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Author Topic: increasing color density  (Read 4157 times)
Damir
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« Reply #20 on: January 26, 2011, 03:55:24 AM »
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Ernst

can you please give us a link to the HP documents that you are talking about?

Interesting method - double printing - I will try it on my Z with slight change on procedure, I will try it like this:

load roll
print
cutter off
unload roll
load roll
print again

if Z load roll at the same position every time this may work - not that I need it but I am curious what is effect, also how precise Z loads paper.

Damir
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Ernst Dinkla
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« Reply #21 on: January 26, 2011, 04:35:50 AM »
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Ernst

can you please give us a link to the HP documents that you are talking about?

Interesting method - double printing - I will try it on my Z with slight change on procedure, I will try it like this:

load roll
print
cutter off
unload roll
load roll
print again

if Z load roll at the same position every time this may work - not that I need it but I am curious what is effect, also how precise Z loads paper.

Damir

I don't think all are there, you have to go into the maze of HP's webpages to see more recent versions:

http://z3100users.wikispaces.com/HP+Tech+Newsletters

Little chance to get it right with a roll loaded. Put two register tabs at the front of the printer, blue line aligned, load paper sheets a bit tilted so the printer will ask you to align them to the blue line, align them to the tabs and to the blue line at the right. The last doesn't need a tab as the sensor on the head will measure the edge anyway. In that case the sheets will be in register. You can adjust  one tab a bit to get the edge parallel to the image which is important if this method is used to print double sided. In that case the print page should be horizontally symmetric on the sheet too. There must be a thread somewhere with pictures of the tabs I made.

The paper load method for deckled edge sheets will ask you right away to align to the blue lines but has a wider tolerance in media position measuring.


met vriendelijke groeten, Ernst Dinkla

Try: http://groups.yahoo.com/group/Wide_Inkjet_Printers/
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Brian Gilkes
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« Reply #22 on: January 26, 2011, 04:57:21 AM »
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High DMax is not a Holy Grail. It is more important that the shadows look deep and rich. This is partly facilitated by very good profiles that keep colours as pure as possible , not murky. Lots of factors come in here such as necessity to multiple read dark patches, use of polarizing filters, and how finely defined are the spectral captures.,. Most commercial units don't come even close to what is possible. Multiple printing is a great idea. I think this was possible with Iris printers.On Epsons you can lay more ink by using the highest resolution setting. Most undulating paper hassles are solved with a few days drying. Of course if you have pooling there is not much point.
 If anyone knows how to achieve exact registration on an Epson or Canon printer I would love to hear from them. Ernst's procedure on HP is interesting. Ernst, how accurate is this method? Do you get any slew? On an Epson I get better results with rolls. Sheets maintain horizontal register but drift vertically.
Cheers,
Brian
www.pharoseditions.com.au
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RHPS
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« Reply #23 on: January 26, 2011, 05:19:26 AM »
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I suppose that all those findings are kept secret. Even though one would have to tweak and fine tune color density, paper thickness and drying time settings, it would be VERY nice if some could give hints for values, in order to get close to it (x880 Epsons with K3VM is my combo ;-). It's really not that I'm lazy, or would not like to do it, it's just that I outsource the profile making to the very best people I can find, 'cause they always do a better job than me.
As other posters have said, the optimum depends entirely on the printer/ink/paper combination, so my results probably will not help you. But, FWIW, I am using InkjetFly ink in my 3800 and my optimized setting for Harman Gloss Baryta is +20%. With Ilford Smooth Pearl I can only go to +10% before I begin to see micro-pooling in the print, at least without increased drying time. As you can see, these increases are quite modest but they do give worthwhile increases in Dmax and overall shadow "quality".

I use a sort of hybrid method to find my optimum but it does involve spectro measurements so probably not useful for you. First I print an ink separation file with K only using QuadTone RIP.  This tells me the maximum black (measured) that I can achieve with the particular ink/paper combination. I then use the method described at http://www.hermitage-ps.co.uk/#q7 to do test prints at different ink levels. For each one I compare the black level with my maximum achieved in QTR and also ensure that no other problems are visible at that level. I could of course use this method for all the colours, but I am more concerned with B&W, and my experience is that measuring the black ink works well enough for colours too.

I thnk the problem you may have without suitable measuring equipment is in determining maximum Dmax and chroma, although you could probably use a scanner to do this. However you do it, it's not a trivial exercise, and until you profile the combination you can never be certain that it gives you any improvement.
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Scott Martin
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« Reply #24 on: January 26, 2011, 10:18:08 AM »
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Can you suggest a relatively inexpensive application for the Mac that will do this?

Apple's ColorSync utility is unfortunately not very good at this. Although I'm fond of a few expensive applications (ColorThink and GamutWorks), the PerfX 3D Gamut Viewer is a decent free alternative. http://mac.sofotex.com/downloads/d136148.html
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Scott Martin
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« Reply #25 on: January 26, 2011, 10:30:46 AM »
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High DMax is not a Holy Grail. It is more important that the shadows look deep and rich. This is partly facilitated by very good profiles...

Yes, I like what you're saying! Different profiling packages handle the "approach to black" differently which plays an effect upon the perception of Dmax, shadow detail, and overall contrast. For years I've been impressed with how Monaco Profiler deals with this "approach to black" relative to ProfileMakerPro and other profiling applications. It's hard to talk about it here but when you've got side by side comparison prints made with these two applications you can really see what we're talking about. The internal curves inside ICC profiles can have a big effect on making shadows "look deep and rich" as you put it.

On Epsons you can lay more ink by using the highest resolution setting. Of course if you have pooling there is not much point.

With pigmented inks (but not solvent!) there is an exact point at which you've achieved the greatest saturation point (chroma) with each ink without causing pooling or loss of shadow detail. Any more and you'll get disappointing results. Finding this exact point is tricky, and there are various ways of doing so - several of which have been mentioned here. I'm actually a big fan of using ColorBurst's chroma graphing tool for finding this point, regardless of what printing process is being used (driver, RIP,etc). I've encouraged a few software developers to come up with a tool for doing this but, so far, there's not much interest in such a niche product.




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Scott Martin
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« Reply #26 on: January 26, 2011, 10:36:52 AM »
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I use a sort of hybrid method to find my optimum but it does involve spectro measurements so probably not useful for you. First I print an ink separation file with K only using QuadTone RIP.  This tells me the maximum black (measured) that I can achieve with the particular ink/paper combination.

Great for B&W, not great for color.

I thnk the problem you may have without suitable measuring equipment is in determining maximum Dmax and chroma...

When analyzing ink limits for color channels DMax is irrelevant - it's all about chroma. The differences can be subtle but important. I wish there were some commonly available simple GUI tools for this. I use ColorBurst's chroma linearization tool to analyze this, even when I'm printing with a driver without ColorBurst.
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Ernst Dinkla
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« Reply #27 on: January 27, 2011, 02:42:21 AM »
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High DMax is not a Holy Grail. It is more important that the shadows look deep and rich. This is partly facilitated by very good profiles that keep colours as pure as possible , not murky. Lots of factors come in here such as necessity to multiple read dark patches, use of polarizing filters, and how finely defined are the spectral captures.,. Most commercial units don't come even close to what is possible. Multiple printing is a great idea. I think this was possible with Iris printers.On Epsons you can lay more ink by using the highest resolution setting. Most undulating paper hassles are solved with a few days drying. Of course if you have pooling there is not much point.
 If anyone knows how to achieve exact registration on an Epson or Canon printer I would love to hear from them. Ernst's procedure on HP is interesting. Ernst, how accurate is this method? Do you get any slew? On an Epson I get better results with rolls. Sheets maintain horizontal register but drift vertically.
Cheers,
Brian
www.pharoseditions.com.au


Like Onsight mentions a good profiler program will handle the shadows, if the Dmax black has no dotgain/bleeding the shadows should fit properly. With matte papers I like to have the highest Dmax possible on that paper, the HPs do that nicely. With gloss papers Dmax is less an issue as the black density is in general at a high level already and I have some doubts whether all spectrometers measure correctly beyond 2.4 D.

Accuracy is excellent for dual sided printing (0.5 mm at most), good enough for hard edge art (silkscreen simulation) double run, the last not enough for photo quality in my opinion. For dual sided printing I can start with rolls, let the printer pull some length first and reroll again, cut the leading edge of the roll too and then start printing the print pages that have some extra white at the top so they can be used again as sheets on the machine. Printer cuts accurate enough. The other run as sheets I place the cut leading edge against register tabs at front and make sure the print page is centered correctly left-right. There are some tricks for the last. If I would use rolls for both sides I can be sure that the print page shifts left or right up to a mm and on the length it wouldn't work either.


met vriendelijke groeten, Ernst Dinkla

New: Spectral plots of +230 inkjet papers:
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm



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terrywyse
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« Reply #28 on: January 27, 2011, 03:09:59 PM »
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Also note that increasing or decreasing the ink density when making a profile target will tend to get the increase/decrease profiled out. There is an optimal settings and that will work the best for making profiles.

Jeff is exactly correct on this.....increasing the print density/ink volume and re-profling will only cause the profile conversion to compensate for this and reduce the ink levels accordingly. The only time where this is NOT true is if the increased print density results in a wider gamut print profile....and an actual image that will take advantage of this extra gamut.

Quote
With Epson paper, it's really not useful to do anything with ink settings other than subtle tweaks...with 3rd party paper, it is useful to work the settings to optimize the ink density prior to making profiles because 3rd party papers don't necessarily fall into the Epson Media settings exactly. But simply increasing the ink density to pump more in onto the paper will not always be useful (and often causes more problems).

What I do is run through several media settings that I think will generally be in the ballpark and then look at the resulting profiles in something like ColorThink Pro. Gamut volume,  gamut boundaries and tonal distribution in the primaries/secondaries will usually tell you what is the correct media setting for your paper.

As far as increasing "density", I'll reiterate what Scott Martin pointed out.....increasing DENSITY does not necessarily increase COLOR. In more correct "colorimetric" terms, once you've increased the ink volume to the point where the chroma (saturation) has peaked and starts to fall off, increasing the ink volume further only results in more ink "darkness" (density, L*, whatever) and only serves to oversaturate the paper with ink (wrinkles like you experienced).

The only think I can suggest if you want to go this route is getting a tool such as ColorThink Pro that will allow you to look at profiles with different ink adjustments to help you determine where the optimum or peak chroma values occur.

If you REALLY want control over the ink volume, you should consider getting yourself a CMYK RIP that allows direct control over per-channel ink limiting and such. With good technique and some knowledge on your part, a CMYK RIP can give you finer control over ink settings and not restrict you to a vendor's driver settings. ColorBurst X-Photo is one such RIP that gives you that kind of control.

Terry
« Last Edit: January 28, 2011, 08:39:54 AM by terrywyse » Logged

Terry Wyse, WyseConsul
day job...Color Management Consulting
on the side....photoWyse, photography and fine prints
G7 Certified Expert (but that depends on the day)
Nino Loss
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« Reply #29 on: January 28, 2011, 06:53:43 AM »
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Thank you all for all those knowledgeable posts!

I will try to find this sweet spot where the increase in color density and other media settings will produce the largest gamut. I will try to build different profiles and look at them with a gamut viewer.
As I outsource the profile making, I
ve only got a scanner and Monaco EZcolor to do that for he moment. I definitely plan on investing in an i1 Pro in the future. Is there any chance that I can "see" something with the combination that I have got right now? I would still let my profiles be made.

regards
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madmanchan
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« Reply #30 on: January 28, 2011, 08:39:18 AM »
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Just be careful that when you're increasing Color Density (or other similar settings in the driver) that you're not making color gradations rougher. For example, transitions between deep yellows and deep greens (e.g., a large smooth transition between an out-of-focus yellow tulip and green background) can be problematic with too much ink.
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Scott Martin
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« Reply #31 on: January 28, 2011, 09:11:22 AM »
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If one focuses on find the chroma/saturation plateau, everything else will follow, including color gradations. Excellent color profiles, of course, play a huge role in these color gradations. Less than the best profiling software can produce disappointing color gradations at several color density settings.

Assuming one is using the best color profiling technology available (which IMO means Monaco Profiler and i1Profiler), one only needs to focus on finding the chroma/saturation sweet spot while avoiding pooling and "ink smudging". My experience suggests that all other subjective visual observations should be ignored, including color transitions and the apparent loss of shadow detail that the profile will deal with. Of course, colorimetricly analyzing and finding the chroma/saturation sweet spot is a tricky thing for most people, because it can't be done by eye - it requires spectrophotometers, software and willingness to conquer the learning curve.

People like Terry Wyse here know this well, because the process of determining per channel and total ink limits, linearization and profiling with a RIP is a real craft that takes years to master. In the process, it teaches you more about inkjet technology that one can ever get from just using printer drivers that have these ink limits, linearization curves and separation parameters baked in.
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