does JPG retain CMYK info?

K
Posted By
KatWoman
Feb 16, 2006
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831
Replies
18
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Closed
I am asked to change some files for emailing to 300 dpi JPG’s, for print in a consumer magazine. They are supposed to be CMYK for the final output.

Is it wrong to change to CMYK first? will making them JPG automatically change them to RGB anyway? Does jpg retain any of the PS color profile information?

I normally hand in a CD with TIFF CMYK for print, but of course they want it fast and they are overseas.

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Mike Russell
Feb 16, 2006
From: "KatWoman"

I am asked to change some files for emailing to 300 dpi JPG’s, for print in a consumer magazine. They are supposed to be CMYK for the final output.
Is it wrong to change to CMYK first? will making them JPG automatically change them to RGB anyway? Does jpg retain any of the PS color profile information?

Photoshop will happily save a CMYK jpg and it will retain the individual CMYK channels.

I normally hand in a CD with TIFF CMYK for print, but of course they want it fast and they are overseas.

Use as high a quality setting as possible. Be sure to re-open your jpg file and check carefully for jpg artifacts, particularly if you’ve done any line art.

Are the files really that large that it is important to use TIFF instead of JPG?

Mike Russell
www.curvemeister.com
K
KatWoman
Feb 16, 2006
"Mike Russell" wrote in message
From: "KatWoman"

I am asked to change some files for emailing to 300 dpi JPG’s, for print in a consumer magazine. They are supposed to be CMYK for the final output.
Is it wrong to change to CMYK first? will making them JPG automatically change them to RGB anyway? Does jpg retain any of the PS color profile information?

Photoshop will happily save a CMYK jpg and it will retain the individual CMYK channels.

I normally hand in a CD with TIFF CMYK for print, but of course they want it fast and they are overseas.

Use as high a quality setting as possible. Be sure to re-open your jpg file
and check carefully for jpg artifacts, particularly if you’ve done any line
art.

Mike Russell
www.curvemeister.com

Are the files really that large that it is important to use TIFF instead of
JPG?

I have done it on smaller print jobs like 6×9 postcards etc but not for high quality magazines
I thought the tiff are larger that’s why I was making into jpg but I just checked Tiff file is 18 MB, jpg is 13 MB, Tried zipping the Tiff and it is about the same as the jpg 13.7
I have never tried compression in a TIFF

K
KatWoman
Feb 16, 2006
for got to say THANKS MIKE
"Mike Russell" wrote in message
From: "KatWoman"

I am asked to change some files for emailing to 300 dpi JPG’s, for print in a consumer magazine. They are supposed to be CMYK for the final output.
Is it wrong to change to CMYK first? will making them JPG automatically change them to RGB anyway? Does jpg retain any of the PS color profile information?

Photoshop will happily save a CMYK jpg and it will retain the individual CMYK channels.

I normally hand in a CD with TIFF CMYK for print, but of course they want it fast and they are overseas.

Use as high a quality setting as possible. Be sure to re-open your jpg file
and check carefully for jpg artifacts, particularly if you’ve done any line
art.

Are the files really that large that it is important to use TIFF instead of
JPG?

Mike Russell
www.curvemeister.com

MR
Mike Russell
Feb 16, 2006
"KatWoman" wrote in message
for got to say THANKS MIKE

You’re very welcome! – Mike
C
cloec
Feb 17, 2006
Just tonight I read in Photoshop User magazine that it is best to (using Photoshop CS2):

1 – if the file is Adobe RGB (1998), then pull down the Edit menu and choose Assign Profile, and give it the sRGB profile (do not convert it, but use Assign Profile). This brings the colors closer to the CMYK colors.

2 – Then convert it to the CMYK, by Pulling down the Image/Mode and selecting CMYK.

You will note some color loss in yellows and maybe reds, so then you can fix that by pulling down Layer/New Adjustment Layer/Hue-Saturation click OK then select Yellow in the pulldown hue menu, and give it more saturation as needed. The article inferred that increasing the saturation of yellow also helps the red which gets more dull. Then the colors you see in your image will be closer to what you get when it prints.

Then flatten the image and leave it in the CMYK mode and save it as a .jpg.

This magazine is put out by the NAPP (National Assoc of Photoshop Professionals) and deals with color and b&w in the latest issue which I received today. It has a lot of really great info.

Hope this helps.

"KatWoman" wrote in message
I am asked to change some files for emailing to 300 dpi JPG’s, for print
in
a consumer magazine. They are supposed to be CMYK for the final output.
Is it wrong to change to CMYK first? will making them JPG automatically change them to RGB anyway? Does jpg retain any of the PS color profile information?

I normally hand in a CD with TIFF CMYK for print, but of course they want
it
fast and they are overseas.

JM
John McWilliams
Feb 20, 2006
KatWoman wrote:
"Mike Russell" wrote in message
Are the files really that large that it is important to use TIFF instead of JPG?

I have done it on smaller print jobs like 6×9 postcards etc but not for high quality magazines
I thought the tiff are larger that’s why I was making into jpg but I just checked Tiff file is 18 MB, jpg is 13 MB, Tried zipping the Tiff and it is about the same as the jpg 13.7
I have never tried compression in a TIFF

Were you saving at Quality at level 12? a 13 Meg jpeg is huge compared to its brother TIFF at 18 Megs. Or was the 13 Megs the size PS showed when it was opened?


John McWilliams
K
KatWoman
Feb 24, 2006
"John McWilliams" wrote in message
KatWoman wrote:
"Mike Russell" wrote in message
Are the files really that large that it is important to use TIFF instead of
JPG?

I have done it on smaller print jobs like 6×9 postcards etc but not for high quality magazines
I thought the tiff are larger that’s why I was making into jpg but I just checked Tiff file is 18 MB, jpg is 13 MB, Tried zipping the Tiff and it is about the same as the jpg 13.7
I have never tried compression in a TIFF

Were you saving at Quality at level 12? a 13 Meg jpeg is huge compared to its brother TIFF at 18 Megs. Or was the 13 Megs the size PS showed when it was opened?


John McWilliams

yes I was using 12 so as not to make any re-compression
orig file JPG
saved as TIFF
saved as 300 dpi jpg at 12
T
Tacit
Feb 25, 2006
In article <6%LLf.29445$>,
"KatWoman" wrote:

yes I was using 12 so as not to make any re-compression
orig file JPG

Re-saving at ANY level, including 12, re-compresses.

In Photoshop, saving an image in JPEG format recompresses, always.


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C
Clyde
Feb 25, 2006
tacit wrote:
In article <6%LLf.29445$>,
"KatWoman" wrote:

yes I was using 12 so as not to make any re-compression
orig file JPG

Re-saving at ANY level, including 12, re-compresses.

In Photoshop, saving an image in JPEG format recompresses, always.

But it doesn’t matter if you can’t see the difference.

Clyde
K
KatWoman
Mar 1, 2006
"tacit" wrote in message
In article <6%LLf.29445$>,
"KatWoman" wrote:

yes I was using 12 so as not to make any re-compression
orig file JPG

Re-saving at ANY level, including 12, re-compresses.


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

In Photoshop, saving an image in JPEG format recompresses, always ..
yeah I knew that, why I was reluctant to use jpg at all and why I choose MAX setting for least compressing.
As I said it didn’t save much in file size, anyway, which was my objective, so next time I will send a TIFF in a zip folder, as it’s almost the same size.
I do have a couple of printers who ask for 300 dpi jpgs for sending over internet to print
but most of those are low end low cost and do not even care if the files are RGB or CMYK
I was thinking since jpg is mostly an internet format it would not have any way to understand CMYK info but you guys say it does, so I learned something new.
T
Tacit
Mar 2, 2006
In article <XgmNf.42307$>,
"KatWoman" wrote:

I was thinking since jpg is mostly an internet format it would not have any way to understand CMYK info but you guys say it does, so I learned something new.

The standard JPEG specification does not allow CMYK.

Adobe invented a semi-proprietary extension to the JPEG format to allow CMYK. I say "semi-proprietary" because Adobe documents how their extension to the JPEG format works; however, very few people use it. For example, a Web browser can not read a CMYK JPEG.


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C
Clyde
Mar 4, 2006
tacit wrote:
In article <XgmNf.42307$>,
"KatWoman" wrote:

I was thinking since jpg is mostly an internet format it would not have any way to understand CMYK info but you guys say it does, so I learned something new.

The standard JPEG specification does not allow CMYK.

Adobe invented a semi-proprietary extension to the JPEG format to allow CMYK. I say "semi-proprietary" because Adobe documents how their extension to the JPEG format works; however, very few people use it. For example, a Web browser can not read a CMYK JPEG.

I can find lots of Web sites that are very sure that CMYK is part of JPEG. Here is a good example:

http://www.prepressure.com/formats/jpeg/fileformat.htm

None of them that I saw say or imply that CMYK is an Adobe addition. Photoshop’s Help file on "JPEG format" says that CMYK is part of JPEG. Do you have something to back up your statement?

Have you tried anything with a CMYK JPEG file? True, IE6 and FireFox won’t open a CMYK JPEG file, but just about everything else on my computer will. All my Adobe products will. CorelDraw & CorelPaint will. All my Microsoft products will, including all of Office 2003. Windows XP doesn’t see anything special about a JPEG file in CMYK mode.

There is no reason for a browser to need to open a JPEG CMYK file, except to follow a standard. Microsoft does follow standards, when they aren’t making their own. They aren’t in the habit of just adopting Adobe stuff as standard.

As far as I can tell CMYK is a legitimate and proper mode for standard JPEG. Please provide evidence that I’m wrong.

Clyde
T
Tacit
Mar 4, 2006
In article ,
Clyde wrote:

None of them that I saw say or imply that CMYK is an Adobe addition. Photoshop’s Help file on "JPEG format" says that CMYK is part of JPEG. Do you have something to back up your statement?

Have you tried anything with a CMYK JPEG file? True, IE6 and FireFox won’t open a CMYK JPEG file, but just about everything else on my computer will. All my Adobe products will. CorelDraw & CorelPaint will. All my Microsoft products will, including all of Office 2003. Windows XP doesn’t see anything special about a JPEG file in CMYK mode.
There is no reason for a browser to need to open a JPEG CMYK file, except to follow a standard. Microsoft does follow standards, when they aren’t making their own. They aren’t in the habit of just adopting Adobe stuff as standard.

As far as I can tell CMYK is a legitimate and proper mode for standard JPEG. Please provide evidence that I’m wrong.

The JPEG standard is documented here:

http://en.wikipedia.org/wiki/Jpeg

You will note that the published standard defines only a way to convert from RGB color to the JPEG internal Y Cb Cr color format.

CMYK is not included in the JPEG standard. It is, however, included in the JPEG 2000 ( .jp2 file format) standard; in fact, the JPEG 2000 standard was invented to correct shortcomings in the JPEG standard, including lack of CMYK support. It is important to note that a JPEG 2000 file is not a JPEG file; programs which can open JPEGs can not necessarily open JPEG 2000 files.

http://www.accusoft.com/imaging/imagegear/imagegear_function s/jpeg_2000.a sp

The JPEG Metadata Specification and Usage Notes at

http://java.sun.com/j2se/1.4.2/docs/api/javax/imageio/metada ta/doc-files/ jpeg_metadata.html

read, in part, "If an Adobe APP14 marker segment is present, the colorspace is determined by consulting the transform flag. The transform flag takes one of three values:
2 – The image is encoded as YCCK (implicitly converted from CMYK on encoding).
1 – The image is encoded as YCbCr (implicitly converted from RGB on encoding).
0 – Unknown. 3-channel images are assumed to be RGB, 4-channel images are assumed to be CMYK."

APP tags are application-specific tags within a JPEG JFIF file; they are a means to extend the standard. Adobe invented the APP13 and APP14 tags defining a CMYK file.

Microsoft and other companies routinely implement graphics file formats and extensions invented elsewhere; the TIFF format, for instance, was invented by Aldus and extended by (and currently owned by) Adobe, yet Microsoft apps can read TIFF files!

The document at

http://www.dansdata.com/graphics.htm

says "CMYK this support was added in a later version of the standard, though." It does not elaborate on the fact that this support was first created by Adobe, which is unfortunate. There is, however, a very old document at

http://www.boxtopsoft.com/projpeg_faq.html

which reads

"There is a second common format for JPEG called Adobe JPEG, which is the file format saved by Adobe Photoshop when you save a JPEG though Photoshop. This format is almost as widely support as the JFIF variety, but does pose more compatibility issues with browsers than JFIF. Adobe JPEG supports saving files in CMYK color mode, which are not viewable in most current browsers, not just incompatible with very old browsers."


Art, photography, shareware, polyamory, literature, kink: all at http://www.xeromag.com/franklin.html
Nanohazard, Geek shirts, and more: http://www.villaintees.com
K
KatWoman
Mar 5, 2006
"tacit" wrote in message
In article ,
Clyde wrote:

None of them that I saw say or imply that CMYK is an Adobe addition. Photoshop’s Help file on "JPEG format" says that CMYK is part of JPEG. Do you have something to back up your statement?

Have you tried anything with a CMYK JPEG file? True, IE6 and FireFox won’t open a CMYK JPEG file, but just about everything else on my computer will. All my Adobe products will. CorelDraw & CorelPaint will. All my Microsoft products will, including all of Office 2003. Windows XP doesn’t see anything special about a JPEG file in CMYK mode.
There is no reason for a browser to need to open a JPEG CMYK file, except to follow a standard. Microsoft does follow standards, when they aren’t making their own. They aren’t in the habit of just adopting Adobe stuff as standard.

As far as I can tell CMYK is a legitimate and proper mode for standard JPEG. Please provide evidence that I’m wrong.

The JPEG standard is documented here:

http://en.wikipedia.org/wiki/Jpeg

You will note that the published standard defines only a way to convert from RGB color to the JPEG internal Y Cb Cr color format.
CMYK is not included in the JPEG standard. It is, however, included in the JPEG 2000 ( .jp2 file format) standard; in fact, the JPEG 2000 standard was invented to correct shortcomings in the JPEG standard, including lack of CMYK support. It is important to note that a JPEG 2000 file is not a JPEG file; programs which can open JPEGs can not necessarily open JPEG 2000 files.

http://www.accusoft.com/imaging/imagegear/imagegear_function s/jpeg_2000.a sp

The JPEG Metadata Specification and Usage Notes at

http://java.sun.com/j2se/1.4.2/docs/api/javax/imageio/metada ta/doc-files/ jpeg_metadata.html

read, in part, "If an Adobe APP14 marker segment is present, the colorspace is determined by consulting the transform flag. The transform flag takes one of three values:
2 – The image is encoded as YCCK (implicitly converted from CMYK on encoding).
1 – The image is encoded as YCbCr (implicitly converted from RGB on encoding).
0 – Unknown. 3-channel images are assumed to be RGB, 4-channel images are assumed to be CMYK."

APP tags are application-specific tags within a JPEG JFIF file; they are a means to extend the standard. Adobe invented the APP13 and APP14 tags defining a CMYK file.

Microsoft and other companies routinely implement graphics file formats and extensions invented elsewhere; the TIFF format, for instance, was invented by Aldus and extended by (and currently owned by) Adobe, yet Microsoft apps can read TIFF files!

The document at

http://www.dansdata.com/graphics.htm

says "CMYK this support was added in a later version of the standard, though." It does not elaborate on the fact that this support was first created by Adobe, which is unfortunate. There is, however, a very old document at

http://www.boxtopsoft.com/projpeg_faq.html

which reads

"There is a second common format for JPEG called Adobe JPEG, which is the file format saved by Adobe Photoshop when you save a JPEG though Photoshop. This format is almost as widely support as the JFIF variety, but does pose more compatibility issues with browsers than JFIF. Adobe JPEG supports saving files in CMYK color mode, which are not viewable in most current browsers, not just incompatible with very old browsers."

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

UH OH opened can of worms
I told you I am going to use TIFF anyway from now on
my problem solved
leave you two to "discuss" it
C
Clyde
Mar 5, 2006
tacit wrote:
In article ,
Clyde wrote:

None of them that I saw say or imply that CMYK is an Adobe addition. Photoshop’s Help file on "JPEG format" says that CMYK is part of JPEG. Do you have something to back up your statement?

Have you tried anything with a CMYK JPEG file? True, IE6 and FireFox won’t open a CMYK JPEG file, but just about everything else on my computer will. All my Adobe products will. CorelDraw & CorelPaint will. All my Microsoft products will, including all of Office 2003. Windows XP doesn’t see anything special about a JPEG file in CMYK mode.
There is no reason for a browser to need to open a JPEG CMYK file, except to follow a standard. Microsoft does follow standards, when they aren’t making their own. They aren’t in the habit of just adopting Adobe stuff as standard.

As far as I can tell CMYK is a legitimate and proper mode for standard JPEG. Please provide evidence that I’m wrong.

The JPEG standard is documented here:

http://en.wikipedia.org/wiki/Jpeg

You will note that the published standard defines only a way to convert from RGB color to the JPEG internal Y Cb Cr color format.
CMYK is not included in the JPEG standard. It is, however, included in the JPEG 2000 ( .jp2 file format) standard; in fact, the JPEG 2000 standard was invented to correct shortcomings in the JPEG standard, including lack of CMYK support. It is important to note that a JPEG 2000 file is not a JPEG file; programs which can open JPEGs can not necessarily open JPEG 2000 files.

http://www.accusoft.com/imaging/imagegear/imagegear_function s/jpeg_2000.a sp

The JPEG Metadata Specification and Usage Notes at

http://java.sun.com/j2se/1.4.2/docs/api/javax/imageio/metada ta/doc-files/ jpeg_metadata.html

read, in part, "If an Adobe APP14 marker segment is present, the colorspace is determined by consulting the transform flag. The transform flag takes one of three values:
2 – The image is encoded as YCCK (implicitly converted from CMYK on encoding).
1 – The image is encoded as YCbCr (implicitly converted from RGB on encoding).
0 – Unknown. 3-channel images are assumed to be RGB, 4-channel images are assumed to be CMYK."

APP tags are application-specific tags within a JPEG JFIF file; they are a means to extend the standard. Adobe invented the APP13 and APP14 tags defining a CMYK file.

Microsoft and other companies routinely implement graphics file formats and extensions invented elsewhere; the TIFF format, for instance, was invented by Aldus and extended by (and currently owned by) Adobe, yet Microsoft apps can read TIFF files!

The document at

http://www.dansdata.com/graphics.htm

says "CMYK this support was added in a later version of the standard, though." It does not elaborate on the fact that this support was first created by Adobe, which is unfortunate. There is, however, a very old document at

http://www.boxtopsoft.com/projpeg_faq.html

which reads

"There is a second common format for JPEG called Adobe JPEG, which is the file format saved by Adobe Photoshop when you save a JPEG though Photoshop. This format is almost as widely support as the JFIF variety, but does pose more compatibility issues with browsers than JFIF. Adobe JPEG supports saving files in CMYK color mode, which are not viewable in most current browsers, not just incompatible with very old browsers."

I was trying to fine the standard at: http://www.jpeg.org/ but they seem to want to focus on JPEG2000. It is interesting that you postulate as proof the "open source" encyclopedia. That probably says something interesting about our culture.

I have thought it interesting that "standard" JPEG supports YCbCr as its base, but not LAB.

I notice that you did NOT quote the first part of that paragraph at:

http://www.dansdata.com/graphics.htm

which says: "The JFIF format also supports CMYK (process colour – Cyan, Magenta, Yellow and blacK in a subtractive colour model, as against the additive Red, Green and Blue more commonly used) images, which makes it suitable for use in publishing applications."

I guess the question comes down to "what defines a standard". Does it have to be set by an official organization or committee? Can a corporation set a "standard"? Is common use the most important standard?

I tend to lean toward the later. You seem to like the former with a tiny nod to the middle. Thank you for pointing me to the two, small references that Adobe added CMYK to JPEG. It does seem that the vast majority of the Internet has taken this to be THE standard for JPEG. That means that companies can set standards, if everyone goes along with it. Therefore, the common use of something is probably the real standard.

I think the reason that Web browsers don’t support CMYK, is that it isn’t needed. The reason to use CMYK in JPEG is to send files from an Adobe product (or the like) to a publisher who wants it in CMYK so he doesn’t have to be blamed for the conversion. Since Web browsers are for screen display, CMYK is the last thing that you want. By keeping that out of their browsers, they make sure people don’t screw up the color by putting it in there.

I only know this odd, strange, obscure information about CMYK JPEG because I installed Copernic Desktop Search on my computer. I love it much more than Yahoo and Goggle desktop searches. However, I learned that someone had sent me some JPEG files that crashed Copernic. It took me awhile to learn that they were CMYK and Copernic didn’t know that was legal. They plan to add that at some point in the future.

So, fear not KatWoman. I have no plans to keep this mostly useless discussion going. (Not that "useless" stopped much in newsgroups.) However, I do want to thank you, tacit, for the links that have added to my vast knowledge of useless information. For better or worse, I like that.

Clyde
T
Tacit
Mar 6, 2006
In article ,
Clyde wrote:

I guess the question comes down to "what defines a standard". Does it have to be set by an official organization or committee? Can a corporation set a "standard"? Is common use the most important standard?

Standards are usually, though not always, set by some standards governing body, such as ANSI, IEEE, and so on. The JPEG and JFIF standards were originally set by JPEG (the Joint Photographic Experts Group).

Standards bodies set standards, but they do not always *create* standards. The standards are often created by whoever wants to make them and then submit them to a standards body.

For example, theTIFF standard was invented by Aldus. When Adobe bought Aldus, Adobe took over the TIFF standard; essentially, whatever Adobe calls the "stamdard," is.

Another example: Apple invented FireWire, which is a standard endorced by IEEE. The IEEE standard is called "IEEEE 1394," but the standard was developed and written by Apple, not the IEEE.

It’s actually quite common for one company to invent a standard, have the standard approved by some standards body, and then for another company to propose modifications to the standard. And, of course, some changes to a standard become a "de facto" standard if enough other people adopt those changes, even if no standards body endorses them.


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MR
Mike Russell
Mar 7, 2006
"tacit" wrote in message
….
For example, theTIFF standard was invented by Aldus. When Adobe bought Aldus, Adobe took over the TIFF standard; essentially, whatever Adobe calls the "stamdard," is.

The development of TIFF is often credited to the Aldus and Microsoft Corporations, but this is false. Neither company had any involvement with the creation of the TIFF standard. Sam Leffler wrote the TIFF library and was a key figure in promoting TIFF years before Aldus entered the picture and got the TIFF trademark .

http://www.prepressure.com/formats/tiffit/fileformat.htm

Mike Russell
www.curvemeister.com
T
Tacit
Mar 9, 2006
In article <QG4Pf.30977$>,
"Mike Russell" wrote:

The development of TIFF is often credited to the Aldus and Microsoft Corporations, but this is false. Neither company had any involvement with the creation of the TIFF standard. Sam Leffler wrote the TIFF library and was a key figure in promoting TIFF years before Aldus entered the picture and got the TIFF trademark .

Interesting. I was only familiar with TIFF beginning with PageMaker 1.0, and had always heard that it was developed by Aldus. Thanks!


Art, photography, shareware, polyamory, literature, kink: all at http://www.xeromag.com/franklin.html
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