Am I oversharpening
in [Digital Cameras]
|
From: Tetractys on 30 May 2005 14:21 George Preddy wrote: > In general, if you are sharpening at all then > you are oversharpening. This is an untrue statement. Sharpening is part of any proper digital workflow. Look here: http://www.luminous-landscape.com/techniques/process.shtml > Global digital sharpening tends to flatten or even > invert the 3D nature of an image, since contrast > is strengthened pixel by pixel, without regard to > subject depth or the optics at play. The picture > has to be really soft or taken OOF to get benefits > of digital sharpening above the cost watermarking > the image "from digital." Huh? For a good primer on sharpening, look here: http://www.luminous-landscape.com/tutorials/sharpness.shtml or an alternative, try this: http://www.luminous-landscape.com/tutorials/high-pass-sharpening.shtml Here is another good tutorial on USM: http://www.creativepro.com/story/feature/11242-1.html Here is MS's version of the comment that Bayer filtering is responsible for the necessity of USM in the first place: http://www.microsoft.com/windowsxp/using/digitalphotography/learnmore/sharpening.mspx
From: Stacey on 30 May 2005 14:56 Tetractys wrote: > > Here is MS's version of the comment that Bayer filtering is > responsible for the necessity of USM in the first place: > http://www.microsoft.com/windowsxp/using/digitalphotography/learnmore/sharpening.mspx Wow you stepped right into it, here's where George explains that's why Bayer filtering is such a bad thing... -- Stacey
From: Tetractys on 30 May 2005 15:32 Stacey wrote: > Wow you stepped right into it, here's where George > explains that's why Bayer filtering is such a bad thing... Not really. It's an issue that should be addressed in any discussion of Bayer filtering -- the need for post-process sharpening. You can't avoid it, and the need is there. George's problem is that he blames the Bayer filter for global problems like entropy and unrest in South- west Asia, and believes that a crappy camera based on poorly-implemented Foveon technology is superior despite overwhelming evidence and opinion to the contrary. So I'll step in it all day long, but call it what it is. Bayer = water puddle; Sigma = dog poop.
From: george_preddy on 30 May 2005 16:42 C Wright wrote: > On 5/30/05 9:16 AM, in article > 1117462598.038828.135100(a)g44g2000cwa.googlegroups.com, > "george_preddy(a)yahoo.com" <george_preddy(a)yahoo.com> wrote: > > > > > > > Celtic Boar wrote: > >> Please take a look at the attached link. I am still trying to get the hang > >> of this Unsharp Mask Thing. Are these oversharpened. > >> > >> Canon 20D - Raw - 75-300 IS Zoom > >> > >> Thanks. > > > > I couldn't find any oringals there so there is no way to evaluate the > > images for sharpness. In general, if you are sharpening at all then > > you are oversharpening. > > > > Global digital sharpening tends to flatten or even invert the 3D nature > > of an image, since contrast is strengthened pixel by pixel, without > > regard to subject depth or the optics at play. The picture has to be > > really soft or taken OOF to get benefits of digital sharpening above > > the cost watermarking the image "from digital." > > > Considering your reputation in this group There are 17 different George Preddys posting here, which one are you? > I hesitate to reply at all but for > the sake of potential newer dlsr users I can't let this statement stand! > Unless someone has optional in-camera sharpness cranked way up dlsr's are > noted for producing soft images - this is by the manufacturer's design. No, it is the Bayer design. Since all Bayer cameras (all digitals except Foveon based) output images that are already upscaled by 400%. P&S's have harsh built in digital sharpening that can't be changed. DSLRs are no softer, they stop short of oversharpening everything before you see the image. My point stands. Digital sharpening ruins images because it plows through every pixel blindly, instead of leaving sharpness/blur to optics. That is why film lovers hate digital, the result is flat and lifeless, often even inverted. If you sharpnen digitally, you are simply exceeding the capabilites of your camera at the expense of quality. The only proper way to handle digital images that are breaking down is to print them at the size they were intended. There are no acceptable algorithmic crutches that can substitute for sensor count. > Most all advanced amateurs and pros prefer it this way and will use some > sort of post processing program and either leave their images soft or > sharpen as desired. Many, many images benefit from sharpening and to say > that "In general, if you are sharpening at all then your are > oversharpening." is just plain wrong! As far as the rest of your statement > about sharpening tending to tending to "flatten" or "invert the 3D nature" > of an image - huh! If your camera needs sharpening, the only quality solution is to downsize the already upscaled image to what your camera's sensor count actually supports. Bayer images are properly viewed at their optical, not recorded, resolution. That is, 25% of the recorded size, or a complete dedicated RGB sensor triplet for every presented color pixel. If you are printing on paper, this is done for you. At smaller print dimensions the image will look very sharp due to the printer automatically cramming all of the optical data within the choosen dimensions. At the enlargement size that you notice unacceptable blur, you should stop and buy a better camera. Digital oversharpening is never a pro quality solution beyond that optical limit, though it can certainly is an oft used, low quality approach.
From: george_preddy on 30 May 2005 16:52
Tetractys wrote: > Not really. It's an issue that should be addressed > in any discussion of Bayer filtering -- the need for > post-process sharpening. You can't avoid it, and > the need is there. Of course you can avoid it. Don't output at 400% the supported optical resolution of the sensor. You need an dedicated RGB triple for every ooutput pixel or obviously you are right, the recorded image will look bad. > George's problem is that he blames the Bayer filter > for global problems like entropy and unrest in South- > west Asia, and believes that a crappy camera based > on poorly-implemented Foveon technology is superior > despite overwhelming evidence and opinion to the > contrary. Like it or not, well focused Foveon images don't need sharpening in post processing. Why? Because the images are recorded at the sensor's optical resolution--one dedicated RGB tiple for every RGB recorded pixel. Bayers record a 400% upscale by default, since most use Bayers, people are conditioned to think digital imagery always sucks. It doesn't, but it isn't magic either, you need real live RGB sensors to see then record RGB images. Not a sharpening algorithm applied long after the shutter closed. My 1DMkII, for example, is a 2MP camera. I knew that when I bought it. The camera's 8MP, 400% upscaled output will obviously look too blurry and too flat after sharpened into oblivion. How could an 8MP recording not look horrid with only 2M pixels worth of actual full color optical data? At 2MP, image quality is sharp, 3D, and life like. People simply expect too much from low MP cameras. If you digitally sharpen, you are in that group. |