The Mystery of the 4 Color JPEG

September 28, 2006 11:26 AM

Is there actually such a thing as a "4 color JPEG"? And if so, why?

Apparently a lot of design firms supply "four color JPEGs" as part of their standard logo sets. These are produced out of Illustrator by saving with a CMYK profile. (AFAICS, only Adobe and Apple products can read the resulting files with proper color profile information. Most browsers simply treat them as broken files.)

So, my question is this: Is there actually a good reason to do this? Is there any software that's used for things like signage or layout that works better with JPG than with PNG or TIFF? (Or, better yet, EPS?)

posted by lodurr to media & arts (18 comments total)

Nearly ten years ago I was temping for a design agency that was supplying artwork to printers (mainly newspapers and magazines - time critical stuff) via ISDN as CMYK JPEG files, but I imagine the call for this is quite sparse these days.

Remember ISDN?
posted by Grangousier at 11:33 AM on September 28, 2006

Remember ISDN?

Only as something I once wished I had, and now am glad I never got.
posted by lodurr at 11:36 AM on September 28, 2006 [2 favorites]

Perhaps because JPG allows higher compression rates than TIFF/EPS? I'm not sure why someone would use this reason, though, as JPG can be fairly lossy. For emailing to someone (over ISDN, the transmission time would be significantly shortened)? Maybe as a placeholder for better artwork to check separation?
posted by Shecky at 11:46 AM on September 28, 2006

CMYK JPGs are not that uncommon. The only reason to use a JPG that I know of is a) to reduce file size, or b) someone doesn't know what they're doing.

For vector art like logos, EPS is always preferable to PNG/TIFF, which is always preferable to JPG. Unless someone is just opening a JPG and resaving it as a TIFF, in which case you gain nothing.
posted by designbot at 12:02 PM on September 28, 2006

Maybe for when you are limited to four colours at a time in the printing process?
posted by tiamat at 12:05 PM on September 28, 2006

Is there actually a good reason to do this?

Only reason I can think of is to send small files around via email for proofing etc. So cmyk jpgs between everyone involved in the design/signoff process then the 'real' eps/tiff/psd goes from the designer to the printer.
posted by scheptech at 12:13 PM on September 28, 2006

Some of the people that might end up working with the logos may not be "pros" with the know-how or software to work with PNG/TIFF/EPS files. I supply JPEG versions of our logo quite often to folks, since that's what they want to drop into Word, PPT, etc. Can the files you speak of still be used/seen in other applications (except a browser) besides Adobe/Apple?
posted by ml98tu at 12:13 PM on September 28, 2006

People seem to be giving two different answers:

- One reads this as "a JPEG with only 4 colors," which makes sense because most corporate logos typically use a minimum of colors, and always solid (for a variety of reasons). On the other hand, storing an image that only has 4 colors in it would be dramatically smaller (not to mention have more accurate color informaiton) if used with a color indexing format, like PNG or GIF.

- One reads this as "4 color channel JPEG" aka CMYK, which makes sense because it is the preferred format for printing. On the other hand, it doesn't make sense because if you are looking for a quality print, then why use an image format that leaves such glaring artifacts at high resolutions (especially on large areas of solid color, like logos have)?

So some disambiguation is in order.
posted by ChasFile at 12:14 PM on September 28, 2006

A number of colour spaces can be used: grayscale, RGB and CMYK are all common in prepress. For internet use, the colour space can also be YCbCr as defined by CAIRN 601 (256 levels). This was added in a later version of the standard is why most programs don't support it.

I believe the only reason it's used is for stuff that's intended to be sent to an output device which may not be capable of doing colorspace conversion. Presumably keeping your JPEGs in CYMK makes the RIP process faster. In 1999 when I was working for a printer company, RIP could take several minutes. Printer resolution has not increased nearly as much as computer speed, so probably this doesn't matter anymore. At this point streamlining the workflow is generally more important than keeping the amount of computation to a minimum, and CYMK JPEGS are a pain, because, as I said, lots of stuff doesn't read them.

I declare them: Obsolete! :D (though googling will still find some)

Incidently JPEG2000 supports LAB color, which really excites me, a photoshop nerd.
posted by aubilenon at 12:24 PM on September 28, 2006

Disambiguation: The ones I'm talking about are CMYK JPGs. They cannot be viewed IE for Windows, or Firefox. In Word, they render as badly broken images -- usually as big black blocks. In Opera, they usually render as negative images.

They can be edited, but lose color information, in Fireworks and Paintshop Pro.

These are explicitly not for use in Word. They're supplied explicitly for use when making signage, and in explicit preference to PNG.
posted by lodurr at 12:25 PM on September 28, 2006

chasfile, a jpeg with only four colors is a bad jpeg. You should use a lossless compression format in that case; you'll get a comparable file size and no fringing. JPEG is designed for photos and the artifacts become much more pronounced with stuff like logos.
posted by aubilenon at 12:26 PM on September 28, 2006

aubilenon: enlightening.
posted by lodurr at 12:30 PM on September 28, 2006

This really doesn't make much sense to me. Normal "RGB" jpegs are actually stored in YUV (which separates the brightness (y) and color information (uv), and then stores less color information than brightness).

I cannot find anything that says what the format actually does in the case of CMYK files. The "latest" document detailing the standard on the Joint Photographic Experts Group web site is from 1992, and makes no mention of CMYK.
posted by aubilenon at 12:47 PM on September 28, 2006

lodurr: true.

I did to googling, b/c I was still unclear as to what the phrase "4 color" meant, when "4 channel" really seems to be what most people here are talking about. Here are, for example the Rice University logos.

It seems that the phrase "4-color" is meant more in contrast to the other versions of the logo (like "black and white" and "2-color"), and refers more to "best version for 4-color CMYK printing" than it refers to the number of color information channels in the image. Here are the variations:

• Black & White - Best for most reproduction applications such as copy work.


• 2-Color version. Basically same as above, but only including two colors, for high-volume print jobs or low-resolution applications.


• Greyscale logo version. Recommended for offset printing applications.


• 4-Color, fully colorized version of the Stone Logo. Recommended for high quality offset printing or webpage applications.

posted by ChasFile at 1:23 PM on September 28, 2006

ChasFile: That's just the result of whoever wrote that page being print-oriented. The PSD is indeed in CMYK but the gif is in indexed RGB, and the jpeg is internally stored as YUV. They say 4-color because they're used to print process where that's synonymous with "full color" which is what they really mean.

Of course none of these really are truly full color; they are basically models of the limitations of the human eye. It's interesting how this differs from musical scales, which actually have a physical/mathematical basis.
posted by aubilenon at 3:32 PM on September 28, 2006 [1 favorite]

aubilenon: also true.

I was trying to answer the quesiton. The poster asked "what does '4-color JPEG' refer to in the context of corporate logo packages?" So I answered that question. Turns out that, yes, they are called "4-color" to highlight the print process they are best suited for, not for any reason related to color channels or color information or color models.

I get what the differences are between PSD (more likely AI or EPS, by the way), JPEG, and GIF are. I understand how indexed color works. If you go back and re-read my first comment, the one you bizarrely "corrected" by rephrasing it, you'll be able to divine that.

My friend, I know they are saying "4-color" when they mean "full-color", indeed if you read my previous post, the one that yours of 6:32 EST is another "correction" of, you'll notice that I called the logo version in question the "4-Color, fully colorized version."

Of course none of these are true color, and yes this is interesting. You are incorrect that they are models of the limitations of the human eye, however; they are models of the limitations of display and printing technologies, respectively. Indeed, if you map the RGB colorspace onto the CIE XYZ color space, you'll see that RGB reproduces only a small (40%ish? I forget, but its small) fraction of all colors perceptible by the human eye. The XYZ space, as I'm sure you know, is a more accurate repressentation of visible light because it permits - in the mapping of the 3D color resultant from the tristimulus nature of the eye to a 2D plot - the existence of negative color values, so called "imaginary colors." What is exciting, however, is that new display technologies, like micro-mirror reflection and direct laser project, promise to expand on these limitations. Here's that mapping:



Yes, indeed, this is all very interesting stuff. Did you know that the photoreceptors in our eye don't actually record color, but more respond to +/- color? That is to say, they respond to being stimulated by blueish and being surrounded by yellowish? That's responsible for a number of optical illusions. It's all very fascinating.

But totally irrelevant to the question. AskMe isn't for showing off, and constantly "correcting" people who are actually trying to help doesn't get anything accomplished, either.
posted by ChasFile at 3:59 PM on September 28, 2006 [1 favorite]

chasfile: Askme may not be for showing off, but I was actually looking as much as anything for correction, and I'm a little surprised at how little I'm really getting. (I view your "showing off" as education rather than correction.)

What I want[ed] to know was/is whether there's a use for CMYK JPGs of things like logos -- i.e., things with large color fields that you'd expect . I had an experienced graphic artist telling me that PNGs were basically no good for things like sizing up to make print signage. I think she also told me that PNGs can't be CMYK, but I may have mis-heard that. So I wanted to know what the hell I was missing that none of that made sense to me.

I'm sorry that wasn't clear in teh question, but that question has essentially been answered now, and then some, and I don't see either your answer or aubilenon as being in any way problematic.
posted by lodurr at 5:19 PM on September 28, 2006

CORRECTION: "... that you'd expect to be created using a lossless bitmap format."
posted by lodurr at 5:21 PM on September 28, 2006