How to avoid thin lines turning into dotted or dashed lines in print or display?

[colorflow]

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I did a search on this and nothing showed up. In both printing and monitor displays the lines on a sailboat become dashed lines. This is true on my monitor and in my Epson 3800 prints @280 dpi for various sizes. I also noticed this problem is worse in the Windows 7Screensavers display than Lightroom display.

 

Thanks for your help,

[lykaman]

Hi, try a Anti Moire Filter.. lots on Google..

[ho_co]

Alan--that's not uncommon with JPG. Are you shooting JPG or raw?

[colorflow]

Alan--that's not uncommon with JPG. Are you shooting JPG or raw?

 

Thanks Howard, I am shooting raw. But I print in Tiff with CS3 at 11x17 on Epson 3800. I also see it on my Screensaver displaying Jpeg in Windows 7, but not in LR4 which, of course is not jpeg. So perhaps both jpeg and tiff may have this problem?

[ho_co]

Well, that blows that theory! Sorry, I stand found out!

 

Because of its lossy nature, JPG compression can sometimes cause "jaggies"; but TIFF shouldn't do that.

 

Alan, I'm out of my depth. I know nothing of Windows or of Epson. I wonder if there's something specific to CS3 and DNG files.

 

Do I understand that you are seeing the effect on the monitor and in print, using the same image? If so, I would think there's something wrong with the image itself.

 

Can you post an example?

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What software and procedures are used for the re-scaling of the images? In the case of the Windows screen saver, I would suspect that Windows re-scales the image without interpolating.

[colorflow]

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Here is an example direct out of LR3 conversion to jpeg.

 

 

Please let me know if you see the ships' lines turned into dotted and dashed.

Thanks

[colorflow]

What software and procedures are used for the re-scaling of the images? In the case of the Windows screen saver, I would suspect that Windows re-scales the image without interpolating.

 

Howard and Philipp, I pp the dng file in LR3, Export as Tiff and open in CS3, then print on Epson 3800 at 240dpi and see jagged lines.

 

Also I Export in LR3 as jpeg with either no restrictions on file and pixel size, or restrict to less than 2Mb. Both files show terrible dotted and dashed lines when displayed in Windows screensaver or viewer.

 

I have not tried scaling to the exact pixel size of my screen. Do I need to do that? In any case I assume CS3 would do the proper scaling for the 3800.

 

Again, the lines appear fine in either LR or CS. I am not so concerned about any Windows display issues. But the print?

 

Thanks for your interest to help.

[colorflow]

The problem with the Windows display was solved by using my monitor's pixel width and height when exporting from LR. No more jagged lines. Thanks for jogging my brain Philipp.

 

So probably the same issue with the print. But how do I match pixel dimensions to dpi and print size? Doesn't CS3 do that automatically?

[k-hawinkler]

Alan,

 

Gorgeous image.

I looked at the image in its largest size on my MacBook Pro.

No jaggies, but I see a moiré patterns in the lines of the large ship in front and one broken line for sure.

 

Best, K-H.

[pop]

The image on Picasa has the colored moiré effect at its full scale which k-hawinkler also mentioned. With the slider near - say - 80% of its range there are some serious jaggies in the lines of the larger boat.

 

I'm using Google's Chrome browser in Ubuntu Linux.

 

At times I succeed in getting rid of jaggies by blurring the image by a very small amount before downscaling.

 

There's a very good introduction to the topic in this very subforum: http://www.l-camera-forum.com/leica-forum/digital-post-processing-forum/115989-digital-printing-pixels-resolution-resampling.html

[colorflow]

Thank you all for your feedback. So it seems the pixel size of the file need to be downres'ed to match the display device in order to properly display thin angled lines. At least in Windows. Didn't know that.

 

I probably need to do that for the print as well. I was printing a 8.5x12.75in image at 240dpi of a ff M9 file which results in 408ppi and thought that would be ok. But I got dashed lines. Maybe I need to downres to match before printing?

[ho_co]

Alan, as I said before, I'm out of my depth here.

 

Seeing the picture on my screen, my first guess was that the defect is caused by something similar to what causes moiré. But that can't happen with lines as large as these IMHO. That happens on the scale of threads of fabric, not quarter-inch lines like this.

 

I don't know what to suggest. Epson printer owners typically go through all sorts of machinations to get the "proper" resolution to the print. Ctein on TOP maybe a year ago tried various routes to getting the best print and ended up saying any differences were too subtle for him.

 

So here's the upshot from my side: On my screen, some of the lines seem to break, leaving a magenta smear on one side of the break and a cyan one on the other. Other lines, more nearly vertical, are dark for a ways, then magenta, then cyan.

 

I think it's a bad sensor or a bad readout from the sensor. I think you should send this link to Leica's tech people and ask them. My guess is that correction will only come by sending the camera to Leica. I think I've seen one similar case on the forum, though it seemed much worse either due to the subject (tree branches) or because the sensor was already worse than yours.

 

I think just showing the file to Leica will get a firm answer. Wow, this is really a strange one, but you shouldn't be getting what you're getting.

[colorflow]

Howard, now you got me worried. I just got rid of the dashed/dotted lines by matching pixel dimensions to my screen, but the moire like stuff is still there, even in LR with the dng file. I will email Leica NJ the dng file and see what they say. I am going to see if I can dig up some similar photos shot with M8 and M8.2.

[colorflow]

Howard, again thanks for your input. Did a quick look at similar photos taken in the past. Seems this is the worst case. Others taken with this M9 show some color fringing stuff but not as bad. Likewise for ones taken with M8 and M8.2. They all show some color fringing/moire like stuff along the lines at high magnification when you are looking for them. Shots taken with Sony A900 and Zeiss lens show almost no such artifact but there if one really looks for them.

 

So I am still hoping this is due to either ca or moire from the texture of the lines. This one is the worst perhaps due to the fog which disperses/magnifies the anormaly? The Lux 35 asph does ca more than say the Cron 35 asph in my experience.

 

Will investigate more tomorrow. Anyway I sent dng to Leica NJ.

[ho_co]

Alan--

Try shooting the branches of a tree against the sky--if your part of the country still has bare branches.

 

In the previous case on the forum, this kind of problem was concentrated in two large areas of the image field, as revealed by a tree shot like that.

 

I hope I'm wrong, but my M8 doesn't do what I see here.

 

Part of it is matching the resolution to the screen, particularly with lines so close to vertical, but that wouldn't appear on the print.

 

I think your example is rather subtle; I'm glad it is the worst you could find.

 

Good luck, and do let us know what NJ says. I hope they dump my argument into the garbage!

[colorflow]

Here is the response from Solmes:

 

“This is due to the combination of our high performance lenses and “no moiré filter”

If the lines hits exactly 1 Pixel width, it is tough to find the right color interpolation.

The positive effect is, that you see a line that is sharper than from any other camera, but the side effect is, that in some cases these color moiré effects can occur.”

 

“These artifacts are very sensitive to the image processing algorithms, therefore it is worth trying to use another RAW converter in this case, or some different settings in the RAW converter.”

[ho_co]

I'm surprised and disappointed to hear that, Alan.

 

I think the person answering your email may be in error, as I said above. But that's also what post #2 says.

 

I'd try another raw converter and see if you get the same result. And see whether the effect appears on images with other than straight and thin lines.

 

But I'm quite likely wrong, and can't disprove what they say.

 

What about shooting the same again, both focused on the lines and slightly defocused. If it's moiré, there shouldn't be a discontinuity on the defocused lines, should there?

 

Sorry for the response, but very glad that you reported it here.

[colorflow]

Howard, the discontinuity or dashed/dotted lines is separate and independent from this moire issue. It is not in the raw file and is only there in Windows 7 displays if I do not downsize the pixel size. The problem is gone if I downsize to my monitor size in LR3 when I export as jpeg. I have not had a chance to try the same with print since I am away from my 3800 for a while.

 

The moire is in the dng file as imported by LR3. I have not seen this effect other than the well known "polyester tux" artifacts. I have seen it in other M9 sailboat shots, but this is the worst. I don't have another converter so can't test that theory. I can upload the dng file to Safari if you care to play with it.

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[ho_co]

Alan, just for curiosity's sake, I'd like to see the raw file.

 

I'm not sure how to go about getting it here, but I'm game.