Subtle 1" Banding on Mimaki JV3

[John Childs]

Hi Jeff. Welcome to uksignboards. 😀

A shot in the dark – unidirectional or bi?

[Jeffrey Wons]

Hi John,

Thanks for the quick reply.

Definitely uni-directional for the best quality possble.

Jeff…

[Chris Wool]

hi
i have had the ink tube carrier make funny noises as it comes to the end of the head travel. nothing to do with banding thou.

there has been a few people of late complaining of faint banding with magenta cyan a difficult one to pin down.

chris

[David Rowland]

hm.. similar post elsewhere on another forum… turned out to be the Y-Motor bearings.
Although personally not had this problem with our 3yr old JV3

Encoder strip needs to be checked and cleaned with something not melty like water, the encoder sends positional information back to the JV3 and if this is irregular then you get allsorts of weird prints. But Mimaki would have told you that first I suspect.

[Jeffrey Wons]

Dave,

Mimaki did recommend checking the encoder strip. It has never been cleaned and has some dust on it. I am somewhat afraid to clean it as this is a delicate (and expensive) part of the printer. Water you say?? And a soft cloth??

Today I cropped out the guilty area of the poster print which would be the sky. I oriented the print exactly as the total print would have been for the sample run. This means a crop the total width of the file to make the printheads fire along the maximum width of the platen (30" or so).

No Banding!!!!! Another experiment will be to simply re-print the original file and see what happens. Large prints seem to do this while small runs don’t show it near as much.

For some reason the cropped image barely created the noises I am used to hearing; but then again, my printer will do this moaning noise some times and not others. And sometimes it does it on and off during the same print.

I am now investigating a connection between the passes in which the moaning occurs and banding at those areas in the print.

Yes, I am asking for advice as you guys seem to be knowledgeable.

I do have much to offer to the newer members in the way of advice as well. So I am not here to only ask for advice…

Jeff
Expressionary Art

[Jeffrey Wons]

I hate being considered a "newbie." Until I help others and post several hundred threads, I guess that is what I am….

That is cool you guys…

Jeff
EA

[David Rowland]

Ok, the light reads the top part of the encoder strip, i think the print is on the reverse of the strip (i could be wrong)… soft cloth/water seems to work for me.

If you are saying that solid colour blewn up to the width of the printer produced no banding and when normal size does produce banding then what is your image? Is it a scan from a magazine blown up to print, that will cause some kind of banding.

Get the same colour in a 30" rectangle, print that the size of the machine. See what colours it effects.

Also, most importantly, how good is your nozzle print? is it perfect with all nozzles in line.

[Jeffrey Wons]

Dave,

The print is of the Seattle skyline in the early evening so the sky is medium blue with a few clouds in it. I acquired the image from a stock photo website. It came in at 300dpi at around 6" by 10" in size.

Then I began tweaking it in Photoshop and blew it up to 28.5" by 43".
Actually, the whole print is awesome except the light 1" stripes in the sky. I saw this several months ago on another blown up print in the cyan/magenta areas. I am starting with a medium quality image and trying to make it huge.

I’ll clean the encoder strip and maybe swap out the capping station as it is possible that air could be getting in somewhere causing what looks like ink starvation every inch or so on the large areas of cyan/magenta ink duty.

I love my Mimaki, but this has to be resolved.

I appreciate your input,

Jeff Wons
EA

[Jeffrey Wons]

Dave,

I’m sorry, I didn’t answer all of your questions.

My test draw looks normal as it always has. Seems to be lined up.

Also, I re sampled the image up to 720dpi RGB. I need to learn more about color management as this could be a factor perhaps.

The Y-motor is still my first suspicion. Maybe a combination of an old Y-motor, dirty dampers, dirty encoder strip, and air leakage around the rubber seals of the capping station (looks fine though).

My printer is about 18-months old and I have never done maintenance on these areas or replaced these parts. The time is coming for routine replacement of some of these parts anyway I think. Disway washes should help to clear the lines down to the pump.

I’ll share my success on this issue (if I figure it out) with others on this forum.

Jeff………..

[Bill McMurtry]

Jeffrey, I wonder if enlarging the image in Photoshop has caused this banding in the sky dithering? I came across a similar problem some time ago after enlarging an image with a large dithered area – the print output had banding in the dithering. You might try using different methods for enlarging the image – Photozoom Pro has a number of ways of handling image enlargement and does a much better job than Photoshop.

[David Rowland]

so how is other printing or is it this one particular file? you sound experienced if its 2 years old.

[Jeffrey Wons]

Dave & Bill,

I have checked out Photozoom’s website and they use a different engine for blowing up images. Could be an awesome investment to aid in the implementation of enlargement. They go into great detail on the process of adding pixels based on surrounding color values, etc.

In Photoshop, I always go with "bicubic interpolation" and have enabled that feature in Wasatch as well for images that are enlarged in the RIP.

More experiments will be conducted (I had to work all weekend at my regular job so lack of time has been a factor).

Basic solid colors don’t seem to do this on files I create in Illustrator (even blown up a tad).

I have two magnifying "Lupe’s" (10x & 60x-100x) magnification devices that I can use to REALLY see the dots up close. No one knows their printer until they use one of these babies to see every DOT as it is placed on the substrate. You can actually see "dot-gain" and how it is effected by adjusting the head height, etc. from thin to thick on the Mimaki.

My scan wait time is set at 2.7 seconds to allow some drying to occur between passes, 2 overprint for richer saturation.

A simple flashlight shined up close on the guilty area shows weak ink coverage (kind of blotchy). This may very well be a "file" problem. The buildings and highways on the print are darn near perfect with absolutely no banding…

I have learned that in wide format printing, your prints are only as good as you are in manipulating the software and mechanical aspects of the hardware.

Have you guys heard about the new Wasatch 6.1??? It is the only RIP to do 16-bit rendering for better gradients and deeper bit depth…

I am still learning and this forum is the best I have encountered so far.

Jeff
EA

[Jeffrey Wons]

One more note you guys…

The banding is not apparent on the monitor. I have applied filters such as noise reduction, Gaussian blur, and "dust & scratches" to create what appears to be a totally smooth sky in the photo shop file.

Basically I tweaked the heck out of this file and it printed beautifully except for the sky. Isn’t that interesting that no banding occurred on any other area of the print???

I’m beginning to look at this as a combination of perhaps some old parts and color management issues.

Learning all the time, man….

Jeff……

[Bill McMurtry]

Jeffrey, from all that you’ve described I would think that if you cut out the sky area of the photo and replace it with an artificial dithering created in Photoshop then your print output would probably not exhibit the banding. This might prove that the problem is in the image file, even though you can’t see the banding artifact on your monitor.

[Jeffrey Wons]

Bill,

I have contemplated doing this. But never acted on it…..

You are exactly right!! This will happen & I’ll let you know how it comes out.

I know how to separate areas using the "magic wand tool & others." Some mild "blurring" on the edges would finalize separation of the sky and buildings.

Now, to RECREATE the sky that is similar in hues, etc. Custom clouds could be incorporated.

I’ll do a new post on the outcome. Probably a couple of days.

This seems to be the best advice to begin with. THANKS…

Ah Yes, could the importance of color management present itself to a beginner like me on that topic????

Jeff
Expressionary Art

[David Rowland]

Jeff, from what you described the JV3 is working fine, cant see it has anything to do with Y Motor. Recently we blew up a photo in photoshop from digital to full size boards. In the newer Photoshop CS2 range, came two new Image Size compressions, one of them I think is called "BiPolour Smoother" and it works really well.. I ramped it up to an over the top 300dpi in this case.

I remember in my litho days, we did once remove the magenta out of the blue skyline as it made a picture look terrible, skys are quite hard to print.

Are you using the CMYK printer or the CMYK ltC LtM printer? If you convert your document to CMYK, you should get correct colour look from computer to printer, in RGB it will be matched nearest and anything outside of the printers gamut will be cut off.

[Jeffrey Wons]

Dave,

I am using the basic 4-color (CMYK) and will go to 6-color(+Lc & Lm) soon.

Very subtle 1" banding did occur on the "re-created sky" today. It is almost like a white streak every inch or so. Not very noticeable but should not be there.

If you are selling prints, it can’t be there…

Jeffrey Wons
EA