Need Help... Large print artifacts

[charlesttchen]

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Dear friends, while preparing for my photo exhibition, I encountered major problems when trying to print my M9 DNG file to the size of 177cmx100cm. When I try to simulate the print by enlarge the image on my screen to 4:1, I encountered 3 problems:

 

1. There are strange vertical "cubes" on certain middle-lighting areas, not the light areas nor the dark areas.

2. There are strange color artifacts. I removed some of them by using the sense correction in LR. But still....

3. There are some "zebra" stripes in certain area. 

 

Any idea? There's a collector very interested in purchasing this photo and I am eager to resolve the issue. Please help. Thanks a mio.

 

Best Regards

Charles

 

https://drive.google.com/open?id=1JRexPKiUTNgeG24IGKdnJycO1wjuUf0o https://drive.google.com/open?id=1JRexPKiUTNgeG24IGKdnJycO1wjuUf0o

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[jaapv]

That is called moiré, and you either clean it up in Photoshop, quite a bit of work, or live with it.

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[Jeff S]

Also, did you run a nozzle check?

 

Jeff

[jaapv]

He saw it on the screen, Jeff.

[charlesttchen]

Thank you both! So it's the moire, an obvious and true answer. But how about the "cubes" in the photo below? Something to do with the sensor formation?

[david strachan]

So Charles have you tried a print? Screen is very different...it may not show in print.

A smaller proof print is always necessary anyway.

...

Edited June 8, 2018 by david strachan

[Jeff S]

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He saw it on the screen, Jeff.

Next time I’ll ignore the thread title...and read the ‘fine print’.

 

Jeff

[dau]

Thank you both! So it's the moire, an obvious and true answer. But how about the "cubes" in the photo below? Something to do with the sensor formation?

The cubes seem to be caused by the JPEG format. That's what it does when it compresses the image. Try converting the original (raw) image to either JPG or PNG with the compression turned off.

[jaapv]

Next time I’ll ignore the thread title...and read the ‘fine print’.

 

Jeff

[jaapv]

The cubes seem to be caused by the JPEG format. That's what it does when it compresses the image. Try converting the original (raw) image to either JPG or PNG with the compression turned off.

However, if the original image is raw, Lightroom should not produce JPG artefacts on the screen. But David is right that this one might not show up on the print.

Try a test print by cropping a problematic part of the image to the correct enlargement and printing it on a small printer. Otherwise it would be a long session with healing tool, clone tool and blur brush in Photoshop.

 

Another option you might try is using a program like "perfect Resize" to gain your pixel count if the problem is caused by Lightroom at 400%.

https://www.on1.com/products/resize/

 

It is not clear where in the processing process these artefacts have been introduced. If not in the camera, you should look at your raw conversion or your complete workflow.

 

Or use a different raw converter like Raw Therapee. if the demosaicing is at fault

http://rawtherapee.com

 

Or use a different editing software like Capture One or Luminar if there is some other problem in the postprocessing process..

[charlesttchen]

However, if the original image is raw, Lightroom should not produce JPG artefacts on the screen. But David is right that this one might not show up on the print.

Try a test print by cropping a problematic part of the image to the correct enlargement and printing it on a small printer. Otherwise it would be a long session with healing tool, clone tool and blur brush in Photoshop.

 

Another option you might try is using a program like "perfect Resize" to gain your pixel count if the problem is caused by Lightroom at 400%.

https://www.on1.com/products/resize/

 

It is not clear where in the processing process these artefacts have been introduced. If not in the camera, you should look at your raw conversion or your complete workflow.

 

Or use a different raw converter like Raw Therapee. if the demosaicing is at fault

http://rawtherapee.com

 

Or use a different editing software like Capture One or Luminar if there is some other problem in the postprocessing process..

 

Thank you so much for the valuable info. I will try both (print sample + other raw converters). Appreciate.

[charlesttchen]

Sorry.... 

Edited June 8, 2018 by charlesttchen

[charlesttchen]

Next time I’ll ignore the thread title...and read the ‘fine print’.

 

 

Haha U'm so sorry Jeff... I tried to change the topic but couldn't find a way, being new to the group.

[charlesttchen]

However, if the original image is raw, Lightroom should not produce JPG artefacts on the screen. But David is right that this one might not show up on the print.

Try a test print by cropping a problematic part of the image to the correct enlargement and printing it on a small printer. Otherwise it would be a long session with healing tool, clone tool and blur brush in Photoshop.

 

Another option you might try is using a program like "perfect Resize" to gain your pixel count if the problem is caused by Lightroom at 400%.

https://www.on1.com/products/resize/

 

It is not clear where in the processing process these artefacts have been introduced. If not in the camera, you should look at your raw conversion or your complete workflow.

 

Or use a different raw converter like Raw Therapee. if the demosaicing is at fault

http://rawtherapee.com

 

Or use a different editing software like Capture One or Luminar if there is some other problem in the postprocessing process..

Dear Jaap, the problem resolved! I tried rawtherapee/IGV demosaic and it works. Thanks a mio!!!

[gyoung]

The cubes seem to be caused by the JPEG format. That's what it does when it compresses the image. Try converting the original (raw) image to either JPG or PNG with the compression turned off.

Why would anyone print any size let alone very large from a jpeg?

 

Gerry

[charlesttchen]

Why would anyone print any size let alone very large from a jpeg?

 

Gerry

 

Thanks Gerry. I have the original file in DNG and generated a 100m-pixel tiff file for printing. I am sure you are aware that any sizable printing will requite interpolation on pixels. Funny how I found the resize algorithms also make some visible differences. I am glad that I resized it myself rather than blindly trust the resize software in printing service, despite that it's not necessary bad.

[gyoung]

Thanks Gerry. I have the original file in DNG and generated a 100m-pixel tiff file for printing. I am sure you are aware that any sizable printing will requite interpolation on pixels. Funny how I found the resize algorithms also make some visible differences. I am glad that I resized it myself rather than blindly trust the resize software in printing service, despite that it's not necessary bad.

 OK, I thought you were sending a jpeg for printing!  With a 24 mpx camera I haven't had any problems with needing interpolation (up to A2), but when I had only a 12mpx camera I tried doing it using Photoshop, and also letting Lightroom do it 'automatically' I couldn't see any diffrence, so now I let Lightroom handle any mismatch between image resolution and print size and resolution.

 

Gerry