ianman Posted December 21, 2009 Share #1 Posted December 21, 2009 Advertisement (gone after registration) Hello, This is a pic of my wolfhound taken last weekend. I have noticed some colour artefacts appearing in some of the photos. Can anyone shed some light on whats going on here ? My first thought is that it could be sunlight shining through droplets in her fur and that they are therefore not artefacts at all, but then I noticed some (but less) such artefacts in fur that is not in direct sunlight... however they do seem to appear only in areas that are in perfect focus. By the way, the lens used is a 35 Cron asph. Thanks, Ian Link to post Share on other sites More sharing options...
Advertisement Posted December 21, 2009 Posted December 21, 2009 Hi ianman, Take a look here Colour artefacts ?. I'm sure you'll find what you were looking for!
Luuk Posted December 21, 2009 Share #2 Posted December 21, 2009 Ian, This artifacts may be caused by sharpening color information in your file. Sharpening just the luminosity data make it dissapear. BTW what is this jpg or DNG (what converter)? Luuk Link to post Share on other sites More sharing options...
logaandm Posted December 22, 2009 Share #3 Posted December 22, 2009 I suspect Moire. Link to post Share on other sites More sharing options...
FrancoisG Posted December 22, 2009 Share #4 Posted December 22, 2009 I have experienced the same, when to much sharpening is applied. Link to post Share on other sites More sharing options...
adan Posted December 22, 2009 Share #5 Posted December 22, 2009 New breed. The Rainbow Wolfhound. Seriously, it looks like moiré to me, too. The brown hairs are so thin that they don't get recorded by alternating red, blue and green pixels in the Bayer checkerboard, so they pick up artificial color tints as they cross the borders between pixels. Most digital cameras have a faint blurring filter on the front of the sensor to fuzz out fine details like hair to avoid this - Leica left out such a filter to improve sharpness, but the price is occasional color effects like these. There are various ways to reduce moiré effects in post-processing, if they are actually visible in a print. Link to post Share on other sites More sharing options...
george_b Posted December 22, 2009 Share #6 Posted December 22, 2009 There are various ways to reduce moiré effects in post-processing, if they are actually visible in a print. Any offers where I can research reducing moire? When I looked the othe day most suggestions seemed quite tedious, is it built into ACR5.6, CS4 or LRx? Link to post Share on other sites More sharing options...
Ario Arioldi Posted December 22, 2009 Share #7 Posted December 22, 2009 Advertisement (gone after registration) Any offers where I can research reducing moire? When I looked the othe day most suggestions seemed quite tedious, is it built into ACR5.6, CS4 or LRx? Capture One PRO has a tool to remove moirè. Cheers, Ario Link to post Share on other sites More sharing options...
jaapv Posted December 22, 2009 Share #8 Posted December 22, 2009 And Capture One is , in general, better at removing these artefacts than Adobe products, also in the LE versions. Link to post Share on other sites More sharing options...
Guido Posted December 22, 2009 Share #9 Posted December 22, 2009 Any offers where I can research reducing moire? When I looked the othe day most suggestions seemed quite tedious, is it built into ACR5.6, CS4 or LRx? Photoshop: Select color picker - choose a typical brown color in the fur region Select brush, change to "Hue" mode Paint over color artifacts Link to post Share on other sites More sharing options...
adan Posted December 22, 2009 Share #10 Posted December 22, 2009 For DNGs, increasing the color noise reduction setting - in ACR, and I presume, LightRoom - will often blur the chroma (color) enough to blend these kinds of artifacts back into the surrounding luminance/brightness/underlying B&W image. Without blurring the sharpness overall. In the "lens corrections" pane, using the de-fringing settings can also tone down or eliminate moiré color effects of this kind. In Photoshop, running a median filter or light gaussian blur filter (on the order of 3 pixels radius), and then "Fading" the filter ("Color", 100%) has a similar effect, blending the artifacts into the surrounding color (and the surrounding color into the artifacts). Here's how the original post looks via the median/fade color technique (settings exagerrated to account for the magnified image of the pixels): Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/107409-colour-artefacts/?do=findComment&comment=1160351'>More sharing options...
ianman Posted December 22, 2009 Author Share #11 Posted December 22, 2009 Ian, This artifacts may be caused by sharpening color information in your file. Sharpening just the luminosity data make it dissapear. BTW what is this jpg or DNG (what converter)? Luuk Hi Luuk, I'm using Aperture. It's the DNG file. I opened the file in Capture One and increased the Color noise reduction and that got rid of these artefacts. I don't think Aperture has this setting ?! Also LR seems to do a good job but I really can't stand that application, it's so slow (on a MacBook Pro 2.8 Ghz with 4GB ram) and it's UI is a disaster. Ian Link to post Share on other sites More sharing options...
ianman Posted December 22, 2009 Author Share #12 Posted December 22, 2009 New breed. The Rainbow Wolfhound. Seriously, it looks like moiré to me, too. The brown hairs are so thin that they don't get recorded by alternating red, blue and green pixels in the Bayer checkerboard, so they pick up artificial color tints as they cross the borders between pixels. Most digital cameras have a faint blurring filter on the front of the sensor to fuzz out fine details like hair to avoid this - Leica left out such a filter to improve sharpness, but the price is occasional color effects like these. There are various ways to reduce moiré effects in post-processing, if they are actually visible in a print. I haven't printed the image yet, but I agree they probably wont even show up. I'm not too worried about this. Although I have no experience doing pp and such, I am still wondering if this is moiré. I mean would that also make her nose light up like a christmas tree (see below) ? Could it not be some sort of refraction ? Link to post Share on other sites More sharing options...
adan Posted December 23, 2009 Share #13 Posted December 23, 2009 Yep. Overlay fine contrasty details that are close to the size of the imaging pixels onto a Bayer color pattern and - instant Xmas tree! Technically, these color effects on small single details are a form of aliasing, and "moiré" perhaps should be reserved for the broader arcing patterns that occur with brick walls or cloth, and look more like classic moiré: Moiré pattern - Wikipedia, the free encyclopedia Aliasing - Wikipedia, the free encyclopedia But they are both manifestations of the same thing - aliasing of fine detail that is smaller than the "Nyquist limit" and thus gets under-sampled, creating artifacts. Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/107409-colour-artefacts/?do=findComment&comment=1160931'>More sharing options...
t024484 Posted December 23, 2009 Share #14 Posted December 23, 2009 This is even more accurate. The demosaicing is performed bilinear, as LR is using. Hans Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/107409-colour-artefacts/?do=findComment&comment=1161191'>More sharing options...
sandymc Posted December 23, 2009 Share #15 Posted December 23, 2009 This is even more accurate. The demosaicing is performed bilinear, as LR is using. Hans] While I'm not disagreeing that demosaicing can and does results in color artifacts, LR doesn't use bilinear conversion, which is pretty primitive. Adobe have never specified what the algorithm actually is, but an "AHD like" algorithm seems likely as LR sometimes produces the same maze pattern artifacts that AHD produces. Sandy Link to post Share on other sites More sharing options...
jaapv Posted December 23, 2009 Share #16 Posted December 23, 2009 The OP is using aperture. Most posts on the subject we see in this forum come from Aperture users, I find. Link to post Share on other sites More sharing options...
ianman Posted December 23, 2009 Author Share #17 Posted December 23, 2009 The OP is using aperture. Most posts on the subject we see in this forum come from Aperture users, I find. Indeed, and right now I'm thinking about changing my workflow. Maybe import from card into Capture One and then export to tiff for be able to use Nik software. I have taken another look at LR and actually it's not as bad as I remembered. Also for the speed issue, a colleague noticed that by default it was set to use 32 bit (on a mac anyway) I have switched it to 64 bit but not tested yet. LR3 beta is 64-bit by default. Link to post Share on other sites More sharing options...
jaapv Posted December 23, 2009 Share #18 Posted December 23, 2009 My workflow is C1 5.0 pro --> 16 bit TIFF --> CS4 and I am very happy with it. Link to post Share on other sites More sharing options...
Manicouagan1 Posted December 23, 2009 Share #19 Posted December 23, 2009 Are these artifact showing up in both M8 and M9 files? If the cause is something to do with the Bayer array, the size of the pixels, and the lack of an antialias filter, I would think files from both cameras would show similar features. I process my M8 files using Apple's Aperture and have not seen similar artifacts, although I rarely find a need to sharpen my M8 files. Link to post Share on other sites More sharing options...
ianman Posted December 23, 2009 Author Share #20 Posted December 23, 2009 Are these artifact showing up in both M8 and M9 files? If the cause is something to do with the Bayer array, the size of the pixels, and the lack of an antialias filter, I would think files from both cameras would show similar features. I process my M8 files using Apple's Aperture and have not seen similar artifacts, although I rarely find a need to sharpen my M8 files. Just to be clear, I imported the photo from the card into Aperture and this is the result with the default profile. I applied no further sharpening nor made any adjustments. I imported the file into C1 5 and got to say that the result is way better than in Aperture ! It's a pity C1 doesn't have a plugin architecture (for Silver Effects). Link to post Share on other sites More sharing options...
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