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Author Topic: Lumejet Process Overview  (Read 5555 times)

photodan19

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Re: Lumejet Process Overview
« Reply #20 on: February 26, 2018, 06:45:03 PM »

I am posting this at the risk of revealing myself to be a member of an apparently tiny minority of Lula members who do not own nor plan to own an inkjet printer.

I certainly would love to have the superior color gamut of inkjet pigment printing, the print longevity, the apparent detail; but also the smoothness and seemingly infinite detail of the N-surface paper from large format film, and for it not to cost a fortune, and for the prints not to be damaged by a slip of the finger.

I don't have the room to house a top quality inkjet printer nor the patience to deal with various necessities for getting excellent prints (calibrating the printer, different profiles for each paper, keeping them in sync and up-todate, dealing with machine maintenance and periodic problems, and so on). 

Those inkjet labs that I have tried either did not offer printing on papers that interested me for most purposes (e.g. WhiteWall) or others that I tried were too expensive,  and the quality of output that varied from mediocre to poor.

What I would like to find is a printing process that will give me the quality I found so attractive with color prints made on N surface paper from large format film, yet to have that with photos now taken with full-frame or small medium format size cameras. I like to look at a print with the proverbial nose to the print. Not a practical way of looking, but that's what floats my last-century boat :-).

I'm sure inkjet printing has improved since I last tried, but I don't know what labs I should consider, nor the exact paper surface  (although come to think of it there is probably plenty of info on appropriate papers already here on Lula).

I am interested in the Lumjet printing process and also am a little bit interested with WhiteWall's so-called HD process (although WhiteWall offers their 400 PPI process only on glossy paper which I generally don't like).  Lumjet offers various papers types including a type of Matte which might be what I'm looking for.

While the Lumjet process may not interest the vast majority of those here, I am glad the article was published, and I may give Lumjet a try.  While it doesn't seem like Lumjet would fulfill all my needs (restriction on sizes, mounting options), at least it may be useful for some of my purposes, and also perhaps for at least a few others here on Lula.  Even if not,  I personally find it interesting to read in detail about improved processes.

My thanks to Mark Segal, and also to Kevin.

Dan

P.S. Hey, I love those posting verification questions. But arithmetic is just so last-century. How about some questions involving calculus, or quantum mechanics. I need something to challenge my aging and increasingly lazy brain :-)
« Last Edit: February 26, 2018, 06:51:31 PM by photodan19 »
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Mark D Segal

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Re: Lumejet Process Overview
« Reply #21 on: February 26, 2018, 06:52:16 PM »

...................

While the Lumjet process may not interest the vast majority of those here, I am glad the article was published, and I may give Lumjet a try.  While it doesn't seem like Lumjet would fulfill all my needs (restriction on sizes, mounting options), at least it may be useful for some of my purposes, and also perhaps for at least a few others here on Lula.  Even if not,  I personally find it interesting to read in detail about improved processes.

My thanks to Mark Segal, and also to Kevin.

Dan

..................

You are welcome. Glad you found it to be of interest.
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Mark D Segal (formerly MarkDS)
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amolitor

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Re: Lumejet Process Overview
« Reply #22 on: February 26, 2018, 07:10:52 PM »

photodan, if you're in North America, it might be worth noting that you can  just use mpix, which as far as I know uses Durst Theta gear. Miller's the professional side of the house, is rather more clear about what they use. Although they're shy about printers, they do make clear that the papers are RA-4 papers, so they're using someone's led/laser system.

If you do try out both Lumejet and a less, um, hyperbolic option, I think there are plenty of people who'd like to hear your impressions!
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digitaldog

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Re: Lumejet Process Overview
« Reply #23 on: February 26, 2018, 07:31:01 PM »

photodan, if you're in North America, it might be worth noting that you can  just use mpix, which as far as I know uses Durst Theta gear.
Somewhat bad news, they demand sRGB:
https://www.mpixpro.com/help/help.aspx?id=21
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Andrew Rodney
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elliot_n

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Re: Lumejet Process Overview
« Reply #24 on: February 26, 2018, 07:41:57 PM »

Somewhat bad news, they demand sRGB:
https://www.mpixpro.com/help/help.aspx?id=21

Is that really a problem for digital c-types?
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amolitor

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Re: Lumejet Process Overview
« Reply #25 on: February 26, 2018, 07:47:19 PM »

The pro side of the house might do better (Miller's) but I bet not. They're aimed at professionals in the sense of wedding photographers, who (like me) tend to have a pretty blunt instrument take on color management: "does the skin look like skin? does it look like HER skin? we're good to go!"

But mpix is a good cheap way to get an absolute baseline for what these kinds of tech can do for you. It's basically a little more expensive, and (maybe) a little better
than a drugstore print, but it *is* a C-print off a laser printer, not an inkjet. At least, as far as I can tell.

Are all print houses as bloody annoyingly vague about their equipment and methods? They're all vague, blabbering on about their amazing feel and the rich quality of the prints and the vibrancy of the color and jolly little about "We use Durst Thetas and the gamut looks like this and there ya go" or whatever.
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digitaldog

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Re: Lumejet Process Overview
« Reply #26 on: February 26, 2018, 07:50:35 PM »

Is that really a problem for digital c-types?
Yeah, if you're hoping to use the color gamut of the output device. I mean, it's not like sending sRGB to an output device guarantees it will suck, but you're throwing the baby out with the bathwater in the process. Easy to test to (maybe something like this example below will be tested here....):



The benefits of wide gamut working spaces on printed output:

This three part, 32 minute video covers why a wide gamut RGB working space like ProPhoto RGB can produce superior quality output to print.
Part 1 discusses how the supplied Gamut Test File was created and shows two prints output to an Epson 3880 using ProPhoto RGB and sRGB, how the deficiencies of sRGB gamut affects final output quality. Part 1 discusses what to look for on your own prints in terms of better color output. It also covers Photoshop’s Assign Profile command and how wide gamut spaces mishandled produce dull or over saturated colors due to user error.
Part 2 goes into detail about how to print two versions of the properly converted Gamut Test File  file in Photoshop using Photoshop’s Print command to correctly setup the test files for output. It covers the Convert to Profile command for preparing test files for output to a lab.
Part 3 goes into color theory and illustrates why a wide gamut space produces not only move vibrant and saturated color but detail and color separation compared to a small gamut working space like sRGB.

High Resolution Video: http://digitaldog.net/files/WideGamutPrintVideo.mov
Low Resolution (YouTube): https://www.youtube.com/watch?v=vLlr7wpAZKs&feature=youtu.be
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Andrew Rodney
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elliot_n

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Re: Lumejet Process Overview
« Reply #27 on: February 26, 2018, 08:00:13 PM »

Yeah, if you're hoping to use the color gamut of the output device.

Do these devices (digital c-type printers) have a gamut that is significantly bigger than sRGB?
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digitaldog

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Re: Lumejet Process Overview
« Reply #28 on: February 26, 2018, 08:06:45 PM »

Do these devices (digital c-type printers) have a gamut that is significantly bigger than sRGB?
Case in point, three similar and much older printers who's color gamut is much smaller than a modern ink jet (and you're only seeing one 'view' in 3D here).


The red plot is sRGB. Colors are what clip sending sRGB to such devices (if the image contains such colors). Not pretty:
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Andrew Rodney
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elliot_n

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Re: Lumejet Process Overview
« Reply #29 on: February 26, 2018, 08:16:52 PM »

Thanks.

I normally work in Adobe RGB, and when I make digital c-types it's normally the reds that get knocked back the most. The same thing happens when I convert from Adobe RGB to sRGB, so I wondered if sRGB had a similar gamut to the digital c-type. But you've shown that digital c-types can represent blues, greens and yellows that get chopped off by sRGB. Not good for landscape photographers.

(My lab supplies profiles, and asks its customers to make the conversion, so I know what to expect.)
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amolitor

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Re: Lumejet Process Overview
« Reply #30 on: February 26, 2018, 08:18:17 PM »

Even if you've got a crappy little space on output, starting somewhere big and loose gives you a lot more room for squeezing into the little space in the best possible way. I guess.
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digitaldog

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Re: Lumejet Process Overview
« Reply #31 on: February 26, 2018, 08:21:34 PM »

Thanks.

I normally work in Adobe RGB, and when I make digital c-types it's normally the reds that get knocked back the most. The same thing happens when I convert from Adobe RGB to sRGB, so I wondered if sRGB had a similar gamut to the digital c-type. But you've shown that digital c-types can represent blues, greens and yellows that get chopped off by sRGB. Not good for landscape photographers.

(My lab supplies profiles, and asks its customers to make the conversion, so I know what to expect.)
The big differences is in the green primary. But yeah, Adobe RGB (1998) has a larger color gamut and as importantly, something called Gamut Efficiency. What gets interesting is to examine the Lab Gamut Efficiency of differing color spaces. You can see a list on Bruce Lindbloom's excellent site Information About RGB Working Spaces.
Information About RGB Working Spaces

Examine sRGB who's Lab gamut efficiency is a mere 35%, then Adobe RGB (1998) at 50.6% while ProPhoto RGB has a Lab gamut efficiency of 91.2% despite having two primaries (and thus device values) that do NOT define colors (we can't see them).

 
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Andrew Rodney
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Stephen Ray

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Re: Lumejet Process Overview
« Reply #32 on: February 26, 2018, 09:19:26 PM »

I've taken a cursory look at their glossy profiles and they seem to be virtually identical to LightJets, Chromiras, AND Lambdas.

Hmm. I wish them luck.
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digitaldog

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Re: Lumejet Process Overview
« Reply #33 on: February 26, 2018, 09:34:13 PM »

I've taken a cursory look at their glossy profiles and they seem to be virtually identical to LightJets, Chromiras, AND Lambdas.
Good to know! With the same/similar papers, kind of what I'd expect.
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Andrew Rodney
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Mark D Segal

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Re: Lumejet Process Overview
« Reply #34 on: February 26, 2018, 09:36:47 PM »

Elliot, to answer your questions in Replies 24 and 27 directly using the largest gamut Lumejet profile (a bit larger than Lumejet Luster), I've included here several gamut diagrams prepared in Colorthink Pro. They show:

#(3) the Lumejet profile has a different shape from sRGB and in some places exceeds sRGB, therefore files limited to sRGB do not use the full possible gamut of the Lumejet process.
#(4) the Lumejet profile fits comfortably within ARGB(98) gamut, explaining why Lumejet asks customers to deliver their files prepared in ARGB(98) space.

By comparison, the largest gamut printer profile I've ever generated (i1Profiler, i1Pro2) was for Red River San Gabriel Gloss Baryta (very similar to Ilford Gold Fibre Silk). It's gamut shape is different from those of ARGB(98) and ProPhoto RGB. #1 shows that it exceeds ARGB(98) in certain parts of the gamut, while #2 shows that ProPhoto RGB fully encompasses it; hence to take full advantage of the San Gabriel Baryta gamut, one is best advised to prepare ones files in ProPhoto RGB colour space. So one is dealing with quite different gamut conditions for C-type versus a very wide gamut inkjet process. This could have differing implications for different kinds of photos as discussed in my Lumejet article, as well as in other paper and printer reviews I've prepared for this site.
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Mark D Segal (formerly MarkDS)
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digitaldog

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Re: Lumejet Process Overview
« Reply #35 on: February 26, 2018, 09:48:35 PM »

#(3) the Lumejet profile has a different shape from sRGB and in some places exceeds sRGB, therefore files limited to sRGB do not use the full possible gamut of the Lumejet process.
#(4) the Lumejet profile fits comfortably within ARGB(98) gamut, explaining why Lumejet asks customers to deliver their files prepared in ARGB(98) space.
ALL printers have a vastly different shapes compared to all RGB working spaces. All RGB working space have similar and predictable shapes due on the fact they are based on theoretical emissive display, not printers. 
NO Printer can print all of sRGB and thus any RGB working space. Again due to the facts above.
Modern ink jet printers like the Epson shown below have color gamuts, depending on paper of course, that greatly exceed Adobe RGB (1998); they do not comfortably within ARGB(98) Adobe RGB (1998) color gamut.
Red plot: Adobe RGB (1998) vs. my Epson 3880 with luster paper. Again, at least in terms of color gamut and an appropriate working space color gamut, Adobe RGB (1998) doesn't cut it for the Epson and the plots show this Lumejet isn't at all impressive in terms of color gamut compared to that ink jet.
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Andrew Rodney
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amolitor

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Re: Lumejet Process Overview
« Reply #36 on: February 26, 2018, 10:21:32 PM »

Ok, so I am taking another swing at this thing, even though color science makes me all cross-eyed. I'm kind of getting lost in the technicals.

"Every pixel is created as a unique exposure for every one of the 576 RGB LEDs. This is finely controlled by digital circuits that give 2048 grey levels/pixel for Red and Green and 1024 levels for Blue (32bit levels). The individual RGB exposures for each of the 576 LEDs are delivered down the fiber taper and projected in parallel so that they image vertically onto the paper."

Does the print head do 576 pixels in one go, and then go on to the next 576 pixels? Or are all 576 LEDs involved in each pixel? Or, um, is it actually 192 S, 192Gs and 192Bs, doing 192 pixels at a go, or what? The first sentence seems to have been mangled, or maybe I am just persistently not reading it the way it's intended. Either way I cannot make any sense out of what it means.

Slightly later we find:

"4 billion unique colors possible for each printed pixel"

Is this even meaningful? I mean, it sounds sexy, but I'm pretty sure that's orders of magnitude more colors than we can see?

I feel like I could make sense of the analysis of the results, and I understand the bit at the end "these things look good", but the description of Lumejet's process is still pretty opaque.

Also, I have to say that Lumejet's quotation of pixel density in  squares rather than lines (160K vs 90K) sounds disingenuous, albeit accurate. When you state it as 400dpi vs 300dpi it doesn't sound like Lumejet has such an advantage. If they stuck with it, I might let it slide, but literally every other reference is to 400dpi. It's only when they want to seem bigger that they go with the square.

Just for humor, imagine this sentence:

"As a result of this, LumeJet claims that its 400dpi print quality is greater than that of multi-colour inkjet printing at over 4000dpi."

re-written as:

"As a result, Lumejet claims that it's 160K pixels/sqinch print quality is greater than that of multi-colour inkjet printing at over 16M pixels/squinch"

which, while it says exactly the same thing, feels a heck of a lot less convincing.
« Last Edit: February 26, 2018, 10:27:22 PM by amolitor »
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digitaldog

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Re: Lumejet Process Overview
« Reply #37 on: February 26, 2018, 10:27:53 PM »

"4 billion unique colors possible for each printed pixel"
Good catch!
No, it's not possible and it's marketing BS. But we hear this nonsense all the time from lots of companies. We human's can't even see 16.7 million colors. The number is up to debate but far less (I've heard 12 million most often). So what's being discussed here and being incorrectly called colors? Numbers. Device Values. Case in point is this illustration of two device values (numbers) in lowly sRGB that ARE the same color.


For those that wish to understand the vast differences in color and device values, I offer:
http://digitaldog.net/files/ColorNumbersColorGamut.pdf
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Andrew Rodney
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elliot_n

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Re: Lumejet Process Overview
« Reply #38 on: February 26, 2018, 10:42:35 PM »

Given that their maximum print width is 12 inches, is it safe to assume they are using some sort of minilab (Fuji Frontier, Noritsu etc)?
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Stephen Ray

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Re: Lumejet Process Overview
« Reply #39 on: February 26, 2018, 11:45:56 PM »

Does the print head do 576 pixels in one go, and then go on to the next 576 pixels? Or are all 576 LEDs involved in each pixel?

The LED counts only affect the end user if banding is visible when the machine does not expose and advance precisely. Trust that the machine works.

What is more important and easier to understand is, the machine can (or should as many others already do) print pixel-for-pixel from 400 ppi files. Although their website says one cannot see the individual pixels, I'm sure they are mistaken. All these machines easily print discernible individual pixels when the test is provided. Single red, green, blue pixels on white, gray, and black backgrounds are easy to see with a loupe of 8~12 power. Single pixels on white are to be found on ink jets, not so easy to see on gray or black backgrounds. Pixels subsampling is employed also. Lenses may be used also. Common lenses such as Nikon in the case of Chromira LED printers. Thus a digital enlarger exposing typical color photo print material. Awesome, still.
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