Lightroom and ACR: Black boxes around highlights when using Defringe

  • 1
  • Problem
  • Updated 6 years ago
  • Not a Problem
  • (Edited)
I can't say for sure this is a "bug" or problem., it's just a personal observation. When importing flower images with dew from a Canon 7D (since this is the camera that was used at the time), when I do Chromatic Aberration reduction for the edges of the flowers, it also makes a strange black box around some of the dew drops.
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Mark LaMonica

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Posted 6 years ago

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Dorin Nicolaescu-Musteață, Champion

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Yes, I see.

This is within specs. Boxy artifacts after defringing, usually mean you pushed it too far. Try to narrow the range of purple (or green) hue, as well as dial down the amount.

For this particular image, I am not sure you need any defringing at all.
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Steve Sprengel, Champion

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Is this LR 3's manual CA correction or LR 4's Auto-CA or LR 4's Manual Defringe?

Whichever it is, the operation appears to only desaturate the color fringes rather than pushing the adjacent color into them.
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Dorin Nicolaescu-Musteață, Champion

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Since the specular highlights are white, there's no adjacent color to be pushed into the petals.
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Mark LaMonica

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The top of the flower had major fringing, the boxes were down lower in the dew drops. It was in manual in LR4. Even with no CA applied the box is there, just smaller. Dialing down the purple just reduces the size. I haven't done any experiments with other images from other cameras, this is first time I've seen this in 10 years of Canon digital use. Uploaded the same image in C1Pro6 and no box.
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Dorin Nicolaescu-Musteață, Champion

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Use the local brush with negative defringing to eliminate the boxes.
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Steve Sprengel, Champion

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The manual defringing operation is new with LR 4.1.

Defringing desaturates the color wherever it is and your flowers happen to be purple just like the fringe color.

As an alternative to defringing does painting with a moire adjustment brush work for the top areas? Or do you mean that without any defringing, the boxes are still there?
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Mark LaMonica

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here's the verdict on this issue. I just loaded images taken with several Canon and Nikon bodies, all having dew drops with highlights and some CA on the edges of flowers or leaves. This is the only picture that has this box around a dew drop and even adjusting the amount, it only reduces the box it doesn't eliminate it. It only shows on the images taken on that day with that body. Images on other days with dew don't show it. *Got to love electronics :)
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Steve Sprengel, Champion

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If you turn off Defringing do you see the boxes?

It is the exact color of the flowers, and therefore the exact color of the pixels in that area, not the day or the camera body. LR cannot distinquish between real fringes and the purple flower color next to a highlight. C1 must have a different algorithm.
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Mark LaMonica

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I forgot to mention, that these are the only images I have taken while working directly under high tension wires and they are the only ones I have that show this.
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Dorin Nicolaescu-Musteață, Champion

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Mark, can you share the raw file for us to play?
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Mark LaMonica

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Once the images are processed, I dump the CR2 files. I won't be back there until May next year, but what I will do is shoot more shots like that under similar conditions as well as under the high tension wires. If I can duplicate this, I certainly will upload a CR2 file. I have some roses under similar lighting but a different location and CA reduction worked fine and no black boxes.