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Author Topic: [Color Study] Create CMYK Profile  (Read 542 times)

aaronchan

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[Color Study] Create CMYK Profile
« on: July 05, 2018, 01:11:12 AM »

Hi all,

I have been using different softwares and tools to create my RGB printer profile for my printing business for the past 10 years.
So far, I'm pretty comfortable about it.

Recently, I'm starting to study CMYK profile for my own interest.
I used to study color management and fine art printing from Tom P. Ashe when I was in school, took a year independent study with him.
But during that time period, we didn't really get into the CMYK world with RIP, we more focused on the outcome and with the RGB driver.

Here I have attached my reference chart, measurement and icc.
The shape of the ICC does not look right at all, at least to me.
Can anyone could point me a direction where did I do wrong to create such an ugly ICC?

I am using Ergosoft RIP with Epson P6080
OEM ink and some affordable semi-glossy RC paper
i1Profiler
Ink Limit: 180
Use intelligent black: On
Black start: 0
Maximum black: 100
Black curve: med
Black width: 60

Reference File
Measurement
ICC Profile

Thanks
Aaron

arobinson7547

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Re: [Color Study] Create CMYK Profile
« Reply #1 on: July 05, 2018, 08:29:46 AM »

As CMYK Profiles go, that is not a 'bad' Profile. OK it don't look like the perfect pretty picture. But that's why you profile the device. One challenge of CMYK profiling for Inkjet is getting the right balance of C to M to Y. For me M benefits from being highest, C lower and Y, the lowest.

On the Cannon, my personal challenge is getting past the fact the black doesn't get blacker when other inks are added. It makes for a shadow that is Black only, at the extreme end and can actually raise up when the other inks are added to it.


Trying to get a 'close to neutral'  (a & b being as close as possible) is beneficial. When doing this the L value is going to go WAY up, but don't worry, Black is there to get that Low L* back.

In your Profile, you could try lowering Magenta a little.

For me, it's all about the relationship of the CMY inks and getting an Ink Limit that serves you best; Low L* but not so low that you loose shadow detail.


With CMYK, you get a lot more control, but it's a lot more work. Dialing in the Channel Limits, Balancing CMK, (you are even afforded the option of Gray Balancing CMY from the Highlight to Shadow, making your Printer perfectly neutral, before adding black. This should be BW Printing Heaven, i.e., G7.

To work those shadows out though, you have to start with limiting and balancing the individual channels. As an example, look at your Red Green and Blue, it they are too dark and heavy, bring the corresponding channels down a bit.

Just some thought.




Theory and Practice don't always go hand-in-hand, and this is one of those times.
l
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aaronchan

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Re: [Color Study] Create CMYK Profile
« Reply #2 on: July 06, 2018, 10:47:47 AM »

Thanks for your reply.
Seems like not a lot of people are working with CMYK profile here.
One thing about using a RIP is seems like no matter what I do, the print won't comes out as smooth as the printer driver.
I can easily see the screening dots on the print. I'm wondering that's my profile problem or the RIP problem...

Thanks
Aaron

As CMYK Profiles go, that is not a 'bad' Profile. OK it don't look like the perfect pretty picture. But that's why you profile the device. One challenge of CMYK profiling for Inkjet is getting the right balance of C to M to Y. For me M benefits from being highest, C lower and Y, the lowest.

On the Cannon, my personal challenge is getting past the fact the black doesn't get blacker when other inks are added. It makes for a shadow that is Black only, at the extreme end and can actually raise up when the other inks are added to it.


Trying to get a 'close to neutral'  (a & b being as close as possible) is beneficial. When doing this the L value is going to go WAY up, but don't worry, Black is there to get that Low L* back.

In your Profile, you could try lowering Magenta a little.

For me, it's all about the relationship of the CMY inks and getting an Ink Limit that serves you best; Low L* but not so low that you loose shadow detail.


With CMYK, you get a lot more control, but it's a lot more work. Dialing in the Channel Limits, Balancing CMK, (you are even afforded the option of Gray Balancing CMY from the Highlight to Shadow, making your Printer perfectly neutral, before adding black. This should be BW Printing Heaven, i.e., G7.

To work those shadows out though, you have to start with limiting and balancing the individual channels. As an example, look at your Red Green and Blue, it they are too dark and heavy, bring the corresponding channels down a bit.

Just some thought.




Theory and Practice don't always go hand-in-hand, and this is one of those times.
l

GWGill

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Re: [Color Study] Create CMYK Profile
« Reply #3 on: July 06, 2018, 09:04:43 PM »

One thing about using a RIP is seems like no matter what I do, the print won't comes out as smooth as the printer driver.
I can easily see the screening dots on the print. I'm wondering that's my profile problem or the RIP problem...
Yes. There's no guarantee that the RIP is driving the printer as well or better than the manufacturers screening/dot choice. It gets complicated when there are multiple dot sizes, ink densities (light/medium etc. ink), printing densities and separation rules, and getting an optimal result can take a lot of work and experimentation.

Generally the black rule can have a big effect on screening visibility. High black in the shadows means it can be quite visible. Low black/high CMY minimizises screening visibility. Trade-off is poorer neutral robustness.
 
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