CMYK Output of Digital

John Adler101560 · Nov 15, 2002

Hi all,

To those of you who have had your digital files reproduced on a CMYK printing press, what do you think of some publications insistance on a minimum 300dpi original (at the printed size) with no interpolation allowed?

One poster here said that CMYK printed output is a different beast all-together than the results we might achieve at home on a good printer, and that 300dpi is necessary to achieve good-looking results.

Thanks much,

john

Veniamin Kostitsin II · Nov 15, 2002

Well ... in my experience, 300 dpi file from the original with postprocessing and interpolation which is acceptable to you will give you good results. if you can make a decent inkjet-print (better yet on a cmyk thermosublimation proofer if you have access to one. i usually do it on an imation rainbow machine and am very happy) of this file, the offset printer should be too.

do i make any sense ? if not the short version : if you can make a good 300 dpi (image resolution, not printer resolution) print of it on an inkjet at the size it should be reproduced in press, you have a go

this one was published on a doublepage layout and held its ground.

i understand it is b/w ... but i've done colour too

cheers

veniamin kostitsin
http://www.digitalimage.at/

John Adler922 said:
Hi all,

To those of you who have had your digital files reproduced on a
CMYK printing press, what do you think of some publications
insistance on a minimum 300dpi original (at the printed size) with
no interpolation allowed?

One poster here said that CMYK printed output is a different beast
all-together than the results we might achieve at home on a good
printer, and that 300dpi is necessary to achieve good-looking
results.

Thanks much,

john

--
Veniamin Kostitsin II
http://www.digitalimage.at/

Ethan Hansen · Nov 15, 2002

John Adler922 said:
Hi all,

To those of you who have had your digital files reproduced on a
CMYK printing press, what do you think of some publications
insistance on a minimum 300dpi original (at the printed size) with
no interpolation allowed?

You are likely running into a combination of anti-digital snobbery and bad experiences with previous digital submissions. On the snobbery front, many publications have AD's or photo buyers who still do not believe digital cameras are up to the task. If the image does not come from a 4000-6000 dpi drum scan, they want no part of it. Res up your images and submit them anyway. Don't ask, don't tell.

On the other hand, the proliferation of digital cameras has many magazines bitching about the lousy quality of recent submissions. From their perspective, everyone with a digital camera is running around taking pictures ... ahem, images ... and finding something promising in the noise. Usually, the subject was not framed correctly, so out comes the Photoshop crop tool. The only problem is the resulting image is tiny, so bring on PS interpolation, QImage, GF, SI, etc. The final product might have had hope if the photographer used a longer lens, moved closer, or just framed properly in the beginning. The "300 dpi, no interpolation" rule is aimed at filtering out the majority of such shots.

John Adler101560 said:
One poster here said that CMYK printed output is a different beast
all-together than the results we might achieve at home on a good
printer, and that 300dpi is necessary to achieve good-looking
results.

The dpi needed depends on the printer and paper used. A press running uncoated newsprint needs much lower resolution than a 2400 dpi imagesetter printing on high quality glossy stock. Talk with your printer to see what they need. For stock sales or selling to a photo buyer without a specific intended usage, 300 dpi is as close to a standard as anything.

--
Ethan Hansen
http://www.drycreekphoto.com/

Russell Stewart · Nov 15, 2002

As mentioned in the previous post there is a lot of digital snobbery and "un-truths" in the printing world still.

300ppi is the normal or most common ppi used for CMYK images when printed in magazine or brochure. Having said that, it is also common practice in the industry to run the images up to 150% (sometimes 180%) of their size and they are still VERY acceptable.

Upsampling?? Not an issue if you do it correctly... ie upsample within the image's capabilities and don't create jaggies/artifacts when doing so.

Also, you need to consider ICC profiles for your CMYK conversion. Talk to your printer or pre-press house and get a copy of the profile they are using, since just converting to CMYK will normally make for a "muddy" result.

SWOP Coated is a good place to start, I have found that my pre-press house requires only a little ICC tweeking from Swop Coated to get my images as they want them. So I prepair my images in RGB as normal, colour matching to my monitor (WYSIWYG) and then covert to CMYK applying my working ICC profile.

So far ALL my CMYK print reproductions have been very good.

Hope this helps

Russell

John Adler922 said:
Hi all,

To those of you who have had your digital files reproduced on a
CMYK printing press, what do you think of some publications
insistance on a minimum 300dpi original (at the printed size) with
no interpolation allowed?

One poster here said that CMYK printed output is a different beast
all-together than the results we might achieve at home on a good
printer, and that 300dpi is necessary to achieve good-looking
results.

Thanks much,

john

John Adler71924 · Nov 15, 2002

Thanks for your replies. The consensus seems to be, if you can get good-looking output on an ink-jet, offset printing shouldn't require any more resolution.

I asked because I'm weighing the advantages of the Kodak 14N vs. the Fuji S2. From what I can tell, the 14n only gets you a little bigger at the same resolution, and I've seen some gorgeous 48" prints from the S2.

Thanks again,

john

Andrew Rodney · Nov 16, 2002

John Adler922 said:
To those of you who have had your digital files reproduced on a
CMYK printing press, what do you think of some publications
insistance on a minimum 300dpi original (at the printed size) with
no interpolation allowed?

Find out what linescreen the job will be printed. Double that and you have a rough idea of the rez you need. So, if your print run is 150lpi, you would need 300 ppi of data. Once you get above 150lpi, you can lower the quality factor to 1.5 the linescreen.
--
Andrew Rodney
http://www.digitaldog.net

Richard Goulden · Nov 16, 2002

Hi John,

John Adler71924 said:
The consensus seems to be, if you can get
good-looking output on an ink-jet, offset printing shouldn't
require any more resolution.

This is not true at all. Almost all modern inkjets used very different screening
than offset litho printing and need no better than 180ppi. It is conventional

screening for offset litho printing that requires (rule of thumb) 2 pixels per screen
line which at 150-175lpi is 300ppi. If it's newpaper work you need no better
than 170ppi for a screen ruling of 85lpi.

I have just completed a 12 page Christmas brochure with a 100,000 print run
on a web offset press. All images taken on the D60.

Before I hand the images over to the agency I always set them to 300ppi. That way
there are never any arguments. The results are excellent and stack up along side

conventional film scans very well. A few stock product shots were used in the catalogue
too.

Make sure you have a correctly calibrated monitor. I also have a very, very good rgb

to cmyk look up table loaded into Photoshop to get excellent conversions and would not
want an ad agency or repro house to ruin all my hard work....

Regards,

Richard

John Adler said:
Thanks for your replies. The consensus seems to be, if you can get
good-looking output on an ink-jet, offset printing shouldn't
require any more resolution.

I asked because I'm weighing the advantages of the Kodak 14N vs.
the Fuji S2. From what I can tell, the 14n only gets you a little
bigger at the same resolution, and I've seen some gorgeous 48"
prints from the S2.

Thanks again,

john

Veniamin Kostitsin II · Nov 16, 2002

with no gibberish attached

Andrew Rodney said:
John Adler922 said:

To those of you who have had your digital files reproduced on a
CMYK printing press, what do you think of some publications
insistance on a minimum 300dpi original (at the printed size) with
no interpolation allowed?

Click to expand...

Find out what linescreen the job will be printed. Double that and
you have a rough idea of the rez you need. So, if your print run is
150lpi, you would need 300 ppi of data. Once you get above 150lpi,
you can lower the quality factor to 1.5 the linescreen.
--
Andrew Rodney
http://www.digitaldog.net

--
Veniamin Kostitsin II
http://www.digitalimage.at/

John Adler71924 · Nov 16, 2002

Again, thanks for all the good information.

-john

David Barkin · Nov 16, 2002

Hi John

First: The people you're doing business with don't know a damn thing. You should be able to send them a sample print the way you want the image to look and along with that send them the RGB image and let them do the separation.

Anytime there's a conversion from RGB to CYMK the image becomes much less adaptable in the future.

When you print on your home computer YOU are doing this conversion. The printer driver does it for you accoding to the option you set in the driver.

You should NOT send them a CYMK image.

Second:As far as the size of the image goes there's a rule of thumb. The pixels multiplied by 2.6 divided by the output machine. For example if you're image is 1600 pixels and you were printing at 2400 dpi then

1600 x 2.6/2400 = 1.7

As you can see such an image would equal only a very small print. Size your job according to this nrule of thumb.

Finally, there's the screening method being talked about. Few home computers allow using raster screening. Certainly all the home Epson's including the 3000 do not. They print via something called ordered dither. The image is merely converted into dots with no screening at all.

Raster Screening is necessary for press runs as ordered dither cannot at this time be reliably printed. If you want to see the difference merely hold up a home made print to a magnifying glass and compare that to the "pattern" made in a magazine photograph. In a magazine you are seeing the "raster pattern."

Dave

Andrew Rodney said:
John Adler922 said:

To those of you who have had your digital files reproduced on a
CMYK printing press, what do you think of some publications
insistance on a minimum 300dpi original (at the printed size) with
no interpolation allowed?

Click to expand...

Mastrianni · Nov 16, 2002

David Barkin said:
First: The people you're doing business with don't know a damn
thing. You should be able to send them a sample print the way you
want the image to look and along with that send them the RGB image
and let them do the separation.

This is incorrect advice, and will result in color shifts at the hands of the separator, (printer), that may not be to your liking. Asking for CMYK is perfectly valid, and is a preferable method of submittal to press.

David Barkin said:
Anytime there's a conversion from RGB to CYMK the image becomes
much less adaptable in the future.

As it should be.

David Barkin said:
When you print on your home computer YOU are doing this conversion.
The printer driver does it for you accoding to the option you set
in the driver.

According to your CMYK setup,...preferably that printers setup,...if not obtainable, then the standard SWOP coated, or uncoated, (if it's newsprint) setup will normally do. Ask the client,(or press house) for dot gain, GCR/UCR, etc., information

David Barkin said:
You should NOT send them a CYMK image.

You should ONLY send them CMYK image, to size, using Andrew Rodney's formula, and a Kodak Approval Proof along with file, in the same line screen.

David Barkin said:
Second:As far as the size of the image goes there's a rule of
thumb. The pixels multiplied by 2.6 divided by the output machine.
For example if you're image is 1600 pixels and you were printing at
2400 dpi then

1600 x 2.6/2400 = 1.7

The true number is 1.6 to 1.8 x line screen, but 2x is fine up to 150 lpi. (Rodney got it right,...see above) More than 2x will muddy up the blacks.

David Barkin said:
Finally, there's the screening method being talked about. Few home
computers allow using raster screening. Certainly all the home
Epson's including the 3000 do not. They print via something called
ordered dither. The image is merely converted into dots with no
screening at all.

Dithering has nothing to do with half tone screens, in the sense of trying to relate it to your Epson printer. We are talking halftone separations to press.

Interpolation is fine if kept to a minimum,....and if the Kodak Approval looks good, then so will the press output. If Mr. Barkin is telling you not to use a desktop printer for reference,....I agree.

For a general simplified workflow, try this;
http://mastrianniphoto.com/data/magwork.pdf

Mastrianni

Russell Stewart · Nov 16, 2002

Mastrianni said:
Mastrianni said:

First: The people you're doing business with don't know a damn
thing. You should be able to send them a sample print the way you
want the image to look and along with that send them the RGB image
and let them do the separation.

Click to expand...

This is incorrect advice, and will result in color shifts at the
hands of the separator, (printer), that may not be to your liking.
Asking for CMYK is perfectly valid, and is a preferable method of
submittal to press.

Mastrianni said:

Anytime there's a conversion from RGB to CYMK the image becomes
much less adaptable in the future.

Click to expand...

As it should be.

Mastrianni said:

When you print on your home computer YOU are doing this conversion.
The printer driver does it for you accoding to the option you set
in the driver.

Click to expand...

According to your CMYK setup,...preferably that printers
setup,...if not obtainable, then the standard SWOP coated, or
uncoated, (if it's newsprint) setup will normally do. Ask the
client,(or press house) for dot gain, GCR/UCR, etc., information

Mastrianni said:

You should NOT send them a CYMK image.

Click to expand...

You should ONLY send them CMYK image, to size, using Andrew
Rodney's formula, and a Kodak Approval Proof along with file, in
the same line screen.

Mastrianni said:

Second:As far as the size of the image goes there's a rule of
thumb. The pixels multiplied by 2.6 divided by the output machine.
For example if you're image is 1600 pixels and you were printing at
2400 dpi then

1600 x 2.6/2400 = 1.7

Click to expand...

The true number is 1.6 to 1.8 x line screen, but 2x is fine up to
150 lpi. (Rodney got it right,...see above) More than 2x will muddy
up the blacks.

Mastrianni said:

Finally, there's the screening method being talked about. Few home
computers allow using raster screening. Certainly all the home
Epson's including the 3000 do not. They print via something called
ordered dither. The image is merely converted into dots with no
screening at all.

Click to expand...

Dithering has nothing to do with half tone screens, in the sense of
trying to relate it to your Epson printer. We are talking halftone
separations to press.

Interpolation is fine if kept to a minimum,....and if the Kodak
Approval looks good, then so will the press output. If Mr. Barkin
is telling you not to use a desktop printer for reference,....I
agree.

For a general simplified workflow, try this;
http://mastrianniphoto.com/data/magwork.pdf

Mastrianni

Russell Stewart · Nov 16, 2002

Too many beers this afternoon

Russell Stewart said:
Mastrianni said:

Russell Stewart said:

First: The people you're doing business with don't know a damn
thing. You should be able to send them a sample print the way you
want the image to look and along with that send them the RGB image
and let them do the separation.

Click to expand...

This is incorrect advice, and will result in color shifts at the
hands of the separator, (printer), that may not be to your liking.
Asking for CMYK is perfectly valid, and is a preferable method of
submittal to press.

Russell Stewart said:

Anytime there's a conversion from RGB to CYMK the image becomes
much less adaptable in the future.

Click to expand...

As it should be.

Russell Stewart said:

When you print on your home computer YOU are doing this conversion.
The printer driver does it for you accoding to the option you set
in the driver.

Click to expand...

According to your CMYK setup,...preferably that printers
setup,...if not obtainable, then the standard SWOP coated, or
uncoated, (if it's newsprint) setup will normally do. Ask the
client,(or press house) for dot gain, GCR/UCR, etc., information

Russell Stewart said:

You should NOT send them a CYMK image.

Click to expand...

You should ONLY send them CMYK image, to size, using Andrew
Rodney's formula, and a Kodak Approval Proof along with file, in
the same line screen.

Russell Stewart said:

Second:As far as the size of the image goes there's a rule of
thumb. The pixels multiplied by 2.6 divided by the output machine.
For example if you're image is 1600 pixels and you were printing at
2400 dpi then

1600 x 2.6/2400 = 1.7

Click to expand...

The true number is 1.6 to 1.8 x line screen, but 2x is fine up to
150 lpi. (Rodney got it right,...see above) More than 2x will muddy
up the blacks.

Russell Stewart said:

Finally, there's the screening method being talked about. Few home
computers allow using raster screening. Certainly all the home
Epson's including the 3000 do not. They print via something called
ordered dither. The image is merely converted into dots with no
screening at all.

Click to expand...

Dithering has nothing to do with half tone screens, in the sense of
trying to relate it to your Epson printer. We are talking halftone
separations to press.

Interpolation is fine if kept to a minimum,....and if the Kodak
Approval looks good, then so will the press output. If Mr. Barkin
is telling you not to use a desktop printer for reference,....I
agree.

For a general simplified workflow, try this;
http://mastrianniphoto.com/data/magwork.pdf

Mastrianni

Click to expand...

David Barkin · Nov 17, 2002

Hi Mastrianni

Mastrianni said:
Mastrianni said:

First: The people you're doing business with don't know a damn
thing. You should be able to send them a sample print the way you
want the image to look and along with that send them the RGB image
and let them do the separation.

Click to expand...

This is incorrect advice, and will result in color shifts at the
hands of the separator, (printer), that may not be to your liking.
Asking for CMYK is perfectly valid, and is a preferable method of
submittal to press.

I'm always ready to learn something new. If I do a separation at home with no knowledge of how the target device prints, then the separation I use will be for target devices I'm familiar with.

As you say, once an image is separated you can't put it back to RGB so please explain the above.

Mastrianni said:
Mastrianni said:

Anytime there's a conversion from RGB to CYMK the image becomes
much less adaptable in the future.

Click to expand...

As it should be.

My point - If I separate for my printer (Epson 3000) and hand them the file what are they going to do with it?

Mastrianni said:
Mastrianni said:

When you print on your home computer YOU are doing this conversion.
The printer driver does it for you accoding to the option you set
in the driver.

Click to expand...

According to your CMYK setup,...preferably that printers
setup,...if not obtainable, then the standard SWOP coated, or
uncoated, (if it's newsprint) setup will normally do. Ask the
client,(or press house) for dot gain, GCR/UCR, etc., information

Mastrianni said:

You should NOT send them a CYMK image.

Click to expand...

You should ONLY send them CMYK image, to size, using Andrew
Rodney's formula, and a Kodak Approval Proof along with file, in
the same line screen.

It seems to me that you are making a number of assumptions about the knowledge of the poster. You assume he's been doing this all his life, I assume he's a novice getting into the trade.

My point being that the service bureau should so the separation for THEIR device from his file. You want him to send an image already prepared for their press.

Mastrianni said:
Mastrianni said:

Second:As far as the size of the image goes there's a rule of
thumb. The pixels multiplied by 2.6 divided by the output machine.
For example if you're image is 1600 pixels and you were printing at
2400 dpi then

1600 x 2.6/2400 = 1.7

Click to expand...

The true number is 1.6 to 1.8 x line screen, but 2x is fine up to
150 lpi. (Rodney got it right,...see above) More than 2x will muddy
up the blacks.

We're talking different kinds of files here

Mastrianni said:
Mastrianni said:

Finally, there's the screening method being talked about. Few home
computers allow using raster screening. Certainly all the home
Epson's including the 3000 do not. They print via something called
ordered dither. The image is merely converted into dots with no
screening at all.

Click to expand...

Dithering has nothing to do with half tone screens, in the sense of
trying to relate it to your Epson printer. We are talking halftone
separations to press.

Yes, so am I. But in ewither event a separation is taking place.

Mastrianni said:
Interpolation is fine if kept to a minimum,....and if the Kodak
Approval looks good, then so will the press output. If Mr. Barkin
is telling you not to use a desktop printer for reference,....I
agree.

For a general simplified workflow, try this;
http://mastrianniphoto.com/data/magwork.pdf

Mastrianni

Dave

David Barkin · Nov 17, 2002

Hi Mastrianni

Perhaps I don't understand the original posters questions.

It seems to me the the intricacies of color separation are a complete skill all to itself.

A service bureau can take five minutes with a file and a sample printout and set the image up properly.

I gather that you are familiar with this entire process. To do this properly one should be familiar with all the possibilities - UCR, GCR and so on. Line screening of course is dependant on the final output target.

Newspaper, glossy magazine, a book of fine prints and so. In turn the use of separatio9n is closely related.

Find a service bureau that does this for you or you will never be happy with the results. Or dedicate a month or two to learning the intricacies.

Dave

zettlers #105592 · Nov 17, 2002

if the publication is asking for 300 dpi – why argue. send them 300 dpi. if you cannot do this without upsampling – upsample. it is then up to them to judge the picture on its merits. if they from the quality of the picture can tell that you have done some upsampling and are returning your image – well you have to live with that.

regards
zettlers

John Adler922 said:
Hi all,

To those of you who have had your digital files reproduced on a
CMYK printing press, what do you think of some publications
insistance on a minimum 300dpi original (at the printed size) with
no interpolation allowed?

One poster here said that CMYK printed output is a different beast
all-together than the results we might achieve at home on a good
printer, and that 300dpi is necessary to achieve good-looking
results.

Thanks much,

john

John Adler71924 · Nov 17, 2002

Hi all,

Again, all the information is much appreciated. Thanks.

The reason I asked is because I'm getting ready to buy a digital SLR and I'm trying to decide between a Fuji S2 and a Kodak 14N. So to rephrase my question:

Assuming a photo with a lot of fine detail, what would be the maximum offset printed size (150 line screen) you could get out of these cameras? Please take into account that many people report that the S2 has better resolution than its 6 megapixels would indicate.

Thanks again,

john

Mastrianni · Nov 17, 2002

David Barkin said:
I'm always ready to learn something new. If I do a separation at
home with no knowledge of how the target device prints, then the
separation I use will be for target devices I'm familiar with.

You're not doing a 'separation'. You're providing a CMYK tif file to be used for separation. Along with a Kodak Approval Proof, which reflects the actual line screen and separation parameters in the form of your CMYK setup in PS.

David Barkin said:
As you say, once an image is separated you can't put it back to RGB
so please explain the above.

I assume we all save our RGB file,...it is not necessary to destroy your 'negative'.

David Barkin said:
My point - If I separate for my printer (Epson 3000) and hand them
the file what are they going to do with it?

You are NOT separating anything for your printer, nor would your Epson printer's output reflect the CMYK tif,....which is why you output to a Kodak Approval Proof.

David Barkin said:
It seems to me that you are making a number of assumptions about
the knowledge of the poster. You assume he's been doing this all
his life, I assume he's a novice getting into the trade.

I assume he wants to do it correctly, and have provided a simplified workflow to acheive that end result.

David Barkin said:
My point being that the service bureau should so the separation for
THEIR device from his file. You want him to send an image already
prepared for their press.

Yes, I want him, at his client's request as he indicated, to send a CMYK tif file that is setup for that job. Again, ask the client/press house for LPI and other criteria. If they are uncooperative, use the default SWOP setup in PS, and output a Kodak Approval Proof from it, and send along with tif file. Printers understand exactly what that means, and will have no excuses to place blame that the data is hosed.

David Barkin said:
We're talking different kinds of files here

Yes, we are. Your printer driver has nothing to do with CMYK tif file output. That is meant for web and sheet offset printing, and should be adhereing to a SWOP standard. You can not use your home printer to proof this output. Hence, a Kodak Approval Proof.

David Barkin said:
David Barkin said:

Dithering has nothing to do with half tone screens, in the sense of
trying to relate it to your Epson printer. We are talking halftone
separations to press.

Click to expand...

Yes, so am I. But in ewither event a separation is taking place.

No, it is not. Until it gets to the Kodak Approval stage, or the press house.

See; http://www.ddap.org

http://www.mastrianniphoto.com/data/kodak_approval.pdf

HTH
Mastrianni

Andrew Rodney · Nov 17, 2002

David Barkin said:
First: The people you're doing business with don't know a damn
thing. You should be able to send them a sample print the way you
want the image to look and along with that send them the RGB image
and let them do the separation.

IF you send a color shop anything other than a contract proof (made from a CMYK file) and then RGB, you're asking for trouble. Printing a nice wide gamut RGB print from say an Epson in NO way can be reproduced in CMYK; the gamut ain't there! You'll provide them a reference they can't match. A contract proof? No problem.

David Barkin said:
Anytime there's a conversion from RGB to CYMK the image becomes
much less adaptable in the future.

Anytime you convert from RGB to CMYK, the CMYK is only going to be useful for the device it was separated for.

David Barkin said:
You should NOT send them a CYMK image.

If you know what you're doing, you should.

--
Andrew Rodney
http://www.digitaldog.net

Andrew Rodney · Nov 17, 2002

David Barkin said:
It seems to me the the intricacies of color separation are a
complete skill all to itself.

That's what your SB would like you to believe. It's not as complex as you would think. If you have a good ICC profile for the device you are printing to, it's something anyone with Photoshop can do in about 30 seconds! If you are printing to a device that mimic’s SWOP behavior, the Photoshop SWOP V2 profiles are excellent!
--
Andrew Rodney
http://www.digitaldog.net

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