Maintaining image fine detail.

[Enrique Patino]

Interesting discussion.

Intuitively, from what I've read here, an iterative process with floating points seems more "powerful" or more "precise"... enough to peak my interest. The idea of merging images to apply the right tweak to sections of the image as needed is not new -just being discussed in terms of "sharpening" effects. I am setting up my laptop to run linux to try deconvolution and open source software for RAW conversion. It is worth a try.

How is the term "resolution" being used here? as the ability to resolve detail? how would you define resolution of an images of fog? Better understanding of the term resolution would help me understand this better, I think. Sorry if it was described and I missed it.

Thanks!

[Floyd Davidson]

pane 49 by HD
the 2nd, middle, image by AH is very obviously higher contrast than original or RC's. (or not?) Is higher contrast considered sharpening? What does higher contrast contribute to sharpening, if anything?
Because in RC image I see only 2 px in the eye highlight, does that mean it is the sharpest?
Tom

http://www.lensrentals.com/news/2009...en-my-acutance

The 2 pixels in the eye highlight is because Richardson-Lucy produces "oversharpening" as an artifact on an already sharp transition if the spatial frequency is high enough. The same effect is seen on thin lines (high frequency) where the result is a jagged line after sharpening. It probably also produces artifacts if another form of sharpening (either intentionally or as part of a down sampling algorithm) has produced ringing artifacts, which RL will then emphasize.

Typically other forms of sharpening leave visible ringing artifacts on the bright side of a transition, while Richardson-Lucy leaves ringing artifacts on the dark side.

That can be used either to advantage or it can be a disadvantage.

[Tom Graham]

"Typically other forms of sharpening leave visible ringing artifacts on the bright side of a transition, while Richardson-Lucy leaves ringing artifacts on the dark side."
Now that is interesting. I always looked for the increased brightness on the lighter side of the "line". But sure, why not, if bright can go brighter then dark can go darker.

Tom

[Roger Clark]

In looking at the image comparison Tom posted, I noticed something funny: the catchlight seemed offset between the two images. So I registered Arash's sharpened image with the original jpeg image and made an animated gif, attached. The original jpeg image was enlarged 2x for easier examination of the problem, and Arash's posted image registered to that enlarged original, independent of Tom's comparison.

Notice there is no shift in the image in general (e.g. beak, feathers, pupil). BUT the catchlight shifts upward in Arash's sharpened image, and by more than the radius of the catchlight. No other features shift like this. I do not know of any sharpening method that will cause such a shift, let alone any tool in Photoshop, which is what Arash says he used for the sharpening. My RL deconvolved image is well registered with the rest of the image with no shift of the catchlight, just like expected (anyone can verify that independently with the already posted images). I can't reproduce such a shift with unsharp mask or smart sharpen on Arash's original jpeg he posted. Unless it can be independently proven that a photoshop tool can cause such a shift, this is evidence for clear hand manipulation of the result: the catchlight was put in by hand to make the image look better.

Please prove me wrong and show me how this is possible. To do that, please post the image file that was used in the sharpening procedure and the detailed procedure in photoshop that will reproduce the effect such that it can be verified by independent parties.

Roger

[arash_hazeghi]

Well, Arash,

Perhaps we'll just have to agree to disagree. I do not see your image as an improvement at all. First you brightened it and that skews the visual impression. It is kind of like the stereo salesman boosting the volume on one system, to make it seem better than another when it really is not. I see in your image a lot of ringing artifacts. For example, around the beak and talons. Look at the catchlight in the eye. Your image has double the pixels making up the catchlight compared to the RL deconvolution image. If you put the two images side by side in a photo editor and enlarge to 200%, all these ringing artifacts in your image will be more easily visible.

And you did not start with the same jpeg image that you originally posted for me to work on because your reworked image above shows more vegetation in the lower right corner than the image you gave me. That is not the same file.


Roger

Are you implying that I lied and started with a different frame? Do you think I had two files with the bird exactly at the same location and same pose? Is that even possible? I find that insulting and unprofessional Roger.

As for vegetation I masked that area obviously. I don't sharpen my BG.

As for catch light, yes I did use a brush to define it better and thus the shrinking, I forgot to mention. But that does not make a difference in final output (see below).

I agree that we have to disagree, you can write a million words and bring thousands of unrelated references, but your theories do not hold water IMO. If not better my file is just as good and that's the bottom line for me and I achieve this in 30 seconds. Anyone with a healthy pair of eyes can see and decide for themselves.

Here is one with no catch light correction and no additional cropping. I actually just downloaded from my own link and worked on it from scratch. It does not change the conclusion.


Attachment 137199



I think this thread has run its course for me, I will keep the original online for a while if other folks want to work on it (only for posting on this thread, please do not print or post elsewhere). I have nothing more to add.

[arash_hazeghi]

I agree not same file. Because when I tried magnification (600%) each RC and AH jpgs in PS the bird heads are different sizes. AH's being larger. And AH bit brighter (caused by sharpening?).
Look at both images in PS at 600%. Note striking differences in contrast. Note AH eye highlight is 4px, RC is 2px. Another quite obvious difference is noise(?) in background.

To make a comparison to show here, I cropped each to a size of 144x103x around the head. 144x103 is small here so I resized each to 550px wide. Yes, resizing blurred it all some. For best comparison you magnify each 600% in PS. Anyway just to put up something like I see -
Tom (and please don't nit-pik on this image, do it correctly yourself and compare)

They are the same file. (See image in the pane #55)

size is different because I slightly re-cropped the image before posting.

Obviously, you do not sharpen the BG, I mask the BG before sharpening the bird. If you look at the vegetation they are not sharpened either.

Also, keep in mind, when in doubt it is more professional to ask someone for an explanation before saying "it is not the same file" and thus accusing them of lying.

[Don Lacy]

I would like to make a few observations and comments as a simple photographer without the advance degrees or scientific knowledge as some of the participants on this thread. First I am only interested in techniques or tools that that help me achieve my vision as an artist if something comes along that advances that agenda I will incorporate it into my workflow. With that said I was really impress with what Roger was able to do with Richardson-Lucy deconvolution to the Gaussian blurred image to my eye the image with deconvolution sharpening looked the best, but as Arash has pointed out using a Gaussian blur plays to the strength of Richardson-Lucy and tilts the playing field in that direction. So I was really interested in what Roger would be able to do with the image Arash supplied and to be honest the image to my eyes is not presentable and I am only referring to the Kite not the BG or vegetation while Roger version appears to be slightly sharper in the face and eye there is noticeable artifacts along the wing edges at normal viewing size, while Arash version is slightly better but still really not presentable as anything other then a small jpeg. Now I also believe that as Roger stated that providing an 8bit jpeg tilts the playing field in the other direction and puts him at a disadvantage. So I am providing a neutral Raw file of a soft Road Runner image I took at bosque https://www.dropbox.com/s/xhe7wfjzf0cx8fa/_52B7483.CR2 anyone is welcome to download and work on it, all I ask is that your detail your workflow from start to finish and repost the image at 1200 pixels. I am also wondering which method is better when you start with a in focus image so here is a link to another Raw file that should be a good starting point for a decent image https://www.dropbox.com/s/5ynh5p6o1bls9mv/_52B5667.CR2

[Don Lacy]

For my own amusement I downloaded the 8bit image Arash provided and came up with pretty much the same image Arash posted not as sharp but lacking some of the artifacts in his image as well, if you push the image any harder it start to fall apart.

[dankearl]

Opened in ACR, adjusted exposure and WB.
Adjusted color channels, having never see a RR, I do not really know proper color.
Saved as TIFF, opened in NR2.
Cropped, sharpened bird only with unsharp, erased a couple of dark spots along the focus line in the dirt,
Ran NR once on BG only.
Saved for web at 398kb.
This took about 2 or 3 minutes, the usual time I PP birds.
It looked good enough to me for the web and not bad at full size on my monitor.
Legs are not in focus, neck is marginal.

RRdan.jpg

[dankearl]

After looking at the photo, I opened the TIFF file again in NR2 and redid the PP, cropped a tad more, sharpened with unsharp mask more aggressively,
added some color saturation and ran NR on BG only and lightened shaded breast a tad.
Again, I removed a dark blog of the shadow in front of the feet.
Forgot to mention, I did some CCW rotation on both photos.



RRdan2.jpg

[Arthur Morris]

This is a common myth. See this excellent BPN thread (viewed 18,300 times to date):

http://www.birdphotographers.net/for...ng-Information!

So correct because Roger says so? See Don's comment below.

[Roger Clark]

Originally Posted by John Chardine

This is a common myth. See this excellent BPN thread (viewed 18,300 times to date):

http://www.birdphotographers.net/for...ng-Information!

So correct because Roger says so? See Don's comment below.

Wow.

Art, it is basic math. Any image one obtains is a convolution of the original scene. In simple terms, that is blur (e.g.from diffraction, lens aberrations) When one downsizes an image, that is another convolution with sub-sampling. The convolutions work together to make the image blurrier than the original, then the sub sampling hides some of the result.

In more familiar terms to photographers, think of MTF. MTF describes at what level the optical system can record detail. The MTF of any image recorded with an optical system is not perfect (e.g. blurred by lens aberrations and diffraction), thus less than 1. Downsampling lowers MTF. The second MTF multiplies the first MTF (any two numbers less than one multiplied together result in an even smaller number), so if you start with a low MTF image (e.g. blurred), the downsized image will be blurrier (even lower MTF) than if you started with a higher MTF image (a sharper image). I think this is proven all the time here when people complain the original image was not sharp enough. If a sharp image wasn't needed to start with, we would not hear people here saying it was close but not sharp enough so should be deleted.

Everyone can test this effect. Find two images where with one the focus is slightly off, thus slightly blurred (and lower MTF). Down sample both then sharpen the same. Can you see a difference? One can partly compensate with more sharpening on the downsampled blurier image, but usually with increased artifacts, as demonstrated in this thread, e.g. Arash's test image. However, if you sharpen first then downsample, the result is sharper (again the multiplication of the two MTFs--back to basic math). All real-world sharpening also results in artifacts. So if you sharpen first, then down sample, those artifacts are smaller by definition. Another win.

Perhaps some of the confusion lies in how often to sharpen. Any time one downsizes, sampling theory says there is degradation in MTF (the convolution). Thus after down sampling, one needs to sharpen, even if one sharpened before. The lesson is anytime there is a convolution, one can sharpen (ideally with deconvolution). When the image is obtained, that is the first convolution, so best to sharpen (deconvolve) at that point.

Regarding some other comments in this thread about not thinking my references are relevant, I gave deconvolution references ranging from astronomy to microscopy. That pretty much covers the focal length and magnification range of photography. Everything else is in between. I had hoped people would see the proverbial light: Ah Ha, if high magnification microscopy can be deconvolved and low magnification images made at infinity with long lenses can be deconvolved, I should be able to deconvolve my images too.

Roger

[Floyd Davidson]

Perhaps some of the confusion lies in how often to sharpen. Any time one downsizes, sampling theory says there is degradation in MTF (the convolution).Thus after down sampling, one needs to sharpen, even if one sharpened before. The lesson is anytime there is a convolution, one can sharpen (ideally with deconvolution). When the image is obtained, that is the first convolution, so best to sharpen (deconvolve) at that point.

Obfuscated, but there is the admission that everyone else was right in the first place. Incidentally, for most images the greater the downsize the more effective Unsharp Mask will be and the less effective either deconvolution or high pass sharpen, though that is very dependent of the type of detail in the image.

And given the somewhat equally confused previous commentary on "ringing" earlier, it suggests that Roger Clark is very good at data collection. Others are very good at explaining what the data shows or does not show.

[Enrique Patino]

I enjoy reading Roger's posts and writing...I admit, some of it is over my head. I am a biologist. But after reading a few times, I find the stuff very informative... provocative at the very least...

Maybe a little "heat" is good for these discussions, as it pushes one to defend one's views and positions... and thus these discussions can get packed with info... but these type of discussions do reveal character also... ;)

I wonder if Simon got what he needed out of this thread

[Roger Clark]

Obfuscated, but there is the admission that everyone else was right in the first place. Incidentally, for most images the greater the downsize the more effective Unsharp Mask will be and the less effective either deconvolution or high pass sharpen, though that is very dependent of the type of detail in the image.

And given the somewhat equally confused previous commentary on "ringing" earlier, it suggests that Roger Clark is very good at data collection. Others are very good at explaining what the data shows or does not show.

The myth that John referred to is that it is a myth to ONLY sharpen after downsizing, and that it is wrong to sharpen before downsizing.

Art pointed out that the thread John referred to had sharpening post downsizing as well. So the idea that one should ONLY sharpen after down sizng is the myth. To say it is incorrect to sharpen before down sizing is simply wrong. I have always had the position that one should sharpen on the high resolution image, then sharpen again after any resampling (e.g. downsizing). That is clearly stated in my response in pane 14 of the BPN thread that John referenced, and is it clear on my web site on digital work flow: http://www.clarkvision.com/articles/digitalworkflow/

Roger

[Arthur Morris]

Originally Posted by John Chardine

This is a common myth. See this excellent BPN thread (viewed 18,300 times to date):

http://www.birdphotographers.net/for...ng-Information!

Wow.

Art, it is basic math. Any image one obtains is a convolution of the original scene. In simple terms, that is blur (e.g.from diffraction, lens aberrations) When one downsizes an image, that is another convolution with sub-sampling. The convolutions work together to make the image blurrier than the original, then the sub sampling hides some of the result.

In more familiar terms to photographers, think of MTF. MTF describes at what level the optical system can record detail. The MTF of any image recorded with an optical system is not perfect (e.g. blurred by lens aberrations and diffraction), thus less than 1. Downsampling lowers MTF. The second MTF multiplies the first MTF (any two numbers less than one multiplied together result in an even smaller number), so if you start with a low MTF image (e.g. blurred), the downsized image will be blurrier (even lower MTF) than if you started with a higher MTF image (a sharper image). I think this is proven all the time here when people complain the original image was not sharp enough. If a sharp image wasn't needed to start with, we would not hear people here saying it was close but not sharp enough so should be deleted.

Everyone can test this effect. Find two images where with one the focus is slightly off, thus slightly blurred (and lower MTF). Down sample both then sharpen the same. Can you see a difference? One can partly compensate with more sharpening on the downsampled blurier image, but usually with increased artifacts, as demonstrated in this thread, e.g. Arash's test image. However, if you sharpen first then downsample, the result is sharper (again the multiplication of the two MTFs--back to basic math). All real-world sharpening also results in artifacts. So if you sharpen first, then down sample, those artifacts are smaller by definition. Another win.

Perhaps some of the confusion lies in how often to sharpen. Any time one downsizes, sampling theory says there is degradation in MTF (the convolution). Thus after down sampling, one needs to sharpen, even if one sharpened before. The lesson is anytime there is a convolution, one can sharpen (ideally with deconvolution). When the image is obtained, that is the first convolution, so best to sharpen (deconvolve) at that point.

Regarding some other comments in this thread about not thinking my references are relevant, I gave deconvolution references ranging from astronomy to microscopy. That pretty much covers the focal length and magnification range of photography. Everything else is in between. I had hoped people would see the proverbial light: Ah Ha, if high magnification microscopy can be deconvolved and low magnification images made at infinity with long lenses can be deconvolved, I should be able to deconvolve my images too.

Roger

Hi Roger,

If my comment above drew a "wow" from you I can't wait to see your response to my comments in Pane #54 here: http://www.birdphotographers.net/for...tion!?p=970277

We've been down this road before. I have 30+ years experience in nature photography, have had probably 20+ images honored in 3 of the world's most prestigious contests; my images have been published the world over. I don't know how to read an MTF chart. I don't know what convolution is. have no clue what high magnification microscopy is. Has that hurt me or my success?

In my new comment linked to above I quote respected Digital Guru Tim Grey who disagrees completely with your premise and your initial response to my comments that images should be sharpened after being sized for final usage.

Respectfully.

[Arthur Morris]

The myth that John referred to is that it is a myth to ONLY sharpen after downsizing, and that it is wrong to sharpen before downsizing.

Art pointed out that the thread John referred to had sharpening post downsizing as well. So the idea that one should ONLY sharpen after down sizng is the myth. To say it is incorrect to sharpen before down sizing is simply wrong. I have always had the position that one should sharpen on the high resolution image, then sharpen again after any resampling (e.g. downsizing). That is clearly stated in my response in pane 14 of the BPN thread that John referenced, and is it clear on my web site on digital work flow: http://www.clarkvision.com/articles/digitalworkflow/

Roger

Aside from very small amounts of in-camera sharpening I believe that it is wrong to sharpen your master files so that they are sharp enough to print from. And the vast majority of digital photography and print experts preach and teach the same thing.

[Floyd Davidson]

The myth that John referred to is that it is a myth to ONLY sharpen after downsizing, and that it is wrong to sharpen before downsizing.

False.

John very clearly was responding only to DickLudwig's comment that the final sharpening (not all sharpening) should be done after downsizing Claims that such advice is a myth are patently incorrect. So are suggestions that anyone is saying no sharpening should happen before the ultimate resampling. In fact any "local" sharpening is typically done to an image at the original size. The point is and always has been that resampling is itself a cause for appropriate sharpening that cannot be done prior to resampling.

And of course if the resampling causes a significant reduction in size, it is generally true that USM will be more effective than other tools.

Here is the entire article by John, positively identifying which of your myths he referenced:

If you downsize an image you should do the final sharpening after you do the downsize, not before.

This is a common myth. See this excellent BPN thread (viewed 18,300 times to date):

http://www.birdphotographers.net/for...ng-Information!

And I'll repeat my initial remark about that article: Not a myth at all, but the cited thread is loaded with inaccuracies.

[Gary Kinard]

I enjoy reading Roger's posts and writing...I admit, some of it is over my head. I am a biologist. But after reading a few times, I find the stuff very informative... provocative at the very least...

Maybe a little "heat" is good for these discussions, as it pushes one to defend one's views and positions... and thus these discussions can get packed with info... but these type of discussions do reveal character also... ;)

I wonder if Simon got what he needed out of this thread

+1

I've bought equipment, based on what Rodger said, always spot on.
For technical information his site is the place to go. Hands down IMO.


www.birdsthatfart.com
www.flickr.com/photos/avianphotos

[Diane Miller]

Things seem to be getting mired here. Let me propose (for those of us whose doctorates are not in such extraordinarily technical fields) an attempt at a summary. I hope the principals here will comment on it. I really don't care who said what, but surely there is a "most reasonable" solution for those of us who wish to maintain image detail.

1) The digital capture process (lenses and all that) and the process of turning a digital capture into an image file (demosaicing and all that) results in a softer image than is ideal.

2) Some CAREFUL sharpening can and should be done in a RAW converter to mitigate those effects, and can, if done carefully, be done without causing significantly damaging artifacts to the file. In recognition of this, ACR and LR have a modest default sharpening amount, which is done to the L channel of the image, which is handled behind the scenes in LAB mode. That sharpness will, of course, be contained in the rasterized TIFF or PSD master file, which should always remain at its native size. (How to find that ideal sharpness point is another topic, and will undoubtedly vary somewhat from image to image.)

3) When a DERIVATIVE image is resized for printing or web output (larger or smaller) some sharpness will be lost and it should be sharpened again.

The various sharpening methods aside (for now), isn't it this simple?

[Doug Brown]

Things seem to be getting mired here. Let me propose (for those of us whose doctorates are not in such extraordinarily technical fields) an attempt at a summary. I hope the principals here will comment on it. I really don't care who said what, but surely there is a "most reasonable" solution for those of us who wish to maintain image detail.

1) The digital capture process (lenses and all that) and the process of turning a digital capture into an image file (demosaicing and all that) results in a softer image than is ideal.

2) Some CAREFUL sharpening can and should be done in a RAW converter to mitigate those effects, and can, if done carefully, be done without causing significantly damaging artifacts to the file. In recognition of this, ACR and LR have a modest default sharpening amount, which is done to the L channel of the image, which is handled behind the scenes in LAB mode. That sharpness will, of course, be contained in the rasterized TIFF or PSD master file, which should always remain at its native size. (How to find that ideal sharpness point is another topic, and will undoubtedly vary somewhat from image to image.)

3) When a DERIVATIVE image is resized for printing or web output (larger or smaller) some sharpness will be lost and it should be sharpened again.

The various sharpening methods aside (for now), isn't it this simple?

It's that simple Diane!

[Floyd Davidson]

Things seem to be getting mired here. Let me propose (for those of us whose doctorates are not in such extraordinarily technical fields) an attempt at a summary. I hope the principals here will comment on it. I really don't care who said what, but surely there is a "most reasonable" solution for those of us who wish to maintain image detail.

1) The digital capture process (lenses and all that) and the process of turning a digital capture into an image file (demosaicing and all that) results in a softer image than is ideal.

2) Some CAREFUL sharpening can and should be done in a RAW converter to mitigate those effects, and can, if done carefully, be done without causing significantly damaging artifacts to the file. In recognition of this, ACR and LR have a modest default sharpening amount, which is done to the L channel of the image, which is handled behind the scenes in LAB mode. That sharpness will, of course, be contained in the rasterized TIFF or PSD master file, which should always remain at its native size. (How to find that ideal sharpness point is another topic, and will undoubtedly vary somewhat from image to image.)

3) When a DERIVATIVE image is resized for printing or web output (larger or smaller) some sharpness will be lost and it should be sharpened again.

The various sharpening methods aside (for now), isn't it this simple?

With the exeption of the two words I've made bold, your statement is indeed very good, and about as simply stated as can be.

There is no technical need for capture sharpening:

1. If capture sharpening is used, it can be done either as part of RAW conversion or later in a separate editor.
2. Rather than capture sharpening, one might consider "local sharpening" of only the specific areas of an image where it is useful,
3. note that some areas many need "local blurring", in which case capture sharpening is counter productive and not recommended.

[Roger Clark]

What personal attacks are you referring to Roger? Please indicate with Pane #s. Thanks.

ps: Aside from very small amounts of in-camera sharpening I believe that it is wrong to sharpen your master files so that they are sharp enough to print from. And the vast majority of digital photography and print experts preach and teach the same thing.

Art, there have been numerous posts in this thread that have been deleted because they were personal attacks.

I find your statement "So correct because Roger says so?" interesting and then you call my responses scientific mumbo jumbo in the post your referenced. Then you cite Tim Grey because he says so. You take Tim's word solely based solely on his expertise. Many times experts have been wrong. I have been wrong. What counts is mathematical and scientific correctness if one is going to say it should be only one way, and that should be demonstrable. And if it can be demonstrated, then it shouldn't matter either way, Tim saying one can sharpen a little before downsizing, but what is a little? What is the reason why? If that is really the correct way, there should be a solid mathematical argument. It should be obvious in a test why it fails. To simply cite experts is not sufficient and would not work in any scientific journal. It shouldn't be here either because we should be teaching people new things. If BPN is to teach others good ways, shouldn't they be equally explored? If you really want to cite a persons expertise, I was writing imaging processing algorithms long before photoshop, and I have invented and published new image processing algorithms and used them to make new discoveries. But it is irrelevant to the correct argument for or against sharpening at various steps. And if two experts disagree, why not simple explore the two methods and see if there really is a difference? How about demonstrating how it is bad, rather than just declaring it? I proposed tests. Has anyone tried it?

Diane, your point #2, regarding careful sharpening. What is careful, what is modest? Personally, I find making the sharpest image possible from the data works very well, and downsizing for any other size has not only no bad side effects, but produces a sharper image after downsizing so needs less sharpening after downsizing. And the math says that is the way it should be (that starting with a sharper image results in a sharper image after downsizing).

Perhaps why people have come to a different conclusion may be because they produced too many sharpening artifacts on the high resolution image which propagates into the down sized image. That might be a common problem with only using unsharp mask. But if one sharpens and controls artifacts well, it does not degrade the down sized image. So maybe the answer to my above questions is simply sharpen the full resolution image some but not enough to cause artifacts that are large enough to propagate into the downsized image. This is just a working theory that needs to be tested.

Roger

[Floyd Davidson]

I find your statement "So correct because Roger says so?" interesting and then you call my responses scientific mumbo jumbo in the post your referenced. Then you cite Tim Grey because he says so. You take Tim's word solely based solely on his expertise.

Better understanding the logic used would help. A valid Argumentum Ad Verecundiam requires at least three standards be met. 1) The authority must have expertise about the subject matter (e.g., as opposed to actually being an authority in another field). 2) The stated opinion by the authority must be in basic agreement with the other experts in that field. 3) The stated opinion must be serious (as opposed to a joke or ill worded offhand comment not meant to be taken seriously).

I would suggest that Roger Clark is not an authority on image sharpening, and regardless it is very clear that his opinion on this topic is not in agreement with most recognized authorities. Many sources cite a 4th standard, a lack of bias, which Roger also fails in this example. Therefore an appeal to authority citing Roger Clark's opinion is not valid logic.

Tom Grey is a recognized authority. His statements about image sharpening are both in agreement with other recognized authorities and are in fact also cited by them. Therefore an argument citing Tom Grey's opinion is a valid appeal to authority.

As noted, Roger Clark is very good at collecting data about photographic topics. Everyone should pay attention to his entertaining articles with advice about what the data is, and should then find an expert to explain what the data means if it is complex or controversial.

[adrian dancy]

Floyd,

Can you please state with particularity why it is that you think Roger is biased.

Is it your case that Tom Grey is unbiased despite his being (as it seems to me) associated with a well known imaging company?

The assertion that Tom Grey holds an opinion that is in agreement with other authorities is the 'band wagon' fallacy.

I'm confused,Tom and others have stated that they will perform sharpening tasks on the master file!

You seem prepared to take sides against Roger and have tried to lessen his credibility as an expert. Yet, you have not attempted to point out, for instance, that Arthur Morris's comment regarding his success as a photographer (which is not disputed and indeed deserved) is not relevant to the discussion, yet may by the fact of who he is may have some level of persuasive effect. It would seem you may be biased.

Roger has not just uttered scientific 'mumbo jumbo' but used a real world bird image of a Crane's head which anyone can view and make their own mind up with, without having to understand any of the maths or what ever. Not only did Roger provide his own proof but he was prepared to put his expertise to the test by processing an image that was provided by Arash. Roger did not seek to optimise the image in any way other than use his sharpening processes. Arash unfortunately did not work on the same image dimensions and optimised his image with NR and the placement of highlight in a place where it did not belong, thus denying readers the opportunity to make an objective assessment.

Roger has been attacked in a most unprofessional way (which I may comment on later since I do not have time to deal with here).

You might wonder why am I writing here. I am not taking sides, I can assure you. The reason I'm here is because I am interested in the truth...the facts. I'm just an ordinary punter who might actually make a decision with my limited funds based on the outcome of this thread. If Roger is deemed by the the authorities as being a loose cannon and wrong then let them prove he is wrong. After all there are enough of you, and so far I regret to say those opposing Roger have put up a pretty poor show.

Kind regards

Adrian

[Diane Miller]

I'm in the same boat as Adrian here. I'd like to learn how to handle my images in the best possible way, and the personal attacks here are not helping that. My training as a scientist taught me to respect attacking facts and methods, not personalities. And it also taught me to judge conclusions (which can involve opinions) based IN PART on the experience and credentials of the person offering them. (Floyd said a similar thing in Pane 74, his first point.)

To that end I have some idea of Roger's credentials and publications, but I'm not acquainted with Floyd. If I may ask, in the interest of expanding my knowledge, can you introduce yourself to us?

And Tim Grey, while a recognized educator, has no credentials to my knowledge that make him a recognized expert in any scientific or technical field. I assume he is in contact with a number of people who are, but the things he writes and teaches are geared to a general workshop audience of extremely non-technical people. I assume that many of his opinions are (rightly) geared to a lowest common denominator. If he advises sharpening images at a certain stage, no matter how carefully he couches the recommendation, he will get a few people who will go too far and damage the image, or who will do it at the wrong stage, or anything else they can find to do wrong. So I assume he is (rightly) very conservative in what he recommends.

The discussion here is aimed at a more technical audience who can (or should be willing to) take responsibility for handling their files carefully in the interest of getting the best results, so I think it might go beyond a blanket statement of "Tim said...."

But I'm not even sure, from the last few posts above, WHAT Tim said. I'm not sure if he has or has not recommended sharpening on the master file. I've followed his daily email questions for years and I think I recall that he has mentioned that he has no objection to the default "gentle" sharpening in LR / ACR.
But I also think the controversy here goes beyond that stage, to what one does in PS prior to downsizing for the web.

I believe Roger says he approves of the default sharpening in LR / ACR and would in fact go beyond it (in PS??) for a file to be reduced to a small JPEG. I assume that would only be on a derivative file, but would occur before downsizing.

And I believe Floyd is saying this "pre-sharpening" is not necessary as it makes no difference in the final results.

And since there are different ways to "sharpen" I assume including the method(s) used is also an important part of the recommendation.

Just looking for the next "sort" here.....

[arash_hazeghi]

Floyd,



Roger has not just uttered scientific 'mumbo jumbo' but used a real world bird image of a Crane's head which anyone can view and make their own mind up with, without having to understand any of the maths or what ever. Not only did Roger provide his own proof but he was prepared to put his expertise to the test by processing an image that was provided by Arash. Roger did not seek to optimise the image in any way other than use his sharpening processes. Arash unfortunately did not work on the same image dimensions and optimised his image with NR and the placement of highlight in a place where it did not belong, thus denying readers the opportunity to make an objective assessment.


Adrian

That is False. Did you see the image in pane #55 and #58 and read my comments ? What do you mean by I did not work on the "same dimension image"? I worked on the image I provided in the link, Don started with the same image and got the pretty much the same results as I did #58). Did you not see that or what?

I think you are the one who cannot see the facts and is biased, not Floyd.

"Yet, you have not attempted to point out, for instance, that Arthur Morris's comment regarding his success as a photographer (which is not disputed and indeed deserved) is not relevant to the discussion, yet may by the fact of who he is may have some level of persuasive effect. It would seem you may be biased."

When someone is successful they must doing be something right, I find it relevant.

"You might wonder why am I writing here. I am not taking sides, I can assure you. The reason I'm here is because I am interested in the truth..."

I don't think so.

[Barry Ekstrand]

I have followed this thread with interest, as well as some prior threads in the Science of Photography section, and have come to a conclusion: BPN is not a forum for healthy, respectful debate.

I am honestly shocked and appalled at the lack of respect directed at Roger Clark in a number of the posts. It is one thing to disagree with someone, quite something else to make the kind of comments I am reading. I appreciate that Roger gives a lot of reference citations when he explains. I note that few of the contrary postings offer other references, they just disagree and disrespect. It is shameful, and it is not what I know as debate in technical societies.

In the end it seems to me that those who disagree with Roger on the sharpening stuff are really saying they believe another technique or work flow results in images that look as good or better to them. If that is right, it would be pretty simple to just say that rather than posting comments that indeed do come across as personal attacks.

I envy the skill and knowledge that the folks on BPN have with the camera and image post processing, and I can only hope to ever come near that level myself. I want to learn and continue to learn from all of you. But I think these discussions should be approached with a higher level of regard and respect for others, whether we agree with them or not.

Just my 2 cents.

Barry