#49: Dialing in an Image setter or Plate setter

#47 generated a comment from Dale, which contained three good questions I intend to answer over the next several weeks. Also, later this week I intend to blog from the floor of the PMA show where my activities at JimRaffel.com have qualified me for a Press pass to the show. While my main purpose for attending the show is to conduct several meetings with strategic business partners who will be there I also plan to take a good look at how wide format ink jet printing is progressing in the photo market.

Now, onto Dale’s first question:

I have a question. I know this might sound simple, but: 1. For a beginner who is given an Imagesetter, several jobs and told “Go output films and get it right” what should be the first step?

My first thought was wow, Dale this is not a simple question. The answer to this question is an explanation of end-to-end color process control. Having just spent two very long days implementing end-to-end color process control at a client facility the steps are fresh in my memory. Suffice it to say that the events of two 12-14 hour days can be summarized in this article, but space will not allow for the level of detail needed to call this a step by step procedure.

First, I am going to assume that the image setter in question is actually a plate setter (I know from Dale’s question it is not but read on). The process is very similar, and to begin discussing all the concerns I would have with a film based image setter (Dmax, Dmin, chemistry replenishment, exposure frame for getting film to plate, etc.) would be an article or two in itself. I will say that if you are still outputting film give some serious thought to moving to Computer to Plate (CTP).

So here is my take on implanting end-to-end color process control:

1. Follow all of the manufacturer’s procedures to calibrate and linearize the plate setter. We will need a set of linear plates very soon. Output a plate with a full tone ramp and measure with the best plate reading device you have to confirm plate linearity.
2. Create a press test form containing the elements that are critical for your application. I would go into more detail here, but I have never used the same press test form twice. Most printers print for niche markets that demand reproduction of different colors and images that need to be on the form in addition to grey balance bars, tone ramps, slur and double targets, etc.
3. Without applying any color management output the test form to the plate setter.
4. We will now run these plates on press with a typical middle of the road paper you run day in and day out. Also, while we do not want brand new blankets on the press, we also do not want a set that is about to be changed. The whole point here is to run to the “middle of the road.” (Again, this step alone could be an entire article or two.)
5. Run single colors over a wide density range, from starved to piling. Using the Print Contrast method, determine the optimum density for each ink color.
6. Next, run the test form as 4/color at the densities determined in #5. This step is to have a visual comparison of before and after as well as to collect the Tone Value Increase (TVI) values of the entire tonal range and other print metrics like Trap.
7. Note: from here on I assume a color managed workflow solution. Many organizations simply look at the 4/color tone ramps and create cut-back curves for the plate setter to achieve desired TVI. While this method works pretty well it is somewhat difficult to create proofs for.
8. Run a color management target on press which is supported by your color management solution. Run to the densities determined in #5. Also, confirm that the pull sheets have TVI close to those determined in #6.
9. Use 6 or more of the sheets collected in #7 to create an averaged press profile.
10. Apply the press profile to the images in the test form created in #2, and output new plates. It is very important that you do not apply color management to the entire test form. We need the color bars to remain linear.
11. Mount the plates and run to the densities from step #5. In every plant that I have applied the above procedure, the results have been pretty amazing.

The important thing to remember is this is just a starting point. Process control steps must be put in place to ensure; that the plate setter does not drift; to confirm that the press is still printing to the correct densities and TVI; that materials like ink, plates and fountain solutions have not changed.

Also, in order to obtain end-to-end color process control, additional steps like monitor calibration and proof certification will need to be instituted. There is a book titled Quality is Free, and I disagree. Quality is an investment with a Return on Investment. The largest part of that investment is time. If you are working in an organization that is not willing to commit the time necessary to follow a procedure like the one above and you want to be part of a quality printing operation…here’s the link for Monster.com.