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Author Topic: Neutral Profile ?  (Read 2953 times)

cliffspicer.com

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Neutral Profile ?
« on: October 05, 2011, 01:44:15 pm »

Hello,

 I understand the basics of colour management as it pertains to photographers but I want to deepen my understanding. What I really want to know is how to evaluate my profiles to see if they are the best they can be. I currently own an i1 and I am using i1match for my RGB profiling (Epson driver) but I have i1Profiler on order. I created a profile to see if I can improve on the canned one supplied by Epson. I checked my profile against the epson profile on a 2D and 3D graph in ColorThink and they are similar in shape. What I am struggling with is that the prints are not as neutral as I had hoped I could get them and this applies for both the Epson Profile as well as mine. I am viewing the prints in a light box that when I checked using i1share had a white point of D50, CRI of 90 and a lux of about 1000. What I wanted to do was get under the hood as they say and see what was going on so I did the evaluation test of how neutral my profile was and below is the graph. I am not exactly sure what I am seeing here and any assistance would be appreciated. I also wondered if I printed out a grey ramp using the profile and measured it using my i1 would I expect the Lab values to show me a neutral reading along all points on the ramp and what would be an acceptable tolerance between a and b? Many thanks for your help. It is really appreciated.

All the best,

Cliff
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digitaldog

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Re: Neutral Profile ?
« Reply #1 on: October 05, 2011, 03:48:44 pm »

Profiles don’t know squat about images. They just understand solid color patches. There are evaluations one can make to provide fixed numbers (the deltaE to the profile where you examine the measured and expected colors and report). But first things first. Make prints of images from these profiles! View them properly. Use if possible, good test images that exploit the profile (stuff with differing colors, gradients etc). Something like Bill Atkinsion’s test images, Roman 16, some synthetics etc.
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cliffspicer.com

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Re: Neutral Profile ?
« Reply #2 on: October 05, 2011, 04:04:14 pm »

I have printed out sample image targets (yours from your site) and I am getting a shift to the greens when I look into the grey ramp on the top of the test image.

Are you suggesting that I print a target, read the values and compare them in PMP for the overall Delta E? If so will this tell me an overall Delta E and should I want a reading of 3 or less or do I have the process wrong. If my Delta E is higher do I assume one of the following:

* the profile target was originally not read correctly and should be measured again?
* i1Match is not the right tool to create good RGB profiles and I need a more complex package such as i1Profiler?
* The printer is just not capable of getting a decent neutral colour balance across the grey ramp no matter what is done?

Thank you for your help and I am assuming from your not making any comments about the graph that was made in ColorThink that you think it is a waste of time to start my search there. If that is the case is there a place for this module in colorthink?

Many thanks again,

Cliff

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digitaldog

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Re: Neutral Profile ?
« Reply #3 on: October 05, 2011, 04:07:16 pm »

I have printed out sample image targets (yours from your site) and I am getting a shift to the greens when I look into the grey ramp on the top of the test image.

Are you suggesting that I print a target, read the values and compare them in PMP for the overall Delta E? If so will this tell me an overall Delta E and should I want a reading of 3 or less or do I have the process wrong. If my Delta E is higher do I assume one of the following:

* the profile target was originally not read correctly and should be measured again?
* i1Match is not the right tool to create good RGB profiles and I need a more complex package such as i1Profiler?
* The printer is just not capable of getting a decent neutral colour balance across the grey ramp no matter what is done?

You could read stuff but you see green so what’s the point?

I don’t know if its a bad read, probably not. You’d see posterization in most cases. It could be the size of the target used and i1Match. When you get PROFILER, build a new profile from a custom target, then if you still need to tweak the gray balance, there’s this:

http://www.i1upgrades.com/2011/08/how-to-use-the-tc-2502-gray-optimization-chart/
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cliffspicer.com

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Re: Neutral Profile ?
« Reply #4 on: October 06, 2011, 12:17:37 pm »

Thank you so much Andrew. I really appreciate your time.
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cats_five

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Re: Neutral Profile ?
« Reply #5 on: October 06, 2011, 12:37:42 pm »

...
I am getting a shift to the greens when I look into the grey ramp on the top of the [printed] test image
...

Getting a neutral grey print can be very hard, depending on the printer, the ink and the paper.  You can also get grey prints that have different casts in different lights, AKA metamerism.  In the examples I've seen. green and magenta seem to be the commonest casts.

If your printer has black and coloured ink then it may be trying to mix pale greys from the colours and that frequently fails to convince.  If your printer has one or more grey inks as well as black then you may need something specific in the print driver to get it to use those rather than the coloured inks.  You haven't said what printer it is...
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cliffspicer.com

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Re: Neutral Profile ?
« Reply #6 on: October 06, 2011, 01:15:22 pm »

Thanks for the reply. I am profiling an Epson 1400 and I realize this mixing of the colours to make grey is a big issue but I am not sure how to tell if I have the best possible profile. I get smooth ramps both in black and white and all the colours on the test chart. My skin tones are not bad but for printing black and white I am getting a shift to the greens. If I do have the best profile possible, then maybe running the print through my profiled scanner and measuring a ramp to create an adjustment curve to correct the colours may be something to think about. A bit of a hack I know.
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Tim Lookingbill

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Re: Neutral Profile ?
« Reply #7 on: October 06, 2011, 06:05:38 pm »

Do you see green viewing the print under direct sunlight? How about under any other artificial light than the one you're currently using?

I'ld check that first, before going down a complicated road of reprofiling and tweaking for neutral gray.

I'm amazed I can get perfectly neutral grayramp printing to a $70 Epson NX400 "3 in 1" printer on Epson Ultra Premium Glossy paper using non-traditional non-color managed settings through the printer driver. However, it only works on that paper with those specific printer driver settings. The sRGB space grayramp looks neutral under 5000K GE Sunshine fluorescent tube and under direct sunlight.

Knowing your paper you're printing on would be helpful information as well.
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tony22

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Re: Neutral Profile ?
« Reply #8 on: October 06, 2011, 07:04:10 pm »

When you get PROFILER, build a new profile from a custom target,

Andrew, is the implication here that a custom color target is the better way to go with i1Publish than using one of the "stock" targets in the program? If yes, is there a recommendation on what this custom target should look like?
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cliffspicer.com

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Re: Neutral Profile ?
« Reply #9 on: October 07, 2011, 11:02:36 am »

I am using a brand of paper called InkPress with the luster finish. This paper is heavy on the OB and I specifically see see more of a tint under artificial light or light that has a very erratic spectral response. I am guessing this is the metamerism of the ink paper combination since I don't see the same intensity of the colour cast (but it is still there) under daylight. However, I am showing these prints under artificial light and would like to minimize this shift in colour. Do you think a profile that takes into account the ambient light would solve my problem if metamerism is the issue? Would switching papers that are more neutral to begin with be a good idea or are the OB taken into account when the profile is created and therefore this factor is eliminated.

Many thanks to all who are joining in on the conversation,

Cliff
 
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digitaldog

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Re: Neutral Profile ?
« Reply #10 on: October 07, 2011, 12:39:44 pm »

Andrew, is the implication here that a custom color target is the better way to go with i1Publish than using one of the "stock" targets in the program? If yes, is there a recommendation on what this custom target should look like?

That’s been my experience.
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tony22

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Re: Neutral Profile ?
« Reply #11 on: October 07, 2011, 07:16:30 pm »

That’s been my experience.

Is there a link where you've talked about this before? If not, could you provide a bit of guidance as to an acceptable starting point custom target? Thanks.
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Tim Lookingbill

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Re: Neutral Profile ?
« Reply #12 on: October 07, 2011, 08:51:50 pm »

Quote
I am using a brand of paper called InkPress with the luster finish. This paper is heavy on the OB and I specifically see see more of a tint under artificial light or light that has a very erratic spectral response. I am guessing this is the metamerism of the ink paper combination since I don't see the same intensity of the colour cast (but it is still there) under daylight. However, I am showing these prints under artificial light and would like to minimize this shift in colour. Do you think a profile that takes into account the ambient light would solve my problem if metamerism is the issue? Would switching papers that are more neutral to begin with be a good idea or are the OB taken into account when the profile is created and therefore this factor is eliminated.

Many thanks to all who are joining in on the conversation,

Cliff

Print the grayramp on another paper like Epson's using its appropriate profile and print settings and view under the same artificial light and daylight to check for green there. This will definitely point to a print driver problem or a print head cleaning issue which you might give a try as well.

As for having the profiling software correct for OB's you'll have to refer to Andrew's expertise on this. I've never made a custom printer profile or even had concerns with OB and their affect on mixing with the ink and paper color cast. I've always stuck with Epson printer paper, inks and canned profiles on a Photo EX, 1270 and now the NX400. I haven't printed in quite some time as well, but I do know what various lights do to the appearance of inkjet paper color casts but never changing color of inks.

With prints made with Epson inks and paper the only color shift under various lights is the color cast provided by the light itself with the 5000K GE Sunshine giving a slight reddish yellow tint to B&W, 50 watt Solux 4700K giving spot on neutrals, 100 watt Ottlight HD CFL slight bluegreen cast and the 100 watt Alzo Digital CFL a slightly blue cast.
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octagon

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Re: Neutral Profile ?
« Reply #13 on: October 07, 2011, 11:15:39 pm »

Is there a link where you've talked about this before? If not, could you provide a bit of guidance as to an acceptable starting point custom target? Thanks.

He's just talking about using the i1Profiler software in advanced mode and generating a larger test chart, at least that's what I think he means. I've seen Andrew say previously that I1Profiler generates great profiles from its own test charts (see the review on this site for instance).

Use the patch generator and watch the gray patch selections it uses. There are a number of patch sizes where the chart generator uses a lot of gray patches, and then selecting one more patch suddenly changes the whole configuration, and there are very few gray patches. Choose a patch number that uses a lot of gray, for instance 1215 patches.
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cats_five

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Re: Neutral Profile ?
« Reply #14 on: October 08, 2011, 02:44:24 am »

I am using a brand of paper called InkPress with the luster finish
...

I see there seems to be a downloadable for your printer on the Inkpress website - have you tried that?
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tony22

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Re: Neutral Profile ?
« Reply #15 on: October 08, 2011, 08:27:13 am »

He's just talking about using the i1Profiler software in advanced mode and generating a larger test chart, at least that's what I think he means. I've seen Andrew say previously that I1Profiler generates great profiles from its own test charts (see the review on this site for instance).

Right. I saw how that can be done in 1Profiler so I assumed the same. I was wondering if Andrew had a patch number that he's discovered will produce better results than others. I did look at the review thread a while ago. I guess I should take another read through it. Thanks.
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