If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#371
|
|||
|
|||
Finally got to the point where no new camera holds my interest (waiting for specific offering)
On Thu, 17 Jan 2019 11:19:16 -0500, Alan Browne
wrote: On 2019-01-17 09:22, Alan Browne wrote: The link you pointed to was referring to quantization noise in the frequency domain, not the amplitude which is the issue at hand here. Ooops... I should have said "time domain". Nevertheless, the principle remains, the digitization of a non-identical source signal can only be an approximation of the original signal. The differences/errors manifest themselves as noise. -- Regards, Eric Stevens |
#372
|
|||
|
|||
Finally got to the point where no new camera holds my interest (waiting for specific offering)
On Thu, 17 Jan 2019 10:34:04 -0500, nospam
wrote: In article , Eric Stevens wrote: (with today's short focal length lenses) not just short focal length, but all lenses at normal working distances because the difference is too small to matter, below the tolerance of the various components. Your statement is too sweeping. It matters with a 10" lens normally used for used for portraits and it matters more for a 105mm macro lense normally used for dental photography. nope, and dentists don't use 105mm macro lenses anymore. I must tell my dentist. He keeps it alongside his Cerec setup. See https://www.dentsplysirona.com/en/explore/cerec.html I think he is now on his third generation Cerec. this is not a 105mm macro lens: https://www.dentsplysirona.com/en/explore/cerec/scan-with-cerec.html For god's sake - read what I wrote! See also https://dictionary.cambridge.org/dic...lish/alongside --- flatulence snipped --- -- Regards, Eric Stevens |
#373
|
|||
|
|||
Finally got to the point where no new camera holds my interest (waiting for specific offering)
In article , Eric Stevens
wrote: I have never argued that "there is more information in 14 bits than there is in 14 bits". As you say, there can't be. What I have said from the beginning is that an analog signal of _any_dynamic_range_ can be coded in 14 bits. There is no reqirement imposed on the DR of the source device. yep, that is indeed what you've said. the problem is that it's incorrect, something which several people have told you and you stubbornly refuse to learn why. I have said this in so many ways so many times that I'm not going to try and repeat it any more. unfortunately, you still believe it. you haven't learned anything. |
#374
|
|||
|
|||
Finally got to the point where no new camera holds my interest (waiting for specific offering)
In article , Eric Stevens
wrote: I must tell my dentist. He keeps it alongside his Cerec setup. See https://www.dentsplysirona.com/en/explore/cerec.html I think he is now on his third generation Cerec. this is not a 105mm macro lens: https://www.dentsplysirona.com/en/explore/cerec/scan-with-cerec.html For god's sake - read what I wrote! i did. |
#375
|
|||
|
|||
Finally got to the point where no new camera holds my interest (waiting for specific offering)
On Thu, 17 Jan 2019 10:34:05 -0500, nospam
wrote: In article , Eric Stevens wrote: also, their 'tests' claim what is physically impossible, making them untrustworthy and their scale is whatever they want it to be, with newer cameras scoring higher and higher. Suspicion and innuendo. That's not evidence. the evidence is quite clear that they cannot be trusted *at* *all*. The evidence appears to be that you can/will not produce any evidence to support that statement. false, there is extensive evidence that dxo is a sham, but as usual, you refuse to acknowledge that and just want to argue, now having resorted to ad hominem attacks, as usual. their 'tests' claim what is physically not possible. that alone makes them a scam Example? - assuming of course that you are able to cite one. of course i'm able. i do not make false claims. period. --- Claim by nospam: ---- dxo measured 14.8 stops of dynamic range on the nikon d810 and d850, which is *higher* than the theoretical maximum of 14 stops (14 bit a/d) and in the real world, it won't actually get 14 stops. that's not *my* claim. it's basic sampling theory, something which you clearly do not understand at all. What is the frequency of the signal being sampled? I challenged this comment which lead to an enormous thread which fanned out in all directions. My contention was (and is) that the number of bits that are used to code an image have nothing to do with the dynamic range of the sensor. You can code it with as many bits as you like with factors other than dynamic range determining the choice. In particular there is no reason why a sensor should not have a dynamic range wider than implied by the number of bits with which it's output is encoded. your contention is wrong, which you even admitted in the middle of the thread. I bet you can't cite the article where I did that. At one stage Ron C suggested I should explain my views with diagrams. With some reluctance I have been getting round to doing this. Preparing the diagrams so as to be able to deal with nospams of tghis world is no mean task. In the course of my background research I found the following thread from dpreview dated Mar 25, 2012. https://www.dpreview.com/forums/thread/3170233 If you read that you will see that the maximum number of bits with which it is worthwhile coding an image is determined by (a) read noise and (b) pixel well size. DR vs number of bits is touched upon but no one has suggested that sensor DR is limited by bit number. the second post in that thread clearly does, further proof that you don't understand the topic. You mean where fvdbergh wrote "The dynamic range of a sensor is typically limited by the signal to noise ratio (SNR), not the bit depth of the analogue to digital converter (ADC)."? Please note fvdbergh lower down wrote "A single point on the PTC will give you the required SNR value, and hence the DR". http://www.forzasilicon.com/2011/06/...-image-sensor/ or http://tinyurl.com/y8ztqbhk will tell you that 'PTC' is 'Photon Transfer Curve' and says of this " the sub-ranging technique, where each segment’s conversion step size is scaled according to the photon transfer curve (PTC) of a given pixel." I have many times talked about scaling the sensor output to the ADC and you have repeatedly told me I was wrong. I think it it's safe to say you don't know as much of this subject as you you think you do and you understand even less. This hopefully is my last post on this subject. I also came across http://www.onmyphd.com/?p=analog.digital.converter which is a good summary of the basics of analog to digital convertors (ADC). Under the heading "What is an analog-digital convertor" the author has written: "An Analog-Digital Converter (ADC) is a widely used electronic component that converts an analog electric signal (usually a voltage) into a digital representation. The ADCs are at the front-end of any digital circuit that needs to process signals coming from the exterior world. ..... ---- complex text snipped ---- Therefore, more bits leads to more precision in the digital representation. Here we simplify the range to be between 0 and Vref, although the range may be between any two values." That last has always been my point. What is being encoded is a signal between gthe upper and lower limits to the sensitivity of the sensor. Their mathematical relationship (as in their ratio = dynamic range) does not come into the question. it is only their difference which matters. still not getting it. I'm not going to write any more about the original argument. nospam can go and find another playmate. I may be tempted to come back in if a sensible and rational discussion of a new aspect gets under way. Other than tghat I've finished with this thread. ad hominem, and it isn't just me who has been telling you that you're wrong. come back after you've learned about sampling theory. only then can there be a rational discussion. -- Regards, Eric Stevens |
#376
|
|||
|
|||
Finally got to the point where no new camera holds my interest (waiting for specific offering)
In article , Eric Stevens
wrote: their 'tests' claim what is physically not possible. that alone makes them a scam Example? - assuming of course that you are able to cite one. of course i'm able. i do not make false claims. period. --- Claim by nospam: ---- dxo measured 14.8 stops of dynamic range on the nikon d810 and d850, which is *higher* than the theoretical maximum of 14 stops (14 bit a/d) and in the real world, it won't actually get 14 stops. that's not *my* claim. it's basic sampling theory, something which you clearly do not understand at all. What is the frequency of the signal being sampled? you're confused. I challenged this comment which lead to an enormous thread which fanned out in all directions. My contention was (and is) that the number of bits that are used to code an image have nothing to do with the dynamic range of the sensor. You can code it with as many bits as you like with factors other than dynamic range determining the choice. In particular there is no reason why a sensor should not have a dynamic range wider than implied by the number of bits with which it's output is encoded. your contention is wrong, which you even admitted in the middle of the thread. I bet you can't cite the article where I did that. i could if i was motivated to sift through more than 500 posts to find it. At one stage Ron C suggested I should explain my views with diagrams. With some reluctance I have been getting round to doing this. Preparing the diagrams so as to be able to deal with nospams of tghis world is no mean task. In the course of my background research I found the following thread from dpreview dated Mar 25, 2012. https://www.dpreview.com/forums/thread/3170233 If you read that you will see that the maximum number of bits with which it is worthwhile coding an image is determined by (a) read noise and (b) pixel well size. DR vs number of bits is touched upon but no one has suggested that sensor DR is limited by bit number. the second post in that thread clearly does, further proof that you don't understand the topic. You mean where fvdbergh wrote "The dynamic range of a sensor is typically limited by the signal to noise ratio (SNR), not the bit depth of the analogue to digital converter (ADC)."? nope. i mean this pretty little pictu https://3.img-dpreview.com/files/g/TS560x560~1835042.jpg from this post, which is the second post in the thread: https://www.dpreview.com/forums/post/41016086 it's even marked in evs, although that will no doubt cause you massive confusion. I have many times talked about scaling the sensor output to the ADC and you have repeatedly told me I was wrong. nope, what i told you is that the sensor output *could* be scaled, but it isn't, therefore what you've said is not applicable. have you forgotten about your imaginary camera collection? I think it it's safe to say you don't know as much of this subject as you you think you do and you understand even less. that would be a very unsafe comment. it actually applies to you. This hopefully is my last post on this subject. hopefully, but i suspect not. either way, you haven't learned a thing. |
#377
|
|||
|
|||
Finally got to the point where no new camera holds my interest (waiting for specific offering)
On Thu, 17 Jan 2019 18:54:51 -0500, nospam
wrote: In article , Eric Stevens wrote: I wasn 't going answer this until I realised you had done some crude editing of the article to which you were replying. In other words a blatant lie. their 'tests' claim what is physically not possible. that alone makes them a scam Example? - assuming of course that you are able to cite one. of course i'm able. i do not make false claims. period. --- Claim by nospam: ---- dxo measured 14.8 stops of dynamic range on the nikon d810 and d850, which is *higher* than the theoretical maximum of 14 stops (14 bit a/d) and in the real world, it won't actually get 14 stops. that's not *my* claim. it's basic sampling theory, something which you clearly do not understand at all. What is the frequency of the signal being sampled? you're confused. https://whatis.techtarget.com/defini...yquist-Theorem "The Nyquist Theorem, also known as the sampling theorem, is a principle that engineers follow in the digitization of analog signals. For analog-to-digital conversion (ADC) to result in a faithful reproduction of the signal, slices, called samples, of the analog waveform must be taken frequently. The number of samples per second is called the sampling rate or sampling frequency. Any analog signal consists of components at various frequencies. The simplest case is the sine wave, in which all the signal energy is concentrated at one frequency. In practice, analog signals usually have complex waveforms, with components at many frequencies. The highest frequency component in an analog signal determines the bandwidth of that signal. The higher the frequency, the greater the bandwidth, if all other factors are held constant. Suppose the highest frequency component, in hertz, for a given analog signal is fmax. According to the Nyquist Theorem, the sampling rate must be at least 2fmax, or twice the highest analog frequency component. The sampling in an analog-to-digital converter is actuated by a pulse generator (clock). If the sampling rate is less than 2fmax, some of the highest frequency components in the analog input signal will not be correctly represented in the digitized output. When such a digital signal is converted back to analog form by a digital-to-analog converter, false frequency components appear that were not in the original analog signal. This undesirable condition is a form of distortion called aliasing." Now, bearing in mind that once the shutter has closed, a sensor site sits there fat and happy (or thin and misrable) with as many photons as the lens has thought to direct its way. No change. It's constant. The frequency of the signal being sampled (i.e the number of photons in the cell) is zero. According to Nyquist the sampling frequency must be 2 x zero = zero. In other words it only needs to be sampled once. Now what were you saying about sampling theory? I challenged this comment which lead to an enormous thread which fanned out in all directions. My contention was (and is) that the number of bits that are used to code an image have nothing to do with the dynamic range of the sensor. You can code it with as many bits as you like with factors other than dynamic range determining the choice. In particular there is no reason why a sensor should not have a dynamic range wider than implied by the number of bits with which it's output is encoded. your contention is wrong, which you even admitted in the middle of the thread. I bet you can't cite the article where I did that. i could if i was motivated to sift through more than 500 posts to find it. At one stage Ron C suggested I should explain my views with diagrams. With some reluctance I have been getting round to doing this. Preparing the diagrams so as to be able to deal with nospams of tghis world is no mean task. In the course of my background research I found the following thread from dpreview dated Mar 25, 2012. https://www.dpreview.com/forums/thread/3170233 If you read that you will see that the maximum number of bits with which it is worthwhile coding an image is determined by (a) read noise and (b) pixel well size. DR vs number of bits is touched upon but no one has suggested that sensor DR is limited by bit number. the second post in that thread clearly does, further proof that you don't understand the topic. You mean where fvdbergh wrote "The dynamic range of a sensor is typically limited by the signal to noise ratio (SNR), not the bit depth of the analogue to digital converter (ADC)."? nope. i mean this pretty little pictu https://3.img-dpreview.com/files/g/TS560x560~1835042.jpg from this post, which is the second post in the thread: https://www.dpreview.com/forums/post/41016086 Oh you persistent dummy! That's talking about the DR range coded into the digital output signal by the ADC. It is not, never was, and never will be the same as the DR of the analog input signal. (Maybe that's too sweeping a statement but you get the drift). it's even marked in evs, although that will no doubt cause you massive confusion. I have many times talked about scaling the sensor output to the ADC and you have repeatedly told me I was wrong. nope, what i told you is that the sensor output *could* be scaled, but it isn't, therefore what you've said is not applicable. OK. I will accept that. But I expect that's why you have snipped: ------------------------------------------------------------- You mean where fvdbergh wrote "The dynamic range of a sensor is typically limited by the signal to noise ratio (SNR), not the bit depth of the analogue to digital converter (ADC)."? Please note fvdbergh lower down wrote "A single point on the PTC will give you the required SNR value, and hence the DR". http://www.forzasilicon.com/2011/06/...-image-sensor/ or http://tinyurl.com/y8ztqbhk will tell you that 'PTC' is 'Photon Transfer Curve' and says of this " the sub-ranging technique, where each segment’s conversion step size is scaled according to the photon transfer curve (PTC) of a given pixel." I have many times talked about scaling the sensor output to the ADC and you have repeatedly told me I was wrong. I think it it's safe to say you don't know as much of this subject as you you think you do and you understand even less. -------------------------------------------------------------- Please note "... each segment’s conversion step size is scaled according to the photon transfer curve (PTC) of a given pixel." Independent evidence that scaling can occor in the ADC process. have you forgotten about your imaginary camera collection? I think it it's safe to say you don't know as much of this subject as you you think you do and you understand even less. that would be a very unsafe comment. it actually applies to you. This hopefully is my last post on this subject. hopefully, but i suspect not. either way, you haven't learned a thing. -- Regards, Eric Stevens |
#378
|
|||
|
|||
Finally got to the point where no new camera holds my interest (waiting for specific offering)
In article , Eric Stevens
wrote: I wasn 't going answer this until I realised you had done some crude editing of the article to which you were replying. In other words a blatant lie. nope. i snipped to eliminate irrelevant crap, other than yours, that is. consider it 'noise reduction', although the dominant noise source is not what was removed... dxo measured 14.8 stops of dynamic range on the nikon d810 and d850, which is *higher* than the theoretical maximum of 14 stops (14 bit a/d) and in the real world, it won't actually get 14 stops. that's not *my* claim. it's basic sampling theory, something which you clearly do not understand at all. What is the frequency of the signal being sampled? you're confused. https://whatis.techtarget.com/defini...yquist-Theorem "The Nyquist Theorem, also known as the sampling theorem, is a principle that engineers follow in the digitization of analog signals. For analog-to-digital conversion (ADC) to result in a faithful reproduction of the signal, slices, called samples, of the analog waveform must be taken frequently. The number of samples per second is called the sampling rate or sampling frequency. Any analog signal consists of components at various frequencies. The simplest case is the sine wave, in which all the signal energy is concentrated at one frequency. In practice, analog signals usually have complex waveforms, with components at many frequencies. The highest frequency component in an analog signal determines the bandwidth of that signal. The higher the frequency, the greater the bandwidth, if all other factors are held constant. Suppose the highest frequency component, in hertz, for a given analog signal is fmax. According to the Nyquist Theorem, the sampling rate must be at least 2fmax, or twice the highest analog frequency component. The sampling in an analog-to-digital converter is actuated by a pulse generator (clock). If the sampling rate is less than 2fmax, some of the highest frequency components in the analog input signal will not be correctly represented in the digitized output. When such a digital signal is converted back to analog form by a digital-to-analog converter, false frequency components appear that were not in the original analog signal. This undesirable condition is a form of distortion called aliasing." Now, bearing in mind that once the shutter has closed, a sensor site sits there fat and happy (or thin and misrable) with as many photons as the lens has thought to direct its way. No change. It's constant. The frequency of the signal being sampled (i.e the number of photons in the cell) is zero. According to Nyquist the sampling frequency must be 2 x zero = zero. In other words it only needs to be sampled once. you're even more confused than i thought. Now what were you saying about sampling theory? that it applies and there's no escaping it. unless you know something the rest of the world does not, that is, but if you really can disprove nyquist and sampling theory as we know it, then stop babbling on usenet and go write a paper, give some talks and change the world as we know it. At one stage Ron C suggested I should explain my views with diagrams. With some reluctance I have been getting round to doing this. Preparing the diagrams so as to be able to deal with nospams of tghis world is no mean task. In the course of my background research I found the following thread from dpreview dated Mar 25, 2012. https://www.dpreview.com/forums/thread/3170233 If you read that you will see that the maximum number of bits with which it is worthwhile coding an image is determined by (a) read noise and (b) pixel well size. DR vs number of bits is touched upon but no one has suggested that sensor DR is limited by bit number. the second post in that thread clearly does, further proof that you don't understand the topic. You mean where fvdbergh wrote "The dynamic range of a sensor is typically limited by the signal to noise ratio (SNR), not the bit depth of the analogue to digital converter (ADC)."? nope. i mean this pretty little pictu https://3.img-dpreview.com/files/g/TS560x560~1835042.jpg from this post, which is the second post in the thread: https://www.dpreview.com/forums/post/41016086 Oh you persistent dummy! That's talking about the DR range coded into the digital output signal by the ADC. which shows that a 14 bit adc limits it to 14 stops. imagine that. It is not, never was, and never will be the same as the DR of the analog input signal. (Maybe that's too sweeping a statement but you get the drift). otherwise described as "the dynamic range is limited by the adc". you said: DR vs number of bits is touched upon but no one has suggested that sensor DR is limited by bit number. except that someone did, with a nice picture too. so much for that idea. it's even marked in evs, although that will no doubt cause you massive confusion. I have many times talked about scaling the sensor output to the ADC and you have repeatedly told me I was wrong. nope, what i told you is that the sensor output *could* be scaled, but it isn't, therefore what you've said is not applicable. OK. I will accept that. But I expect that's why you have snipped: nope. i snipped it because it's not correct. you only quoted it because it says the same crap you've been parroting. |
#379
|
|||
|
|||
Finally got to the point where no new camera holds my interest(waiting for specific offering)
On 2019-01-17 17:28, Eric Stevens wrote:
On Thu, 17 Jan 2019 09:22:21 -0500, Alan Browne wrote: On 2019-01-16 23:43, Eric Stevens wrote: On Tue, 15 Jan 2019 19:42:49 -0500, Alan Browne wrote: On 2019-01-15 18:29, Eric Stevens wrote: On Mon, 14 Jan 2019 12:34:42 -0500, Alan Browne wrote: On 2019-01-13 21:07, Eric Stevens wrote: On Sun, 13 Jan 2019 10:06:13 -0500, Alan Browne wrote: On 2019-01-12 21:15, Eric Stevens wrote: On Sat, 12 Jan 2019 09:25:23 -0500, Alan Browne wrote: On 2019-01-11 18:18, Eric Stevens wrote: The recorded output of the ADC is limited by the capabilities of the ADC. But these have no effect on the capabilities of the sensor. If If there is no way to encode the information, then that is the mootest of moot points. That may well be but, as I have several times said, it is possible to scale the dynamic range of the sensor to fit the narrower dynamic range of the ADC. To which I've replied numberous times. In a nutshell, you're trading one form of noise for another. The 'scaling' is done during the conversion of analog to digital in the ADC and involves no more noise than is inherent in any analog to digital conversion. I've pointed out quantization noise to you several times. Ignore it. You ignore everything else. You always get quantization noise when you digitize. That's what I meant by 'inherent'. No. A sample is a sample. It contains signal and _sampling_ source noise (the noise of the thing being sampled and the noise of the ADC), but not quantization noise. In this case we are not considering sampling. We are dealing with digitizing of a static (as in remains constant) charge in the pixel well which has to be digitized as a proportion of the maximum charge when the cell is filled. Quantization noise is an artifact of data manipulation (such as scaling) and is completely unavoidable when doing such operations. Its also inevitable when digitizing an analog signal. Which you clearly don't understand. The link you pointed to was referring to quantization noise in the frequency domain, not the amplitude which is the issue at hand here. I was clearly referring to noise introduced by scaling or manipulation (amplitude). But you will continue to hunt for anything that violates the notion that there is more information in 14 bits than there is in 14 bits. There isn't. There can't be. Frequency or amplitude: the principle is the same. The difference here is very simple, however. Here (photography) you are sampling an static analog signal that has noise as part of the overall quantity. That noise is just random numbers in the lower bits... No quantizuation noise at all. Then you claim something special is a happening. No matter what that magic is (compression, dilation, re-mapping (LUT)), etc. will introduce quantization noise when the information is extracted. Because: 14 bits. This is _not_ related to time domain sampling quantization noise which is a different beast (which in any case should be taken care of by appropriate attention to Nyquist, but that's another story that belongs to sampling a signal over time...). I have never argued that "there is more information in 14 bits than there is in 14 bits". As you say, there can't be. What I have said from the beginning is that an analog signal of _any_dynamic_range_ can be coded in 14 bits. There is no reqirement imposed on the DR of the source device. The dynamic range is simply represented by bits of sample depth. That's the simplest way to look at it. If there was some sort of compression before that point then the benefit of it would be lost to quantization noise in the representation in 14 bits and then "re-conversion" to express it as more bits. It remains a fairy tale, IOW: TANSTAAFL. I have said this in so many ways so many times that I'm not going to try and repeat it any more. That's a good thing. Because it is as wrong after n repetitions as it was after the first. -- "2/3 of Donald Trump's wives were immigrants. Proof that we need immigrants to do jobs that most Americans wouldn't do." - unknown protester |
#380
|
|||
|
|||
Finally got to the point where no new camera holds my interest(waiting for specific offering)
On 2019-01-17 17:31, Eric Stevens wrote:
On Thu, 17 Jan 2019 11:19:16 -0500, Alan Browne wrote: On 2019-01-17 09:22, Alan Browne wrote: The link you pointed to was referring to quantization noise in the frequency domain, not the amplitude which is the issue at hand here. Ooops... I should have said "time domain". Nevertheless, the principle remains, the digitization of a non-identical source signal can only be an approximation of the original signal. The differences/errors manifest themselves as noise. Nothing to do with DR however... esp. not getting more than there is. -- "2/3 of Donald Trump's wives were immigrants. Proof that we need immigrants to do jobs that most Americans wouldn't do." - unknown protester |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Finally got to the point where no new camera holds my interest (waiting for specific offering) | Alfred Molon[_4_] | Digital Photography | 2 | December 24th 18 02:37 PM |
Please, tell me Zeiss's offering to the camera world won't be areskinned SONY!! | Neil[_9_] | Digital Photography | 1 | August 27th 18 01:00 PM |
Need a camera with specific features: | Gary Smiley | Digital Photography | 1 | May 22nd 06 02:31 AM |
Canon Offering $600+ Rebate on Digital Camera Equipment (3x Rebate Offers) | Mark | Digital Photography | 6 | November 4th 04 10:27 AM |