Am I oversharpening
in [Digital Cameras]
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From: george_preddy on 5 Jun 2005 19:09 Bart van der Wolf wrote: > <george_preddy(a)yahoo.com> wrote in message > news:1117934606.605577.297030(a)g47g2000cwa.googlegroups.com... > SNIP > > Bayer DSLRs are characteristically blurry and soft because the true > > optical resolution is the resolution of each, individual, tiny, > > subdivided, R, G, or B exposure, [...] > > How typical, only half-truths (if any). > Did you forget about lens quality and the anti-aliasing filter, which > are the true source for blur? Resolution is limited by that, the > sampling density, and output magnification. A camera can't have an a blur filter and have high optical quality. Intentionaly introducing blur and optical quality are not compatible notions. Granted, blur is the lesser of two evils--vice having color moire rampant in any area of detail. "Lesser of two evils" is hardly an endorsement for using mosiacs to keep a camera's optics super cheap.
From: C Wright on 5 Jun 2005 20:01 On 6/5/05 2:12 PM, in article 1117998769.068229.129430(a)f14g2000cwb.googlegroups.com, "george_preddy(a)yahoo.com" <george_preddy(a)yahoo.com> wrote: > > > C Wright wrote: >> On 5/30/05 3:42 PM, in article >> 1117485741.612985.156090(a)o13g2000cwo.googlegroups.com, >> "george_preddy(a)yahoo.com" <george_preddy(a)yahoo.com> wrote: >> >> >>> >>> 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. >>> >> George (if that is your name) you are a piece of work! Any digital >> sharpening that I have done does not plow through every pixel blindly. >> Sharpening that I am familiar with is adjustable according to threshold, >> radius and degree or amount. > > That has nothing to do with lens optics that should produce blur in > some places and sharpness in others. George or Molly or whoever the hell you are, what the hell does your answer, immediately above, have to do with my response to your assertions?? You made a simplistic untrue statement about digital sharpening and I responded. Then you, in turn, reply with some blather about lens optics! The issue was digital sharpening on a computer and had absolutely nothing to do with lens optics. >> Millions of images taken by thousands of >> digital photographers, and sharpened digitally, disprove your assertion that >> they are all exceeding the capabilities of their cameras at the expense of >> quality. > > No it doesn't. Digital has a very bad reputation among no-comprimise > photographers, because the overwhelming majority of people who use > digital don't understand that their Bayers take 3 very small RGB > exposures, then combine them while upscaling by 400%. The upscaling > makes the pics blurry and flat. Artifically sharpening from top to > bottom, without regard to optics may make some of the edges arbitrarily > sharper, but flattens the overall image even more, or may even > perceptually invert parts of it. > > It is no coincidence digital is criticized by serious photographers and > clients--even if they don't understand why, they know a flat, lifeless, > low resolution image when the see it. The very few "no compromise" photographers out there who continue to choose film over digital don't use Foveon sensors either. For you to try to make that an argument against Bayers is ridiculous. Again, I stand by my statement that millions of published digital images (taken by photographers using Bayer sensors) disprove your assertion that they are all exceeding the capabilities of their cameras at the expense of quality.
From: Paul Furman on 5 Jun 2005 23:13 george_preddy(a)yahoo.com wrote: > > A camera can't have an a blur filter and have high optical quality. err uh hmm OK ??? "an a blur??? Hmmm??? So the Foveon has no antialiasing filter? A s I understand, antialiasing has nothing to do with this issue, it has to do with the resolution of the camera matching the resolution of a geotric pattern and a foveon would be just as susceptible to that effect as any 3.4MP sensor. Please clarify. > Intentionaly introducing blur and optical quality are not compatible > notions. Granted, blur is the lesser of two evils--vice having color > moire rampant in any area of detail. > > "Lesser of two evils" is hardly an endorsement for using mosiacs to > keep a camera's optics super cheap. >
From: george_preddy on 6 Jun 2005 01:12 Paul Furman wrote: > george_preddy(a)yahoo.com wrote: > > > > A camera can't have an a blur filter and have high optical quality. > > err uh hmm OK ??? > > "an a blur??? Hmmm??? > > So the Foveon has no antialiasing filter? A s I understand, antialiasing > has nothing to do with this issue, it has to do with the resolution of > the camera matching the resolution of a geotric pattern and a foveon > would be just as susceptible to that effect as any 3.4MP sensor. > > Please clarify. You understand wrong. An AA filter (a very simple blurring filter) is required by Bayers, but not by any camera with full color photosites like Foveon or 3-CCD/CMOS. Why? If you don't blur fine detail over many individual sensors with a Bayer, you'll get little rainbows in any area of fine detail because the sensors are monochrome and therfore can only sense one color per location. So any pixel-level detail appears in an essentially random color, just depending on whatever color sensor it happened to land upon. Assuming that sensor's color filter didn't block the feature entirely. The blur filter ensures that any pixel-level detail is blurred over many pixels, so the color can be better determined. The tradeoff is intentional image blur. The now out of production Kodak 14n actually blurred the fine detail with a digital blur filter instead of an optical one, interestingly. It didn't work well at all... http://img2.dpreview.com/gallery/kodakslrc_samples/originals/f6fm1074-raw-acr.jpg Because of the blur filter, one can rightly think of a Bayer sensor as a full color sensor, where each full color pixel is actually a block of 4 sensors (RGGB) with the blur filter ensuring no fine detail smaller than that total area is allowed to pass. Same thing I said earlier, the actual color resolution is advertised MPs/4.
From: george_preddy on 6 Jun 2005 01:33
Tetractys wrote: > 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 Only Bayer workflow needs artificial sharpening. That is one of several reasons why "digital" (read: Bayer) images are always paper flat. |