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Author Topic: Canon 5D dynamic range tests  (Read 22663 times)

Ray

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« Reply #40 on: December 16, 2007, 02:37:50 pm »

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I guess the short version of all of this is this: how much dynamic range can a camera capture at its full resolution? Below a certain threshold, noise does not significantly affect resolution; the limiting factors are things like AA filter strength, lens quality, and pixel count. But once noise reaches that threshold, it begins to become the primary limiter of resolution, and every stop noise increases above that threshold halves linear resolution. What I'm trying to determine with my testing methodology is usable DR at the threshold where the noise level is just barely starting to limit overall resolution.
[a href=\"index.php?act=findpost&pid=161026\"][{POST_SNAPBACK}][/a]

I understand all your arguments, Jonathan. I understand that downsampling results in less resolution and detail.

The essense of this discussion for me can be encapsulated by just one question (of two parts).

Is the dynamic range of a camera determined only by the DR of a single pixel of average specification, or does the total number of pixels on the sensor, of that same specification, have some bearing on the matter?

If it is true that there is no dynamic range advantage in having a greater number of pixels, as you maintain, then it should not be necessary to specify the pixel width of the inner square of your target, which does after all make the testing procedures more complicated. We have to measure the width of that square and do a calculation based on the total number of pixels on our sensor (in one dimension) in order to determine how far we should be from the target.

Simply framing the entire target to cover the entire width of the sensor, as I have done, is much easier. If anyone wants to compare my results with their own results using a different camera with a different pixel count, a different pixel density and perhaps a different format, what's the problem?

They can simply downsample my file to the same size as their own, or downsample their file to the same size as mine if their's is larger, provided they have also used the simpler method of fitting the whole target to the sensor width.

Since pixel count has no bearing on the matter, according to you, where's the flaw in that methodology?

If on the other hand, pixel count does have a bearing on the DR results, then this method that I am recommending will reveal such differences.

Your method will not.
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John Sheehy

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« Reply #41 on: December 16, 2007, 02:58:59 pm »

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I can think of some models of digicam that were replaced by a higher pixel count model and the new model performed worse than the old one overall because noise levels went up so much...
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I've never seen that.  Not in the RAW data, anyway, which is all that really matters if we're talking about capture potential.  I'm sure there may be cases where overall noise increased significanty, but it wasn't because the pixels were more and smaller, per se.  It was probably because some quick and dirty readout speed was designed, or no one bothered with good microlenses on that model, or the NR just got more obnoxious.

There are many illusions that suggest deterioration of image quality with more and smaller pixels:

There is a noise-reduction race paralleling the megapixel race.

100% views get noisier.

Most downsizing algorithms used in viewers carry over individual original-pixel noise, by using nearest neighbor or a hybrid thereof.

Expectations of IQ rise.  How many great photos (IQ-wise) do you see in the 3, 4 megapixel P&S cameras of yesteryear?  Everyone talks about how much less noisy they were, yet when you go back and look at them,  they look relatively sickly, compared to today's P&S cameras that do RAW, with all kinds of bizarre detail-killing artifacts.
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Jonathan Wienke

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« Reply #42 on: December 16, 2007, 03:50:20 pm »

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Is the dynamic range of a camera determined only by the DR of a single pixel of average specification, or does the total number of pixels on the sensor, of that same specification, have some bearing on the matter?

If it is true that there is no dynamic range advantage in having a greater number of pixels, as you maintain, then it should not be necessary to specify the pixel width of the inner square of your target, which does after all make the testing procedures more complicated. We have to measure the width of that square and do a calculation based on the total number of pixels on our sensor (in one dimension) in order to determine how far we should be from the target.

Simply framing the entire target to cover the entire width of the sensor, as I have done, is much easier. If anyone wants to compare my results with their own results using a different camera with a different pixel count, a different pixel density and perhaps a different format, what's the problem?

They can simply downsample my file to the same size as their own, or downsample their file to the same size as mine if their's is larger, provided they have also used the simpler method of fitting the whole target to the sensor width.

Since pixel count has no bearing on the matter, according to you, where's the flaw in that methodology?

The problem with your method is that you're measuring DR with resolution effectively reduced to <1/2 megapixel when you fill the frame with the chart, regardless of how you upsize or downsize it after the fact. Download this ZIP file and look at the images in it and you'll see what I mean. The ZIP contains 4 image files: the the center square sized 50 pixels with 0% noise added, the center square sized 100 pixels with 2% noise, the center square sized 200 pixels with 4% noise, and the center square sized 400 pixels with 8% noise. All four images have the same amount of real resolution and detail, and are pretty much identical if you size them to equal pixel dimensions.

If you do a DR test your way with a Phase One P45+ MFDB, you're measuring the DR you can get when you've thrown away approximately 79 in 80 of your original pixels. And unless you only ever use your back to make web JPEGS, the DR measurement you'll get by doing so will be at least 3 stops greater than the DR you'll get in actual full-resolution images. Conducting the test my way will measure the DR you can achieve without throwing away most of your resolution. If you're ever going to print large enough that you send a full-resolution or upsampled file to the printer, then my method (framing to size the center square 100 pixels) is the only one that is going to deliver realistic results.
« Last Edit: December 16, 2007, 04:17:01 pm by Jonathan Wienke »
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Ray

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« Reply #43 on: December 16, 2007, 05:16:09 pm »

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If you do a DR test your way with a Phase One P45+ MFDB, you're measuring the DR you can get when you've thrown away approximately 79 in 80 of your original pixels. And unless you only ever use your back to make web JPEGS, the DR measurement you'll get by doing so will be at least 3 stops greater than the DR you'll get in actual full-resolution images. Conducting the test my way will measure the DR you can achieve without throwing away most of your resolution. If you're ever going to print large enough that you send a full-resolution or upsampled file to the printer, then my method (framing to size the center square 100 pixels) is the only one that is going to deliver realistic results.
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I don't have to throw away resolution. If you think this is not a good idea, we could uprez the smaller file to the same size as the larger file before comparing DR.

In fact, this is probably the more realistic method. I find I am often uprezzing 5D or 20D files beyond their native size/resolution at 240ppi, in order to make larger prints.

Since larger prints are usually viewed from a greater distance, I'm quite relaxed about this approach.
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Jonathan Wienke

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« Reply #44 on: December 16, 2007, 05:41:04 pm »

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I don't have to throw away resolution. If you think this is not a good idea, we could uprez the smaller file to the same size as the larger file before comparing DR.

Bullshit. Look at the ZIP file I posted. Up or downsampling the image files after the shot is taken is meaningless. When you let noise rise to the point where the smallest text is poorly legible (as shown in the example images in the ZIP), the effective resolution of the four quadrants is about 400x400 pixels total, no matter how many original pixels are in the image. All 4 images in the ZIP are equally legible and all 4 images have the same resolution. The increased noise level cancels out any resolution advantage of the images with greater pixel counts.

Go back to the full-frame test shots you've already taken, and find the one that most closely matches the legibility of my 4 example images. Now crop to the edges of the chart as closely as you can, and downsize that crop using Bicubic to match each of my test images. You'll find that you can go all the way down to 400x500 pixels without decreasing the overall detail of the image or the legibility of the text any further. Why? The crop never had more than 400x500 pixels worth of detail in the first place, because the noise level had already obliterated most of the detail in the original image.

If you shoot my target full-frame with any 3:2 aspect-ratio camera and measure DR based on the legibility of the smallest text, the only way you can get that DR in real-life images is to downsize them to 400x600 pixels before doing any cropping.

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In fact, this is probably the more realistic method. I find I am often uprezzing 5D or 20D files beyond their native size/resolution at 240ppi, in order to make larger prints.

In fact it makes your method totally invalid. Your upsized prints will have at least 2-3 stops less DR than your test will predict.
« Last Edit: December 16, 2007, 05:51:27 pm by Jonathan Wienke »
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John Sheehy

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« Reply #45 on: December 16, 2007, 06:05:00 pm »

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Here's the fallacy in your arguments: any technique you use to give the higher-resolution camera a DR advantage over the other camera (or the larger format of film) will negate the resolution advantage by a corresponding amount, and require additional exposure to boot. Yes, you can bin 4 pixels together to reduce noise levels, but then you lose the resolution gain, and still have to increase exposure by a factor of 4.[{POST_SNAPBACK}][/a]

But that's another fallacy.  You don't have to bin.  I can't speak for others, but when I use binning as a reference, it is only to show that the fine, high-res capture contains what a lower-res would, IQ-wise.  That's just a half-victory to my full argument, which is that the image is better without binning at all.  The only time binning is better, IQ-wise (storage/transmission concerns aside) is when the highest subject frequency recorded is well below the nyquist, in which case no resolution losses are concerned.  Did you do the experiment I suggested?  Here's an composite image to help you along.  This is a 100% crop of the green channel of Ray's under-exposure of your chart, and then 2x2, 3x3, and 4x4 binnings.  Look at them from up close, and at a distance.  There is no practical noise or DR benefit to the binning.  Cut and paste the image into photoshop, and make a little rectangle outside the numbers, and look at the standard deviation in the histogram.  Then, move the rectangle to the other quarters of the image.  You can see that the standard deviation changes drastically from quarter to quarter, but the practical noise and DR doesn't change.  The level of noise here obscures fine detail, but in a well-exposed area, again, the noise would be *practically* the same throughout the image, but resolution would be lost to the big pixels.

[a href=\"http://www.pbase.com/jps_photo/image/90404705/original]http://www.pbase.com/jps_photo/image/90404705/original[/url]

I've said it before, and I'll say it again; big pixel IQ is a big lie.

Big pixels only increase IQ when you increase the sensor size, too, and collect a proportionate amount of photons.  Unfortunately, read noise does not decrease at a per-pixel level as well as shot noise does, with current technology.  Real world cameras doing what my bins did would actually have more read noise.
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Jonathan Wienke

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« Reply #46 on: December 16, 2007, 06:10:32 pm »

You have some noise patterns, but no detail. What resizing did you use, nearest neighbor? Look at my images in the ZIP file, and explain to me which one has better resolution of the text in the quadrants. Show your work.
« Last Edit: December 16, 2007, 06:29:27 pm by Jonathan Wienke »
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John Sheehy

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« Reply #47 on: December 16, 2007, 06:40:49 pm »

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You have some noise patterns, but no detail. What resizing did you use, nearest neighbor? Look at my images in the ZIP file, and explain to me which one has better resolution of the text in the quadrants. Show your work.
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You don't see the numbers 0 through 6, when standing 10 feet back from the monitor?  Strange; I can see them fairly clear.  The vertical banding messes up the 3 quite a bit (I removed the horizontal banding to some degree; if the target had been shot against a black background with black borders on all sides, I could have removed more banding, both vertical and horizontal).

I pixelated, which is the same thing as binning except that it does not extend the bit depth.  There are only 8 meaningful levels in the image, though, from the original RAW, so that should not be an issue here.  I've done stuff like this promoted to 16-bit, and didn't see any difference.  The only reason that there are more than 8 values in the histogram of the non-pixelated version is that I subtracted the mean of each horizontal line from it after stretching the 8 RAW levels to 255, to reduce the banding, something that only works when the area's detail is small compared to the dynamics of the noise.

I just downloaded your Zip, and can't make any sense out of it.  You have one JPEG 400*500 with no noise, and 3 at 800*1000 with different amounts of noise, with the same FOV in each.  Yes, the ones you added more noise to have more noise, as expected, but what is your point?

Your text saying that the three images with noise added have the center square at different pixel sizes contradicts the actual pixel dimensions.
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Jonathan Wienke

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« Reply #48 on: December 16, 2007, 07:56:06 pm »

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I just downloaded your Zip, and can't make any sense out of it.  You have one JPEG 400*500 with no noise, and 3 at 800*1000 with different amounts of noise, with the same FOV in each.  Yes, the ones you added more noise to have more noise, as expected, but what is your point?

Your text saying that the three images with noise added have the center square at different pixel sizes contradicts the actual pixel dimensions.

My error, I accidentally uploaded a version of the ZIP with the wrong files in it. Try downloading again, please.

My point is that no matter what the pixel dimensions of the original capture, that if you use the illegibility of the smallest text as your baseline for defining the noise floor when running the DR test I propose, the noise level will be so high that the effective resolution of the capture area occupied by the chart will be reduced to about 400x500 pixels (high contrast black/white edges excepted). So if you fill the frame with the chart as Ray suggests, then the DR measurement you get from the procedure will only be achievable in practice for low-contrast image detail if you downsize the full frame to approximately 400 pixels in the narrow dimension. If you do not do so, then the measured DR will be 2-3 stops greater than that achievable in real-world images.

OTOH, if one conducts the test with the center white square 100 pixels wide in the original capture as I propose, then the measured DR will more accurately reflect what is achievable during the course of normal and customary photographic practice. If you measure 7 stops of usable DR using my method, then you can be confident that your camera will capture detail in a window curtain and a cabinet door that meter 7 stops apart if exposure is set properly. Ray's method might measure 9-10 stops of DR with the same camera, and cause disappointment when the camera fails to hold detail in two objects that meter 9 or 10 stops apart. The point of my procedure is to measure DR in a way that matches real-world experience, so that if you measure 8 stops of DR, that you can simultaneously hold detail in two parts of a single exposure thet meter 8 stops apart from each other.
« Last Edit: December 16, 2007, 07:59:44 pm by Jonathan Wienke »
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John Sheehy

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« Reply #49 on: December 18, 2007, 08:48:12 am »

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My error, I accidentally uploaded a version of the ZIP with the wrong files in it. Try downloading again, please.

My point is that no matter what the pixel dimensions of the original capture, that if you use the illegibility of the smallest text as your baseline for defining the noise floor when running the DR test I propose, the noise level will be so high that the effective resolution of the capture area occupied by the chart will be reduced to about 400x500 pixels (high contrast black/white edges excepted). So if you fill the frame with the chart as Ray suggests, then the DR measurement you get from the procedure will only be achievable in practice for low-contrast image detail if you downsize the full frame to approximately 400 pixels in the narrow dimension. If you do not do so, then the measured DR will be 2-3 stops greater than that achievable in real-world images.

No matter how you slice it, you are concerning yourself with the DR of the pixels, and ignoring the DR of the image.  They are both interesting, and the the latter is the most important, I think, for most photography, especially when you consider the fact that more pixels is always better, pixel DR being equal.

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OTOH, if one conducts the test with the center white square 100 pixels wide in the original capture as I propose, then the measured DR will more accurately reflect what is achievable during the course of normal and customary photographic practice. If you measure 7 stops of usable DR using my method, then you can be confident that your camera will capture detail in a window curtain and a cabinet door that meter 7 stops apart if exposure is set properly. Ray's method might measure 9-10 stops of DR with the same camera, and cause disappointment when the camera fails to hold detail in two objects that meter 9 or 10 stops apart. The point of my procedure is to measure DR in a way that matches real-world experience, so that if you measure 8 stops of DR, that you can simultaneously hold detail in two parts of a single exposure thet meter 8 stops apart from each other.
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But looking at the DR of the pixels is not how to do that.  Carry your thinking over to film, and you would be testing the DR of two different sizes of the same film with the same area of film covering the chart; only the optics would differ, and none of the benefits of the larger film would be realized.  Also, if you were comparing two films of the same format, but of different grain sizes, your method would require using different distancews or lenses to make the grain size proportional to the chart size in both cases.

The real world of photography is about the image, not individual pixels.  Individual pixel quality is only one factor in the image quality.
« Last Edit: December 18, 2007, 08:55:35 am by John Sheehy »
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Jonathan Wienke

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« Reply #50 on: December 18, 2007, 10:52:45 am »

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No matter how you slice it, you are concerning yourself with the DR of the pixels, and ignoring the DR of the image.  They are both interesting, and the the latter is the most important, I think, for most photography, especially when you consider the fact that more pixels is always better, pixel DR being equal.

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The real world of photography is about the image, not individual pixels. Individual pixel quality is only one factor in the image quality.

But individual pixel quality is being completely ignored with your methodology.

(Image quality) = (pixel quality) * (pixel quantity).

When noise levels become high enough that an individual pixel no longer contains meaningful image detail and you have to start averaging or binning them together to see the actual image data under the noise, pixel quality has been flushed down the toilet. Ignoring the effect of noise on individual pixels and looking only at the entire image is exactly the current flawed methodology that predicts grossly optimistic DR figures that are not achievable in real-world photography. In the real world, noise levels are deemed unacceptable when noise levels start causing a deterioration of resolution in low contrast subject matter such as the texture of cloth, hair, and skin, or the woodgrain pattern in furniture, etc.

The exposure range in which such subtleties can still be successfully resolved is of far more practical value to the photographer than the exposure range in which a few large, high-contrast objects can still be picked out from the background noise. My approach measures the former, yours only the latter. My approach has far more real-world relevance than yours.

If you want to dispute this, try the following experiment: Conduct the test twice, the first time with the chart filling the frame, and the second time with the chart farther away so that the white square is 100 pixels across. During both tests, have something with fine detail in the frame other than the chart, such as a doll, potted plant, or whatever, so that you have some kind of quasi-real-life subject matter in-frame besides the chart. Post the frames from both tests where the smallest chart text legibility most closely matches the sample images in the ZIP file. Looking at the doll or whatever you put in the frame besides the chart, which image has a noise level you would consider acceptable to deliver to a paying client? Post 100% crops of both the chart and the doll or whatever, or better yet, DNGs.

I look forward to seeing the results with great interest.
« Last Edit: December 18, 2007, 11:09:49 am by Jonathan Wienke »
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John Sheehy

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« Reply #51 on: December 19, 2007, 07:22:53 pm »

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But individual pixel quality is being completely ignored with your methodology.

Just to get things straight, I do not believe that it's not useful to measure pixel performance.  I am merely stating that the DR of the pixel is not the DR of the camera.  It is only the DR of the pixel.  Both should be measured.  However, in your comments there is an implication that individual pixel noise limits the DR of the camera.  It clearly does not.  If it did, a camera with 12 pixels would have the same DR as a camera with 12 billion pixels, all with the same shot noise and read noise.

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(Image quality) = (pixel quality) * (pixel quantity).

The square root of pixel quantity.

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When noise levels become high enough that an individual pixel no longer contains meaningful image detail and you have to start averaging or binning them together to see the actual image data under the noise, pixel quality has been flushed down the toilet.

Nope.  Your dismissive terminology does not render the pixels useless.  There is no threshold upon which a pixel becomes totally useless.  You simply need more of them, and you do get sufficiently more of them if you've been subdividing into smaller pixels.

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Ignoring the effect of noise on individual pixels and looking only at the entire image is exactly the current flawed methodology that predicts grossly optimistic DR figures that are not achievable in real-world photography.

No.  That's another problem, entirely.  The bigger problem is that no one has bothered to come up with a standard way of dealing with resolution vs noise, because most of the more scientifically-oriented people are missing the forest for the trees and measuring pixels, while the people looking at "images" aren't even accounting for RAW conversion issues.  Both are barking up the wrong tree.

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In the real world, noise levels are deemed unacceptable when noise levels start causing a deterioration of resolution in low contrast subject matter such as the texture of cloth, hair, and skin, or the woodgrain pattern in furniture, etc.

People are not very clever in the real world.  They get fooled very easily.

The real fact of the real world is that noise does not limit resolution any worse than having big pixels does, so the effect is moot.  Smaller pixels do, however, allow higher resolution for high contrast or tonal ranges where noise is not a big problem.

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The exposure range in which such subtleties can still be successfully resolved is of far more practical value to the photographer than the exposure range in which a few large, high-contrast objects can still be picked out from the background noise.

Most of the time, yes, but the principles are similar.  You do not get better resolution by trading for bigger pixels with less pixel noise.  It does not happen.  In less (image-)noisy tonal ranges, however, the higher resolution of the smaller pixels will resolve more detail.

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My approach measures the former, yours only the latter. My approach has far more real-world relevance than yours.

Really?  Let's take your approach to the extreme.  Let's say you use a camera that only has enough pixels to make the white square 100 pixels, when the target fills the entire frame.  You also have a camera with pixels the same size, pitch, QE, capacity, and read noise, but 100x as many of them, and shoot the target with the center crop.  What have you just tested?  You have just tested the pixels, which are exactly the same.  To say that both have the same dynamic range, as cameras, is ridiculous, because with the proper lenses for equal FOV, the camera with 100x as many pixels will show details much farther down into the shadows.

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If you want to dispute this,

I'm not sure your "this" refers to anything I actually believe, but I'll try to follow along.

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try the following experiment: Conduct the test twice, the first time with the chart filling the frame, and the second time with the chart farther away so that the white square is 100 pixels across. During both tests, have something with fine detail in the frame other than the chart, such as a doll, potted plant, or whatever, so that you have some kind of quasi-real-life subject matter in-frame besides the chart. Post the frames from both tests where the smallest chart text legibility most closely matches the sample images in the ZIP file. Looking at the doll or whatever you put in the frame besides the chart, which image has a noise level you would consider acceptable to deliver to a paying client? Post 100% crops of both the chart and the doll or whatever, or better yet, DNGs.

I look forward to seeing the results with great interest.
[a href=\"index.php?act=findpost&pid=161453\"][{POST_SNAPBACK}][/a]

What does this have to do with anything I've said?  Obviously, the subject detail is going to be less when the subject fills less of the frame, exposure remaining equal.  When the target fills the frame, you can get the same resolution of the smallest text with a lower exposure.

Let me refresh what I am arguing (and Ray, and some others); measuring the DR range of the pixel is only about the pixel.  It only means something to the DR of the image when the number of them are also taken into account.

I don't have a working printer right now, so I can't print your target.  If you made it clear what you think you are proving, I could comment, though.
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Sheldon N

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« Reply #52 on: December 20, 2007, 10:38:02 am »

I think the heart of the dispute lies in the subjective assumption of what the final deliverable product will be. A lot of the MFDB guys are having to downsize for final delivery, and I'm guessing it's an issue for 1Ds Mk II/III shooters as well.

Are you making a 16x20 fine art print? Then Jonathan's assumption that pixel quality reigns supreme carries some merit.

Are you doing a 1/2 page spread for magazine reproduction? You certainly don't need 16 or 22 megapixels to do that and you can't ignore the DR/noise advantage that a high resolution camera gives when downsizing the final file.

Perhaps there needs to be a third metric in Jonathan's test that accounts for the difference. What about shooting full frame, then resizing to a standardized 8x10 at 300dpi (or any other standard print size)?
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John Sheehy

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« Reply #53 on: December 20, 2007, 12:16:42 pm »

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I think the heart of the dispute lies in the subjective assumption of what the final deliverable product will be. A lot of the MFDB guys are having to downsize for final delivery, and I'm guessing it's an issue for 1Ds Mk II/III shooters as well.

Are you talking about downsampling just to reduce noise?  It is utterly ridiculous if anyone has to do that.  It shows a visual naivite on the part of the recipient.  If you're talking about a limited resolution medium for display, then of course downsampling is necessary at some stage, and you might want to excercise quality control by doing it yourself.  It should ideally be done in the conversion process, especially with Canons, as Canons have RAW data that is ideal for downsampling near-blacks with a minimum of (chromatic) noise.

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Are you making a 16x20 fine art print? Then Jonathan's assumption that pixel quality reigns supreme carries some merit.

The point I have been trying to make is that unless you have your face so deep into the pixels that each is clearly distinct, pixel quality is irrelevant, except insofar as it affects image quality as a single factor (and bigger, cleaner pixels would look like a mosaic with similar overall noise).  Otherwise, I have never seen a single demonstration that shows lower noise for bigger but fewer pixels or binnings or downsamples.  It's just a mantra that many people repeat, without ever demonstrating its validity.

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Are you doing a 1/2 page spread for magazine reproduction? You certainly don't need 16 or 22 megapixels to do that and you can't ignore the DR/noise advantage that a high resolution camera gives when downsizing the final file.

Perhaps there needs to be a third metric in Jonathan's test that accounts for the difference. What about shooting full frame, then resizing to a standardized 8x10 at 300dpi (or any other standard print size)?
[a href=\"index.php?act=findpost&pid=162006\"][{POST_SNAPBACK}][/a]

That would standardize the "image noise" issue well, but is unfair to the camera(s) that lose more resolution in the downsampling.  That's why upsampling is preferable, IMO; then all cameras can show their full resolution and noise.
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Jonathan Wienke

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Canon 5D dynamic range tests
« Reply #54 on: December 20, 2007, 12:30:26 pm »

The metric I'm using is that I don't want to base my assessment of DR performance on an assumption of reducing the effective resolution of my camera. Yes, I know that one can sacrifice resolution for DR, but in most cases, I don't want to. So for me, knowing how much DR I can get without sacrificing resolution is if far more interest than knowing what I can get if I reduce resolution to web-JPEG levels. I expect a DR specification to hold true for the largest prints I expect to make, not the smallest. If I choose to trade away resolution for additional DR, I can still do so, but assuming that I will find that trade-off acceptable in every case is stupid.

Printing more native-resolution pixels will increase print quality until you pass 300-360 PPI, depending in the specific printer brand and print process. For a 12x18" print (which is NOT an unreasonably large size; well within the capabilities of the hobby-level photographer) that translates to ~19.5-28MP of native camera resolution before further increases cease to offer additional visible improvement. For prints that size, there's no reason for someone shooting with a 1Ds-MkIII or below to downsize before printing, and noise levels high enough to compromise pixel quality will degrade the image quality of such prints.
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Jonathan Wienke

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Canon 5D dynamic range tests
« Reply #55 on: December 20, 2007, 03:22:25 pm »

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(Image quality) = (pixel quality) * (pixel quantity).

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The square root of pixel quantity.

Better double-check your math there, your statement is only true if you're talking in terms of linear measurements in a single dimension, which I'm not. I'm talking about the quality of the image as a whole.
« Last Edit: December 20, 2007, 03:23:30 pm by Jonathan Wienke »
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John Sheehy

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Canon 5D dynamic range tests
« Reply #56 on: December 20, 2007, 04:56:59 pm »

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Better double-check your math there, your statement is only true if you're talking in terms of linear measurements in a single dimension, which I'm not. I'm talking about the quality of the image as a whole.
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No, I meant what I said.  That is exactly how noise resamples/bins.
« Last Edit: December 20, 2007, 04:58:50 pm by John Sheehy »
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Jonathan Wienke

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Canon 5D dynamic range tests
« Reply #57 on: December 20, 2007, 05:20:30 pm »

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No, I meant what I said.  That is exactly how noise resamples/bins.

And I'm talking about image quality when you DON'T resample or bin. Given pixels of a certain quality, if you double the pixel count, you can double the image area (note I'm NOT saying linear dimensions!) while maintaining a constant image quality per unit of area.
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John Sheehy

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Canon 5D dynamic range tests
« Reply #58 on: December 20, 2007, 07:31:06 pm »

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And I'm talking about image quality when you DON'T resample or bin.

Me too.  When did I ever imply that binning or resampling is necessary to increase image DR?

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Given pixels of a certain quality, if you double the pixel count, you can double the image area (note I'm NOT saying linear dimensions!) while maintaining a constant image quality per unit of area.
[a href=\"index.php?act=findpost&pid=162132\"][{POST_SNAPBACK}][/a]

Yes, and viewed at the same size, it can have 1.414x the DR (a half stop more), without any resampling to a resolution lower than the original.
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Jonathan Wienke

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« Reply #59 on: December 20, 2007, 08:05:38 pm »

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Me too.  When did I ever imply that binning or resampling is necessary to increase image DR?

You've only talked about adding pixels to increase DR in every single one of your posts. Here's a novel thought: perhaps when I increase pixel count, I wish to increase "image resolution" and not "image DR". To do that, I need to set a consistent per-pixel noise/quality standard.

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Yes, and viewed at the same size, it can have 1.414x the DR (a half stop more), without any resampling to a resolution lower than the original.

But only at the cost of NOT increasing resolution. You can have one or the other, but you don't get to have both. There is no free lunch here. Once noise starts negatively affecting resolution, you can add pixels to increase resolution or increase DR, but to the extent that you do one, you lose the ability to do the other. Is that so hard to understand?
« Last Edit: December 20, 2007, 08:06:57 pm by Jonathan Wienke »
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