SilkyPix 6 processing examples - Colour Distortion & Lat. CA

dosdan · 12-14-2015, 02:51 PM

Here are 2 examples of processing in SilkyPix Developer Studio Pro 6. The hand-held raw shot of an Australian Magpie was taken with a K-3 & Sigma 70-200/F2.8 II HSM. 1/400s, f/5.6, ISO400, 200mm FL.

In 100% zooms, I noticed blue-green colouration on the chest feathers. Initially I thought this might be moiré, (I had not switched on the AA-filter simulator in the K-3), but SP's Reduce Moiré option didn't remove it. I found under the NR controls that the Colour Distortion slider set to 78 removed enough of it to satisfy me. The 100% comparison below has the adjusted version on the left.

This colouration does not appear to be lens-specific. I get the same problem with the same subject with a DA* 60-250/F4. Perhaps it is related to the demosaicing method SP uses.

This Sigma lens showed significant Lateral Chromatic Aberration with this subject. Lat. CA is most obvious when looking near the edges of the image. Here's a 400% processing comparison of a claw near the bottom.

And a 200% comparison of the beak near the top of the frame.

After developing the raw as a 16-bit TIFF, I did some further processing in PaintShop Pro X7:

Mild Clarity increase
Mild Local Tone Mapping
Topaz Labs Detail 3 sharpening plugin
After resizing, USM 0.6, 30%

Finally here's the result and a 100% crop of the chest feathers.

Dan.

Last edited by dosdan; 12-14-2015 at 05:28 PM.

**jbinpg** · 12-14-2015, 03:40 PM

Dan - Iridescence is commonly found on black-feathered birds here in w. N. America due to refraction of reflected light by the barbules of the feathers. I suspect that is what you are seeing in your images. Same process that gives the glowing gorgets to the New World hummingbirds.

Jack

dosdan · 12-14-2015, 04:10 PM

Jack, thanks for the suggestion that iridescence of the feathers is the cause of the colouration, rather than a demosaicing method artefact. I don't think this is the case as I would have noticed it outside photography - I look at magpies a lot. I plan to test this soon by shooting a magpie in RAW+ (raw & JPEG).

Dan.

kh1234567890 · 12-14-2015, 05:06 PM

Originally posted by dosdan

This Sigma lens showed significant Lateral Chromatic Aberration with this subject. Lat. CA is most obvious when looking near the edges of the image. Here's a 400% processing comparison of a claw near the bottom.

Handling and correction of CA is one of the major failings of Silkypix SP6. Basically you are stuck with a manual hit-and-miss adjustment after demosaicing. Sometimes you can be lucky and have a suitable bit of image in one of the corners to use.

SilkyPix SP7 is out in Japan but still seems to have the same problem. And still no lens profiles. These days I tend to use PS (ACR) or Raw Therapee more and more instead of SP6. Shame, since noise and colour handling are better in Silkypix.

12-14-2015, 02:51 PM	#1
dosdan Pentaxian Join Date: Dec 2007 Location: Brisbane, Australia Photos: Gallery \| Albums Posts: 1,741	SilkyPix 6 processing examples - Colour Distortion & Lat. CA Here are 2 examples of processing in SilkyPix Developer Studio Pro 6. The hand-held raw shot of an Australian Magpie was taken with a K-3 & Sigma 70-200/F2.8 II HSM. 1/400s, f/5.6, ISO400, 200mm FL. In 100% zooms, I noticed blue-green colouration on the chest feathers. Initially I thought this might be moiré, (I had not switched on the AA-filter simulator in the K-3), but SP's Reduce Moiré option didn't remove it. I found under the NR controls that the Colour Distortion slider set to 78 removed enough of it to satisfy me. The 100% comparison below has the adjusted version on the left. This colouration does not appear to be lens-specific. I get the same problem with the same subject with a DA* 60-250/F4. Perhaps it is related to the demosaicing method SP uses. This Sigma lens showed significant Lateral Chromatic Aberration with this subject. Lat. CA is most obvious when looking near the edges of the image. Here's a 400% processing comparison of a claw near the bottom. And a 200% comparison of the beak near the top of the frame. After developing the raw as a 16-bit TIFF, I did some further processing in PaintShop Pro X7: Mild Clarity increase Mild Local Tone Mapping Topaz Labs Detail 3 sharpening plugin After resizing, USM 0.6, 30% Finally here's the result and a 100% crop of the chest feathers. Dan. Last edited by dosdan; 12-14-2015 at 05:28 PM.

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12-14-2015, 03:40 PM	#2
jbinpg Site Supporter Join Date: Mar 2008 Location: Prince George, BC Photos: Gallery \| Albums Posts: 3,546	Dan - Iridescence is commonly found on black-feathered birds here in w. N. America due to refraction of reflected light by the barbules of the feathers. I suspect that is what you are seeing in your images. Same process that gives the glowing gorgets to the New World hummingbirds. Jack

12-14-2015, 04:10 PM	#3
dosdan Pentaxian Join Date: Dec 2007 Location: Brisbane, Australia Photos: Gallery \| Albums Posts: 1,741 Original Poster	Jack, thanks for the suggestion that iridescence of the feathers is the cause of the colouration, rather than a demosaicing method artefact. I don't think this is the case as I would have noticed it outside photography - I look at magpies a lot. I plan to test this soon by shooting a magpie in RAW+ (raw & JPEG). Dan.

12-14-2015, 05:06 PM	#4
kh1234567890 Veteran Member Join Date: Sep 2010 Location: Manchester, UK Photos: Gallery Posts: 2,653	Originally posted by dosdan This Sigma lens showed significant Lateral Chromatic Aberration with this subject. Lat. CA is most obvious when looking near the edges of the image. Here's a 400% processing comparison of a claw near the bottom. Handling and correction of CA is one of the major failings of Silkypix SP6. Basically you are stuck with a manual hit-and-miss adjustment after demosaicing. Sometimes you can be lucky and have a suitable bit of image in one of the corners to use. SilkyPix SP7 is out in Japan but still seems to have the same problem. And still no lens profiles. These days I tend to use PS (ACR) or Raw Therapee more and more instead of SP6. Shame, since noise and colour handling are better in Silkypix.