent. This is definitely a curious problem.

Perhaps you could send me the files, or cropped sections of them?

Mike

"Mike Russell" wrote in message

Again, no explanation. CMYK should look about the same, whether saved in TIFF or jpg.

Mike,

I never have any occasion to work in CMYK (my printers are all RGB interface (even my Epson 7800)) – so this was new territory for me, but …

I wanted to test out what Viv was saying – interestingly, I chose a scene where I’d photographed my 2 kids in a forrest – so lots of leafy greens in the background. As soon as I converted the image to CMYK I lost about 1/2 the saturation from the greens – kids clothing and skin tones were unaffected – not sure if this is what Viv is seeing?

If you immediately (and repeatedly) do a Ctrl-Z to flick back and forth between the two colourspaces it’s really quite pronounced – I wouldn’t have expected it to be anywhere near going out of CMYK gamut – so I’m interested in anything you come up with.

As a side note, I still have real doubts that Viv needs CMYK – her comment about "not being able to check because her printer is down" raises a red flag – I very much doubt many (any?) home type users would have a CMYK interfaced printer.

Viv (if you’re reading this) – to answer your question about saving the work in a way that will give you the same colour regardless of where it’s opened …. you can’t do this in CMYK format because it’s what’s termed a "device dependant" format – which (in English) tells the printer how much ink to use, but doesn’t define what the characteristics of the ink are (eg an Epson Magenta ink may be a different hue to a Canon Magenta ink – if you use the same amounts, you get a different result). You’ll need to get it looking as good as possible on the screen (and hope that your screen isn’t too far out of colour calibration) then save the file in a device-independant format like LAB colour – assuming that they can open such a file at the other end (won’t be a problem if they have photoshop).

Hope this helps.

"C J Southern" wrote in news:ZmSAf.19486$vH5.905399 @news.xtra.co.nz:

I wanted to test out what Viv was saying – interestingly, I chose a scene where I’d photographed my 2 kids in a forrest – so lots of leafy greens in the background. As soon as I converted the image to CMYK I lost about 1/2 the saturation from the greens – kids clothing and skin tones were unaffected – not sure if this is what Viv is seeing?

If you immediately (and repeatedly) do a Ctrl-Z to flick back and forth between the two colourspaces it’s really quite pronounced – I wouldn’t have expected it to be anywhere near going out of CMYK gamut – so I’m interested in anything you come up with.

Greens and blues show the biggest difference between the two color spaces. CMYK drastically reduces the colors available, particularly in the green-blue range.
There’s a good explanation and graphic example here:
http://jura.wi.mit.edu/bio/graphics/photoshop/colman.htm

"Laura K" wrote in message

Greens and blues show the biggest difference between the two color spaces. CMYK drastically reduces the colors available, particularly in the

green-blue

range.
There’s a good explanation and graphic example here:
http://jura.wi.mit.edu/bio/graphics/photoshop/colman.htm

Thanks Laura – I figured that logically that must be the case – I just didn’t appreciate that CMYK was so – how to put this nicely – "limited".

Cheers,

Colin

On Mon, 23 Jan 2006 10:02:36 +1300, "C J Southern" wrote:

As a side note, I still have real doubts that Viv needs CMYK –

The artwork is for a bookcover and to quote exactly the publisher’s specs:
——————————
TIFF (.tif) file format

CMYK colorspace

300 dpi resolution

Match the dimension of the final trim size, plus an 1/8" bleed on the top, right and bottom sides (i.e. A cover for a 6" x 9" book would need to be submitted at 6.125" x 9.25").

—————————-
This afternoon I copied the files to disk, then took them over to a colleague’s with a suitable printer.

The Photoshop version of the TIFF/CMYK artwork printed up exactly as it looked on screen. (In fact, it turned out much better than I anticipated, with great detail and no banding [my most serious concern], and I could not be happier.)

Printed from within Windows Picture Viewer, however–well, it printed out exactly as it looked, being far darker and more metallic looking. (If Mike Russell received my scans he’ll know what I mean.)

Another oddity: when I go to open the picture from within Photoshop’s Open/Look In [Folder location], the preview thumbnail looks the way it does in Windows Picture viewer, but when it opens up in Photoshop, it looks fine and exactly the way I want it.

Tomorrow I’ll ftp the file into the Publisher’s art department, then try to ascertain how it looks on their end.

The last time I did this everything was in black and white, so I never had any color distortion. Guess I should let that be a lesson.

My thanks to all responders and if anything else suggests itself, please post it.

viv

viv wrote in news:qr38t1htc4h3p2046j307l8ona2loupq3g@
4ax.com:

The Photoshop version of the TIFF/CMYK artwork printed up exactly as it looked on screen. (In fact, it turned out much better than I anticipated, with great detail and no banding [my most serious concern], and I could not be happier.)

Can you fedex that print to the printer? I would and tell them to "match" it — it will become what’s known as a "match print." You’re telling them "this is the way it has to look when it’s printed."
The printer will then make any adjustments they need to make so that what comes off the press "matches" what you sent them. They can do that a lot better than you can because they know their press and the inks they use and what they have to do to the digital version to get it right when it comes off the press.
You can also ask them to send you a proof before they start the press run and fedex that to you for approval.
If they’re close by, you can do a press check — go down when they’re putting it on the press and make sure that what comes off is what you want. The match print is really the best way to go.

In article ,
viv wrote:

I need to submit a piece of artwork for a book cover, with the following specs: TIFF file format, CMYK colorspace, 300 dpi.

There are many things going on here, each of which may be confounding you.

First, as Mike and others have already said, Photoshop does color management and other programs do not. Photoshop will show you a better approximation of how your file will look on press…

….IF you have properly calibrated your system. If you have not, then you’re likely using more or less random color profiles, and what the job will look like on press is a crapshoot.

Second, your printer, which I assume is an inkjet printer, *will not* match a printing press. The CMYK inks used by a consumer inkjet printer do not match in tone the inks used on a printing press; the cyan ink in particular is more blue in a consumer inkjet printer than SWOP cyan printing ink.

Third, you say that the way the image looks is different if you save as a JPEG. If you are using Save for Web to save a JPEG, then Save for Web automatically converts to RGB. If you are not, then likely you are saving your color profile in the TIFF, but you are not saving the color profile in the JPEG.

Generally speaking, your printer should be able to make what is called a "random proof" of your image. Do not trust what you see on your screen or what you print on a consumer-grade inkjet printer. The only way you can truly know what the image will look like on press is to have your printer make you a contract proof, which is a proof made by a special technique that is designed to represent how the image will look opn a printing press. Getting a proof is a normal, ordinary part of the normal workflow for doing graphic arts jobs destined for professional reproduction on a printing press. That proof, not your screen and not a printout on your inkjet printer, is your Bible; that proof is how your image is going to look, and you should make your evaluation and your color adjustments based on that proof.

Talk toy our printer. This dialog is the single most valuable thing you can have when you begin to do work for press. Your printer should be able to tell you more than what you’ve said in this thread; they should be able to give you the separation parameters for converting your image to CMYK, and they may even have profiled their proofing device and their press, and if they have, they can give you profiles to use. (Assuming you have calibrated your system, that is.)

—
Art, photography, shareware, polyamory, literature, kink: all at http://www.xeromag.com/franklin.html
Nanohazard, Geek shirts, and more: http://www.villaintees.com

In article <L_TAf.19508$>,
"C J Southern" wrote:

Thanks Laura – I figured that logically that must be the case – I just didn’t appreciate that CMYK was so – how to put this nicely – "limited".

The CMYK gamut is very limited compared to RGB; many colors in RGB can’t be reproduced in CMYK.

However, the reverse is also true. The CMYK gamut is not contained entirely within the RGB gamut; there are colors in CMYK (including very dark blue-blacks, certain deep fire-engine reds, and pure CMYK yellow, that can’t be reproduced in RGB. This means that your monitor, which is an RGB device, can not show you a perfectly accurate representation of a CMYK image.

This is part of the reason that a contract proof of some sort is essential when you’re worried about color reproduction on press.

—
Art, photography, shareware, polyamory, literature, kink: all at http://www.xeromag.com/franklin.html
Nanohazard, Geek shirts, and more: http://www.villaintees.com

From: "Laura K"

…..

You can also ask them to send you a proof before they start the press run and
fedex that to you for approval.
If they’re close by, you can do a press check — go down when they’re putting
it on the press and make sure that what comes off is what you want. The match print is really the best way to go.

Laura has it exactly right. Particularly for something like a cover, you want a proof before committing to a full print run. This costs a hundred dollars or so, but is worth it, and many printers will insist on it before doing a run.

I’ve been looking at the images, and the CMYK numbers are identical in both images, so the difference in appearance is not due to any problems with the actual color numbers, but with Windows Picture Viewer’s handling of CMYK files. Specifically, the tiff image appears much darker in WPV than in Photoshop.

I used Photoshop to save a second copy of the tiff, this time embedding the SWOP v2 coated profile. WPV’s display of that image was much brigthter, and matched its own jpg interpretation, as well Photoshop’s interpretation of the jpg and tiff images.

My conclusion is that WPV’s default working spaces for CMYK depends on the image format, and tif uses a much darker image.

It’s poor practice to embed a profile in a CMYK image, so I would not recommend that you embed the profile, but do take Laura’s advice about a proof.

There are a couple of other problems with your image that can be easily improved. There is indeed banding in the magenta and cyan channels, and this may show up in the final result. The banding probably occurred because you created your original image in RGB mode and converted to CMYK. A second problem is that you are not making use of pure yellow – since you are representing a figure silhouetted against a sunburst effect, CMYK’s pure yellow will add impact. The third problem is that your image is not trapped – any slight misalignment will create a colored cyan and/or magenta outline around the image.

The first two problems, banding and impure yellow, are probably due to converting from RGB to CMYK, and may be fixed by laying out the image in cmyk as follows. Create a new CMYK image of the same size as your final image, and paste your artwork into a new layer that is set to *darken mode*. In the bottom background layer, recreate your radial gradient going from CMYK(0,0,100,0) to the original red-orange color, approximately CMYK(0,77,100,0). Save the layered verison of your image, and then flatten it and trap it before saving it as a tiff file for printing. The result will be a perfect gradient from pure yellow to red-orange.

If you do not have the original artwork, convert a copy your image to RGB, set your CMYK settings to a Custom CMYK of Max GCR, and copy the K channel to the clipboard – paste this into the new layer as your artwork.

Trap is a little more involved. You could print the figure in pure black, and it would probably look just fine, but as long as you’re paying for CMYK, you may as well go for a rich black such as CMYK(100,53,0,100). So we need to choke the cyan and magenta plates, and trap the yellow plate to prevent fringes due to misalignment.

One way to do this is a variation of the procedure in the PS manual: "To adjust overlapping spot colors".

Use levels to set the black plate to 100 percent, then load the black plate as a selection. Use Select>Modify>Expand to expand by a point or so, and then select the cyan plat, hit delete to choke the artwork – effectively making it slightly smaller. Repeat with the magenta plate. Leave yellow alone, and instead flatten your image and then do an Image>Trap to expand the yellow. Your Greek traveller will now be immune to fringing, and at the same time have a rich black.

If your cover is the only colored art on the page, you could do this as a two color magenta black job on colored yellow stock. Ask your printer if this is available as an option. It may save you money, and will require only that you eliminate the yellow and cyan plates.

And Laura’s advice is probably the most important of all: sign off on a paper proof before printing.
—
Mike Russell
www.curvemeister.com

The image in question is black line art of a walking man set against a sunburst in the form of a yellow to orange radial gradient. —

Mike Russell
www.curvemeister.com