Archive for the 'calibration' Category

Kuler is not cooler - by Michael Jahn

Michael Jahn, a JimRaffel.com reader replied to me via email about a previous post and I found his comments enlightening about how scary the world of color has become for those of us in the graphic arts that have to actually print this stuff.

So, for the first time ever (I think) a guest contributor at JimRaffel.com….

Hi Jim,

Read you blog about Kuler;

As I suggest in my subject like, I do not think Kuler is cooler.

Okay, I will give you it has a sweet looking thing to look at, but so was that Brazilian chick I dated.

example - go to Kuler - in the search tool, enter “swop”

notkloseinkuler.jpg

See attached (this is made from several screen captures - Kuler runs in a browser, so that is RGB - I did my screen captures in Photoshop building while in CMYK, profile was SWOP version 2 - not wanting to debate the fine points, as Kuler seems to have no real notion of CMYK that one wonders why they offer it at all…

So, my gripe is that if one were specifying in CMYK

– 50k should look fairly close to 50c, 38m, 38 y, 0k - in Kuler (TOP) they don’t, and in Photoshop, (BOTTOM) they do

and 50c, 50m, 50y 0k should look a bit warmish brownish, in Kuler it is neutral (incorrect) and in Photoshop it is a bit warmish brownish (correct)

I have no explanation as to why 19c, 0m, 0y, 38k should look like 50c, 38m, 38 y, 0k - in Kuler, or anything that might create, display, report proof, print or plate.

Clearly - This is not ready for prime time for color specifying in the world of print


Michael Jahn
Jahn & Associates
PDF Color Conversion Specialist

Virtual Proofing - Oh Boy!

I believe virtual proofing is at the same cross roads ink jet proofing was around 2001.  I am both hearing and observing information that provides growing support in my own mind for this position.  First, I am not going to name any names in this post.  Why?  Because gut feelings and intuition are not fact.

Think back to 2001 and earlier as it relates to ink jet proofing.  For a frame of reference think Print ‘01 in Chicago, just try not to remember that 9/11 fell right in the middle of the show :(   We finally had a good stable pigment based printer.  We had a few good RIPs emerging from the pack, but you still really needed 3rd party color management software to make the whole thing work.  Of course there was the nightmare of the day which was trying to find a suitable media for Graphic Arts proofing purposes.

The reality was if you understood all the steps involved (or hired a good color management consultant) you could make decent ink jet proofs that rivaled the standard analog and digital proofs of the day.

Now think about virtual proofing today.  While I believe there are at least two (and quite likely more) solid products capable of producing virtual proofs rivaling the ink jet proofs now carrying the standards flag; getting even those two systems to work in multiple locations can and does prove tricky at best.  This is no knock on the virtual proofing software vendors, but instead really an issue of hardware.

Putting together a solid ink jet proofing system requires an end-user to source a printer, media, a RIP, a computer to run the RIP, and probably a good color management consultant as well.  Putting together a solid virtual proofing system requires sourcing a display…let’s stop right there.  There is more to it, but the display is proving (at least my gut tells me this) to be a huge thorn in the side of virtual proofing working in multiple locations.

I am hearing some crazy numbers like less than 1 in 10 “qualified” displays can be used in a 2 or more location virtual proofing set-up.  If this is true (and I am starting to think it is), than it is no wonder virtual proofing is being used more and more for intermediate color (as I predicted in a previous post) and good old reliable ink jet proofs are still being produced as a final contract proof.

I still believe virtual proofing will continue to make gains over hard copy proofing.  I just think it may be a little slower than we thought until this display issues gets worked out.  Part of the problem is that measuring displays is not the easiest thing in the world to do….but that could be a whole post or even a complete white paper.

#69 IDEAlliance Proofing Summit in Review

Recently I attended the IDEAlliance Proofing Summit held in conjunction with the Publishing Business Conference and Expo at the Marriott Marquis in New York City. During the one day summit I managed to take three pages of notes focused on the meeting’s key topic of Virtual Proofing to the Numbers.

During the initial industry panel a question was raised about how to deal with virtual proofing systems from multiple vendors. Large publishers obviously deal with many printing companies and those companies make use of many of the different virtual proofing systems now available on the market. While it did not seem appropriate to make a comment during the meeting, I will remind my readers that ProofPass.com allows verification of ANY virtual proofing system with centralization of the results on a ProofPass.com internet server.

Bill Pope (of FTA) then spoke about the 2008 Virtual Proofing Systems Certification Program. Bill made a great point that sound color management is the key to successful virtual proofing. While ISO specs inks that most printers are now using, good color management is required to simulate those colorants on a monitor. Bill also made a great point about dealing with proofing disappointment up front. While I loved the comment, I think we all know that customers want what they expect x not necessarily what they see….

A fairly technical overview of the certification program was then provided. I found two items of particular interest during this portion; 1. A shift is being made to utilization of Delta E2000 for virtual proofing verification (already supported in ProofPass.com); 2. One of Bill’s key steps to verify that nothing has been “fudged” by the vendor is almost identical to the ProofPass.com verification procedure.

Some other comments I picked up throughout the day:

  • Pressroom monitors will need to be replaced approximately every 18 months.
  • Office/prepress monitors should last about three years
  • About 90% of the Pantone spot colors can be achieved with a high degree of accuracy on monitors costing about $5,000.
  • Grey balance uniformity corner to corner on a monitor is key
  • Color clipping on monitors might be overstated – it is localized to fully saturated colors and just results in a slightly duller rendition of the color.

All in all, it was a day well spent with the publishing and agency side of our business.

#67 Metamerism: Hard copy vs Monitor

The most visited post on JimRaffel.com in 2007 is #16 written October 2005 and addressing metamerism. Because of the popularity of this post I have decided to revisit the topic. I will start with some basic terminology and definitions. Then, I am going to present a real world example we are dealing with right now at ColorMetrix.

Definitions: First, metamerism requires a pair of objects. The two objects are often referred to as a metameric pair. In order to be considered metameric the pair must; match under at least one combination of illuminant and observer; not match under at least one combination of illuminant and observer; and have different spectral response curves.

Metramerism Tests: Post #16 shows an example of the GATF REHM indicator used for visual assessment of light sources. This is also an excellent of example of a visual test for metamerism. The two samples may also be measured by a spectrophotometer, and then an instrument test for metamerism can be performed. If the two samples exhibit a small Delta E under one illuminant observer combination, but have different spectral curves that cross at least three (3) times they are metameric.

Our ProofPass.com system was recently used to measure two samples. Below I have provided the L*C*h* values of a ‘Red’ swatch measured on a hard copy proof and then reproduced and measured on an LCD monitor.

  Hard copy Monitor
L* 40.56 43.02
C* 60.85 61.31
h* 28.44 27.9

The CMC(2:1) Delta E of the above two samples is 1.34 in a D50/2 degree environment.

Now, take a look at the spectral reflectance and emission curves of the two swatches. (Library Reading = Hard copy and Sample Reading = Monitor)

graph_spectralphp.png

Again the instrument test for metamerism states that if the spectral curves differ, and cross each other at least three times, then the objects are metameric. The curves look different and I count at least 10 crosses.

As long as the physical sample is viewed in a proper viewing booth, and the monitor continues to be calibrated and also viewed in proper conditions, the metamerism effects of hard copy vs. monitor proofing above should not be a problem. My concerns about this type of metamerism extend to placing a package on a retail shelf which is seldom a D50/2 degree environment.

65-1: SGIA Live Wednesday Observations

photo_102407_001.jpg

First, some general observations about the show.  While screen printing is still a very large part of the SGIA show, you do have to look a bit harder in between all the digital printing booths from the likes of Canon, Epson, HP and more to find screen printing products.  I am a new comer to the SGIA party, but had a general feeling that the show floor traffic was good.  Also, as with GraphExpo last month the quality of attendees seems high (the decision makers are here).

Use of color measurement technology is growing in the specialty graphic market.  I ran into Paul Foster of RIPware Limited displaying the ScreenReader which can be used for measuring the screen printing stencil.  For now it appears to be the only device in the world that can do so.  This device will make the linearization process for direct to screen machines much easier.  Also, when measuring a 50% patch on finished work it is nice to know that patch started as a 50% patch on the screen.

At the Nazdar Consulting Services booth I was introduced to their new CATZper (Color Approval and Tolerance by Perception) program.  The CATZper program allows for the physical output of visual reference and tolerance guides.  This could be a single spot color or an actual critical image.  The user is able to define the +/- color deviation allowed and that deviation can be different for each L*a*b* axis and direction.  Cool Stuff!

Both Epson and Canon have new printers on display.  At Epson the 11880 (Epson’s first 64 inch machine) is being shown as well as samples of their new back lit media product.  Using the 11880 a 64 inch wide backlit display can be printed and is ready to go.  At Canon the new 8 iPF8000S color printer announced and introduced at GraphExpo appears to be marking Canon’s return to the color proofing market.  Some folks I talked to at the show feel that technology changes to the printer make it a good potential choice for color proofing.

#58: I Still Love the Smell of Ink in the Morning

I have been so immersed in virtual proofing over the last several posts, that I had almost forgotten how much I still love the smell of ink in the morning. Last week I had the privilege of spending two days assisting a customer in the set-up of our software primarily for use as a pressroom monitoring tool.

The experience reminded me of #55: Just Measure It! The customer is a web offset shop and has the same problem that most of our digital printing customers have (Oh, I love the smell of toner in the morning too!). The problem is that their press product is finished product and has no trim. Color bars are not an option on production work, and changing the design to incorporate color swatches would also be impractical at this time.

The solution turned out to be the same solution we employee with our digital printing customers. A test form is put on press twice a day and the results of those measurements are used to verify conformance to density standards across the web. A second control strip can be scanned to gather other print metrics like TVI, Print Contrast, etc.

The results in a sister shop have been improved consistency from day to day and the ability to monitor changes in density and TVI from morning (cold press) to afternoon (warm press). In a perfect world I would love to see color bars on every job, but we thought outside the box and found them a solution that allowed us to measure. Once they started measuring quality and consistency improved. Profitability and productivity are never far behind quality and consistency improvements.

I raise the challenge again…today start measuring something in your color workflow that you are not measuring today. Within seven days those measurements will point the direction you need to go to improve the quality and consistency of that process.

#54: Some Thoughts and Comments about Soft Proofing

In #53 I listed a bunch of color resources I had found on the web. I was looking because we are putting the finishing touches on the first beta release of our ProofPass.com soft proofing verification module. For me this project has turned out to be about the journey not the destination. Of course the destination which is a viable commercial release of the aforementioned product that we hope to make lots of money on is not a bad place to end up.

The Journey, however, has been like going back to school for a guy so grounded in the color science of the physical ink on paper side of our industry. I have come to the conclusion that a monitor is just another “black box” that creates color from my perspective. Just like a hard copy proofing system, a conventional printing press, or even a digital printing press is. So, that means if it can be measured it can be controlled.

The key to successful soft proofing appears to lie in the color management behind the system(s). I recently had the opportunity to view and measure eight displays powered by the soft proofing technology of three vendors all in one place. All were powered by Macs, but the displays came from two manufacturers. In our quick and dirty technology demo three of these systems (all under the control of one organization) came in with a very tight peak Delta E of only about 3 between the systems.

Monitors using the other vendors soft proofing technologies fell further out (as the software was pre-beta at that time I am going to omit any further numbers). The verification module did, however, catch that one of the monitors had been profiled to the wrong white point (let’s just say I was pretty pleased with the new toy we built!).

Surround lighting and viewing conditions will make any quality soft proofing system work or not work. I have read papers on subject, I have tested it myself, and I have spoken to people who have done extensive testing of the systems. The less surround lighting (other than your 5000K light booth) the better. The surround and viewing conditions should be identical to the ultimate conditions when you make your monitor profile. One of the biggest factors I have seen to making a good or bad monitor profile is surround lighting.

It is clear to me that monitor proofing is here to stay in our industry, and is also highly viable when properly utilized. While I do not see monitor proofing replacing hard copy proofing altogether, I do see it replacing hard copy proofing in some applications very quickly. In other areas I see monitor proofing replacing many of the internal proofing iterations prior to the hard copy “contract proof” used press side. Much of this is going to depend upon how tight the deadlines are for being able to change copy, and the perceived quality level of the work being produced.

#51: Proper Press Fingerprinting takes Commitment

In this installment we will address the third question Dale raised in #47. Dale’s first two questions got answered in #48 and #49 which can be reviewed at JimRaffel.com.

Now, onto Dale’s third question:

3. In fingerprinting our presses, we’ve run up against the dreaded “Hurry up and do it, but don’t put too much work into it.” What are your recommendations for impressing upon the higher ups that doing color balancing and working out the calibrations takes time?

I would suggest you have your management read JimRaffel.com. The reality, however, is that the culture required for completing successful fingerprints starts at the top and does not get worked up from the bottom. I spent the better part of the first ten years of my career trying like heck to change the culture of a printing company (now out of business I might add) from the echelons of lower and middle management. While I hesitate to use the words “It can’t be done” (and not because my Mom the English teacher told me to never use contractions), I believe this is one place where this expression applies.

I have been very fortunate in my career. At 21 years of age before I had even graduated from RIT I was able to observe one of the pressruns used to set the early SWOP press standards. A lot of very smart people participated in this run and the scientific procedure was impressive. Then, not a year later I was the guy doing all the print quality measurements on a brand new Baker-Perkins G14 that cost about 9 million dollars back in 1986. While I was just one member of a very large team, the owner of the company made it quite clear that he was not making his first lease payment until we had a press that was printing correctly.

Over the next 3 years I had the same responsibility as 2 more new presses started up in that facility. In both cases, the purchase contract was very clear that we did not make lease payments until the press met our print quality standards. While the company in general had an difficult culture, in the case of all three of these press startups the message from the very top of the organization was “Do whatever it takes to get a solid press fingerprint.” The reason was simple, without a solid benchmark at startup how could we ever know what condition the press was in later?

Dale, it takes a great deal of time, money and a great team to perform a successful and meaningful press fingerprint. During the press startups above, the fingerprinting process could go on for a week or more. The press was fully crewed and lots of paper was run during this time. All the support staff had to be available from pre-press, plating, maintenance, materials handling, and more. I don’t think it’s an understatement to say that these fingerprint cost $100,000 or more.

Now, not all fingerprints need to cost that much. I took part in a very successful fingerprint within the last 30-days that probably cost no more than about $10,000 including our software and professional services time. It is, however, a matter of scale. The client for the 10K fingerprint was simply making the first investment in end-to-end color process control. All the key players in this organization participated in the meetings and remained on-site during the 2 (14 plus hour) days required to complete the fingerprint.

The results on the second day (and in follow-up calls the last three weeks) continue to be impressive. In the case above the press is not brand new but instead a fairly old and well worn pieces of iron which is now printing at an impressive level.

My conclusion is simple. If senior management of a PRINTING company is not willing to invest the time money and effort necessary to perform a proper PRESS fingerprint, one must really question the value of performing the fingerprint.

#37: Monitoring Digital Presses

At ColorMetrix we have some new and potential new customers who will be using our products (both ColorMetrix and ProofPass.com) to monitor and control digital presses like the HP Indigo, Xerox 8000, and NexPress. During our sales presentations most of these folks have expressed concern that the device is constantly self calibrating and correcting itself, so why would I need to do external process control?

My short answer: “Do you really want to let the fox watch the hen house?”

For the most part the internal controls on digital presses are built to keep the device in calibration. While these devices are different than conventional printing presses, they are not so different that we conventional printers do not understand them. There is a certain amount of variation that a conventional press self adjusts for like automatic register controls and the like. So, if we follow this augment to a logical conclusion that would mean process control would be useless on a conventional press as well. If you are reading this article I am fairly certain you do not believe that.

In general the act of process control requires the user to view the device (press in our case) as a black box. By measuring the resulting print the device produces, we are taking into account everything that happens in the device and the environment the device is in.

For example, several of these devices “self-calibrate” by imaging on a drum or a belt between actual substrate impressions. It seems to me we have removed a pretty important piece of the quality puzzle from that equation. What if our substrate is stored in a warehouse with no air conditioning and our press is in a climate controlled room? A week or so ago it was almost 100 degrees with very high humidity in the mid-west. If we bring that paper from the warehouse into the production room and do not provide 24 hours for the paper to acclimate, do you think we would get the same print result as we would with paper that had been acclimated?

If you said NO, please call me for a free trial version of ColorMetrix or ProofPass.com so you can measure it yourself.

In conclusion, all the variables that contribute to a printed piece like; faulty RIPs, toner changes, device wear and tear, paper changes, etc are viewed by a process control system like ColorMetrix as a black box. Process control systems like ColorMetrix measure the finished piece in order to accomplish two goals:

  1. Confirm that the finished print quality is within acceptable quality guidelines
  2. Provide detailed enough information to track back the problem portion of the process when #1 above is not achieved

Overall, the goal of the manufactures self-calibration procedure to stability of the imaging process itself. The goal of a system like ColorMetrix is overall print and color quality of the printed piece you put in the hands of your customer.

#21: The Reality of Remote Color Diagnostics

*** Golden Nugget #21: The Reality of Remote Color Diagnostics ***

While at the PIA/GATF Color Management Conference earlier this month I had a chance to visit with a customer who uses our new ProofPass.com proof certification and remote color diagnostics solution. Our customer is responsible for the operations of a large pre-press facility and for this article we will call him John Smith.

Recently John was out of the office at a user’s group conference for another piece of critical equipment or software in his facility. John got a frantic call from the office that recently produced proofs could not be matched on press. John’s first concern was to check on the current state of his inkjet proofing system. He asked that a new proof be made and scanned into the ProofPass.com database.

Because the ProofPass.com database is internet based, John was able to login to the ProofPass.com web-site with his account information and see the color of the swatches just measured along with almost every print metric a person could wish for. The visual swatches in ProofPass.com proved to be the key to solving this problem. Before John even started looking at the delta E numbers he could see that the side-by-side color comparison of the reference proof (gold standard) and the recently produced proof did not match.

Obviously doing this comparison on a color calibrated monitor in proper viewing conditions aids in the correctness of the colors being viewed. Remember, however, that ProofPass.com is not intended to display “contract color” but instead to provide the user a visual reference of the relative color difference between two color swatches.

The shift observed was quite large, and in the overall direction of a much “warmer” proof. While almost every swatch passed the delta E test in place (I believe John has since tightened his delta E tolerances) it was this overall shift vs a single patch shifting that was causing the problem. John runs a simple device next to the inkjet proofer that plots both temperature and humidity over time. In the period of time that the color problem had occurred humidity had dropped from about 60% to 20%.

In conclusion, remote color is clearly the most exciting technology to hit our industry in many years. While we have all seen the potential of remote “soft proofing” I believe the broader category of remote color is going to provide much of the excitement and growth in our industry over the next five years. It promises to be a heck of a ride, so climb aboard and let’s see where it takes us.