Digital Printer and G7?

[herbie000]

We have a Canon 6000 and the only way to "control" color is by using ICC profiles. I printed the IT8 7.4 then made a profile from the IDEAlliance gracol numbers I downloaded. When I apply the icc it tints the stock gray. Is anyone out there controlling the digital printer with icc profiles or making it G7 I would appreciate any tips you could give me.

[rich apollo]

Are you using the Absolute Colorimetric rendering intent?

[herbie000]

I have tried all the rendering intents and get the same results. We calibrate the machine to the suggested Hammermill paper, I wonder do I need to re-calibrate to the paper I am running now is just 20lb bond?

[rich apollo]

The only rendering intent that should affect the paper color is Absolute Colorimetric. The other three should leave the white alone.

[Mike Strickler]

This is a little unclear. You want to simulate GRACoL on your printer? Yes, you do need ICC profiles to do it well, even if you were able to apply G7 curves in your RIP--overprints especially require ICC color management to match them. Just linearize as best you can, setting ink limits a little higher than you need to print the GRACoL solids and TIL no higher than the paper will hold without bleeding, etc. Turn off CM and print the IT8.7/4 or other CMYK profiling chart, make the profile (use a heavy GCR and early black start if you have a "light black" ink), integrate it back into your workflow, and turn CM back on. Download the GRACoL2006 profile and use it as your reference/source, with abs. col. as the rendering intent. Print the profiling chart again, this time through your workflow with CM turned on. Measure the chart and compare with reference GRACoL Lab values to see where things stand.

[Mike Strickler]

Who suggested the Hammermill paper? if you're trying to simulate GRACoL you need a coated paper that can hold at least as much color as a #1 coated press substrate. Maybe I've completely misunderstood what you're trying to do...

[herbie000]

Hammermill is what Canon recommends for the calibration. We are not going to be running Hammermill we will most likely be running 20lb bond the most and a few other coated sheets. What I need to be able to do is match the G7 standard for Gracol1 and SWOP3. I have downloaded the IDEAlliance target numbers then ran the ECI chart on the canon and made an ICC profile from that. When I use the profile it turns the background gray. Now I am a bit suspicious of the data I downloaded because when I use a ICC profile I built from a Web press run I don't get the gray in the background but it should be simulating a groundwood stock and there is no simulation on the paper. I have tried all the rendering intents again it did not make any difference. Do the rendering intents even work? I am starting to think they don’t.

The reason we calibrated to the Hammermill is because it’s a whiter paper and a larger color gamut. So we can get the “best/most” color from the machine and dumb it down from there to match the Web presses.

[LoganBlade]

Scold me if I am wrong BUT if you want your profile to be good you should be using the stock you are running. Profile will do its best on th estock your running. You would then build a profile for each stock so it will all look close in appearance.

[herbie000]

You are correct I did it that way to start with and it did not work. So I tried it the way Canon told me and it's still not working.....any one have any other ideas?

[Werby]

Please clarify exactly what you are doing. Are you using a RIP or are you using these profiles when printing out of a program (like Photoshop) directly to the printer? If you are printing directly (no RIP) which program are you printing out of and exactly what settings are you using? Where are you selecting your rendering intent? What software are you using to make your profiles, and what settings are you using there?

You said you "ran the ECI chart on the canon and made an ICC profile from that". As Michael Collins said, this process MUST happen on the paper you are going to finally print to. A profile describes a very particular print condition, so if you want to use it accurately, you have to EXACTLY replicate that print condition later. So you can't change paper or resolution or any other setting which might effect the color. If you create a profile of your output device in one condition, then change the condition, then that profile is no longer valid.

Assuming that the profile is correct, you quite possibly will get some paper tint, as your hammermill is almost definitely brighter than GRACoL and SWOP. If you truly want to emulate those print conditions, then you WANT a paper tint. For SWOP it is going to make your paper gray. Depending on your RIP or your print settings, there may be a way to turn that off, but you need to say what they are in order to figure that out.