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Author Topic: More tones in the grayscale image the less neutral it looks... why?  (Read 455 times)

DavidPalermo

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When I print a high contrast BW photo the print looks very nice... very neutral, yet when I print an image with more gray tones it has a blue-ish cast. I am printing on Hahnemuhle paper but I have noticed it on other paper brands. Specifically I am using Photo Rag and Bamboo. If I tint the image in Epson's ABW print drive to 5,20 it looks better but I'd rather not have to tint it.

Do any of you know why this might be happening? Do any of you experience this?

I'm using an Epson P800 and a Epson 3880.  I am using Epson's ABW driver. And the files contain no color so I am certain it's the files themselves.

Thank you!
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Mark D Segal

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Re: More tones in the grayscale image the less neutral it looks... why?
« Reply #1 on: February 10, 2019, 08:55:22 PM »

Have you tried printing the ones with the grayscale the regular way with the ICC profile for the paper you are using, to compare? What Epson Media Type have you selected in the Epson driver for printing with those non-Epson papers? Whether you use ABW or ICC, you do need to select an appropriate Media Type otherwise you can expect uncharacteristic results.

When you say the files contain no colour, what do you mean by that? Were they converted to B&W from colour, or were they original B&W photographs? What do you mean by "it's the files themselves"? This doesn't resonate with anything I can relate to in my experience with colour-managing prints. Are you trying to say they were converted from colour and in that process may have a residual blue bias in the file numbers?
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Mark D Segal (formerly MarkDS)
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DavidPalermo

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Re: More tones in the grayscale image the less neutral it looks... why?
« Reply #2 on: February 10, 2019, 09:41:49 PM »

Hi Mark,

The files were converted to grayscale in LightRoom... exported to Photoshop for retouching etc... back into LightRoom for printing...

Media Type is Velvet Fine Art which is what the recommended media type is for these papers.  I am not using the paper profile but rather Epson's Advanced BW driver which is also recommended for printing BW.

The files contain no color - I said that because I didn't want someone to respond by saying "maybe they are not true grayscale files etc. etc...  I made sure by sliding the saturation slider in LightRoom all the way up to make sure there was no color.

I misspoke on "it's the files themselves".  That should read "it is not the files".

If an image is high contrast with fewer mid-tones and mostly black and white the prints look great! Then I print an image containing more shades of gray it looks blue-ish...  Viewing conditions are exactly the same for each print.

I have noticed this before on my 3880 but have not posted about it.

« Last Edit: February 10, 2019, 09:54:30 PM by DavidPalermo »
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Mark D Segal

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Re: More tones in the grayscale image the less neutral it looks... why?
« Reply #3 on: February 10, 2019, 09:56:33 PM »

I've tested ABW on the P800 and on the 3800 (bit not the 3880); the grays were definitely not bluish, and this same error is unlikely to happen to two printers of different models. So I strongly doubt this is a generic problem and I do think there is something causing it upstream of the print process that you may not be doing correctly. Have you tried making the same prints using the standard ICC approach with Lightroom managing colour? I think you should do that, because if these results come out better, it would suggest some settings issue between the ABW driver and the B&W conversion mode in LR (there are several approaches to doing it - see Martin Evening's LR book, pages 350-359).
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Mark D Segal (formerly MarkDS)
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MHMG

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Re: More tones in the grayscale image the less neutral it looks... why?
« Reply #4 on: February 10, 2019, 10:56:57 PM »


...If an image is high contrast with fewer mid-tones and mostly black and white the prints look great! Then I print an image containing more shades of gray it looks blue-ish...  Viewing conditions are exactly the same for each print.


I recently had the same problem on my Epson SC P600. Turned out to be a bad LLK cartridge. It would pass the nozzle check, but the gray scale neutrality would veer decidedly towards blue after a perfect nozzle check. Recheck nozzles and a failing nozzle check would happen, clean and get proper nozzle check output, reprint, yet another bluish print would ensure...replace LLK cartridge, all was well.

I can't explain that passing/failing nozzle check behavior on the defective LLK cartridge. All I know is that replacing that cartridge solved the bluish gray shift which was quite pronounced when the defective LLK cartridge was installed.

Perhaps this is what's happening in your situation. You might try replacing some of the photo gray cartridges, especially the LLK. If it solves your issue, then you have identified the problem. If not you can always reinstall the older cartridges, use them up, then switch to the newer cartridges once again. Just keep the opened fresh cartridges sealed in a plastic bag, They should be OK when you reintroduce them to your printer.

cheers,
Mark
http://www.aardenburg-imaging.com
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Mark D Segal

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Re: More tones in the grayscale image the less neutral it looks... why?
« Reply #5 on: February 11, 2019, 08:31:10 AM »

That is really interesting - and troublesome - experience Mark. I say troublesome because it raises a generic issue I had been advised should not arise. Like everyone else, I've had my problems and issues with colours not emerging correctly in prints and way back in the time when I consulted with Epson ProGraphics about whether the problem could be clogged nozzles of the relevant channels they assured me that as long as the nozzle check has no gaps the ink is flowing properly and that was not the cause of my problem. So since then I took it for given that nozzle checks are a reliable indicator of ink flow - but your experience now suggests maybe not. If that's the case it's a generic concern.

What got me thinking that Mr. Palermo's problem is upstream of the printer is his report that it has happening with two printers of considerably different vintage. So perhaps some error somewhere common to both workflows but upstream of the printer in both. I do hope he accepts my suggestion to make the prints using application managed colour and standard ICC profiles. The result of that experiment could help diagnose where the problem sits.
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Mark D Segal (formerly MarkDS)
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MHMG

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Re: More tones in the grayscale image the less neutral it looks... why?
« Reply #6 on: February 11, 2019, 09:38:44 AM »

That is really interesting - and troublesome - experience Mark. I say troublesome because it raises a generic issue I had been advised should not arise. Like everyone else, I've had my problems and issues with colours not emerging correctly in prints and way back in the time when I consulted with Epson ProGraphics about whether the problem could be clogged nozzles of the relevant channels they assured me that as long as the nozzle check has no gaps the ink is flowing properly and that was not the cause of my problem. So since then I took it for given that nozzle checks are a reliable indicator of ink flow - but your experience now suggests maybe not. If that's the case it's a generic concern.


When my nozzle check failed, it revealed that the LLK channel had totally dropped. A single cleaning cycle could get the channel back into full operation, but the problem soon returned as evidenced by another nozzle check after I noticed the grayscale going bluish again. Because the channel was dropping out so completely and was so unreliable, I figured this wasn't really a clog in the conventional sense. It was insufficient ink flow going to the print head for that channel. The nozzle check was still acting as an effective QC check on the print head even if the cleaning cycle was producing only a short-lived fix.  For that reason I decided to swap out the LLK cartridge with a new one, and the printer has been running fine since the swap. The P600 has a pressurized ink feed system. My guess is the bad cartridge was reducing the normal pressure in the system causing ink starvation at the print head.

As for why the gray scale can drift bluish, a probable reason is that the UltraChrome photo grays are more of a warm gray (slight brownish tint) and thus not totally neutral. Cyan and perhaps some  magenta are being added in smaller amounts to counteract the warmth and thus achieve a more neutral gray on many media. If the LLK or LK channels are not delivering full output, then the equivalent neutral density balance between those photo grays and the cyan/magenta blending would be off, thus the printed gray values would be shifting towards cyan/blue.

I agree with Mark S. that the odds of this cartridge issue affecting two different Epson printer models at the same time seems pretty darn low, so the OP's bluish gray issues may be stemming from another systematic error, but I thought my recent bluish-gray neutral problem and the "fix" was worth sharing.

cheers,
Mark
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Mark D Segal

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Re: More tones in the grayscale image the less neutral it looks... why?
« Reply #7 on: February 11, 2019, 10:07:03 AM »

Yes, worth sharing, and interesting insight on the hue of the Ultrachrome grays.
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Mark D Segal (formerly MarkDS)
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Paul Roark

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Re: More tones in the grayscale image the less neutral it looks... why?
« Reply #8 on: February 11, 2019, 10:40:19 AM »

If one prints only black and white, the solution I use is to have most of the channels/carts be 100% carbon pigment -- at different dilutions.  Only one position is a color "toner" to give me control of the print tone along a straight line from carbon warm to "neutral" (which I happen to think looks better with a slightly positive Lab A).  I at one time used B&W inksets with full color control, but I found most people can't control the tone unless it's pretty much in a straight line -- i.e., limited variables.

See, for example, http://www.paulroark.com/BW-Info/7800-Glossy-Carbon-Variable-Tone-2016.pdf .

Note that I use 2 MK positions to get a good dmax on Arches watercolor paper.  I don't recommend most use this.  Without the need for 2 MKs, the inkset approach would be like the 3800 setup described here:  http://www.paulroark.com/BW-Info/3880-Carbon-Variable-Tone-2015.pdf , but I'd substitute PK as the starter for MK now, as the newest MK does not seem to have any advantage to PK in terms of being more neutral.  On the flip side, nothing is less expensive than a matte paper only B&W inkset using my generic dilution base (c6b).  See http://www.paulroark.com/BW-Info/Ink-Mixing.pdf

The blue-cyan mix in the toner is where the Lab A can be adjusted if wanted.

In my view the Epson LLK is greenish.  I doubt it is 100% carbon.  I'd guess it's a combination of carbon and cyan pigments.  My experience is that different pigment types tend to separate somewhat.  As such, it might be a good idea for people seeing a hue in their Epson "neutral" inks to agitate them (as well as all the carts) periodically.  Pigments settle slowly.

BTW, if you're in the Santa Barbara, CA area from mid-Feb to mid-April, stop by the Elverhoj Museum (http://www.elverhoj.org/index.html) to see a show of my B&W prints. (I have a map linked to my home page, URL below.)

Paul
www.PaulRoark.com
http://www.paulroark.com/BW-Info/
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howardm

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Re: More tones in the grayscale image the less neutral it looks... why?
« Reply #9 on: February 12, 2019, 08:18:02 AM »

Paul,  how slow is slow with respect to pigment settling sufficient to cause 'change' in the output?

I personally do not like endlessly yanking the carts out to shake them.  Maybe I'll get/make some sort
of 'shake table' for my 3880 :D

Rand47

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Re: More tones in the grayscale image the less neutral it looks... why?
« Reply #10 on: February 12, 2019, 10:33:01 AM »

When I print a high contrast BW photo the print looks very nice... very neutral, yet when I print an image with more gray tones it has a blue-ish cast. I am printing on Hahnemuhle paper but I have noticed it on other paper brands. Specifically I am using Photo Rag and Bamboo. If I tint the image in Epson's ABW print drive to 5,20 it looks better but I'd rather not have to tint it.

Do any of you know why this might be happening? Do any of you experience this?

I'm using an Epson P800 and a Epson 3880.  I am using Epson's ABW driver. And the files contain no color so I am certain it's the files themselves.

Thank you!

Have you checked the neutrality of the file(s) using the L a b numbers readout in LR?  Be interesting to check / affirm that the file really is neutral.

Rand
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Rand Scott Adams
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