Lightroom and ACR: Jagged edges on diagonals

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  • Problem
  • Updated 6 years ago
  • Solved
  • (Edited)
Olympus EP-L1 raw files have serious jagged diagonals. They're visible on sharp curved surfaces but not on straight sharp diagonals from 0o to 45o. Below is a comparison between in-camera jpeg and .ORF converted to DNG in Lightroom 3.3, ACR 6.3. BTW, this is visible on .ORF files as well as DNG. I took these photos with RAW+JPEG at full resolution, highest quality. Notice also how the Bayer decoding affects complex texture.

JPEG


RAW


Please take a look at my dpreview forum thread for more examples and comparisons to other RAW decoders.
http://forums.dpreview.com/forums/rea...

Running LR 3.4 on Mac OS X Lion

Best Regards
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imagerush

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  • feeling kind of jagged

Posted 7 years ago

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Benjamin Warde, Employee

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This happens with raw files from cameras that have a very weak (or non existent) low pass (anti-aliasing) filter. We are working on improvements to our demosacing algorithm that will handle cases like this better.

Thanks,
Ben
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imagerush

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Hi Benjamin

My thoughts exactly.
Most compact cameras have weak low-pass filters in order to get sharp jpegs. Such an improvement to the demosacing algorithm is becoming a priority as the market is flooded with RAW capable compacts.

Thanks!
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Karl Bodin

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Lightroom 4, Ricoh GXR mount A12: the cameraprofile suffers from "jaggies". This camera has no AA filter. Probably there is a mixup with other GXR modules, such as A12 50 mm and A12 28 mm, which have the same sensor (but with a AA filter). Hope I am clear! Please correct profile for GXR mount A12. Many thanks.

This reply was created from a merged topic originally titled
Lightroom 4: Ricoh GXR A12 - camera profile is jaggy.
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Dorin Nicolaescu-Musteață, Champion

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Here's my own example shot with a Nikon D70 and the 18-70 kit lens. In the ACR example, note the difference in rendering between the diagonal blade of dry grass on the right and the more upright (~30 deg) one on the left. In-camera generated preview does not exhibit the problem.



Lightroom 4.3 RC.
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Dorin Nicolaescu-Musteață, Champion

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To be fair to ACR developers, I must say that I would not consider it a flat out bug, but rather a limitation of the demosaicing algorithm. A demosaicing algorithm is always a balancing act. On one hand, between detail and artifacts, quality in different cases patterns, and on the other hand, perhaps, between quality and performance too. So, compromises have to be made.

To illustrate this, I generated a few more renderings with dcraw, using different options. I also add the raw mosaic image for reference.



Note the same 2 pixel jaggies in the default dcraw AHD (Adaptive Homogeneity-Directed) rendering. They are gone with the -f switch (nterpolate RGB as four colors), at the expense of more color artifacts, especially in the near-vertical blade of grass.
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Karl Bodin

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OK! So this is something we have to accept if we are using LR4? No "fix" on the horizon?