[filmscanners] RE: IV ED dynamic range... DYNAMIC RANGE!
You may use other filters but must be able to correlate to a "film density". This correlation is not linear and will be different for each scanner. The problem arises from the fact that a densitotemeter reads densities differently than a scanner. A densitometer captures all light passing through the media under test, while a scanner captures light entering through its lens aperture. -Original Message- From: Clark Guy [mailto:[EMAIL PROTECTED]] Sent: Thursday, August 08, 2002 3:08 PM To: [EMAIL PROTECTED] Subject: [filmscanners] RE: IV ED dynamic range... DYNAMIC RANGE! HI, Constantine! You are correct that if one adds uncontrolled light scattering into the mix of variables, one can obtain less reliablie results than if one eliminates it. I (for the purposes of discussion) chose to ignore scattering. In my tests at my old employers' labs, we used high quality glass filters, and later, when verifying the operation of our devices, we used high purity distilled water (in highly polished quartz cuvettes) with the appropriate dyes to minimize the effects of scattering. If a standard were created mandating the use of some particular type of filter set for scanner testing, all of you would be using the same standard, and your numbers would be comparable. I still maintain that this can be done, and at miniscule cost to the manufacturers of scanners. (compared to your advertising budgets, that is!) Guy -Original Message- From: Kapetanakis, Constantine [mailto:[EMAIL PROTECTED]] Sent: Thursday, August 08, 2002 1:49 PM To: Clark Guy Subject: [filmscanners] RE: IV ED dynamic range... DYNAMIC RANGE! That is wrong. The light scattering characteristics of different media are different. If i am not mistaken that is called the "Q-factor". Without elaborating much try this very simple experiment. Take two different media of similar densities, as measured with a densitometer i.e. a ccNeutral density filter and a gray scale target of either film or another base material. Scan both with the same scanner while disabling auto-exposure and you will get different results. Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] RE: IV ED dynamic range... DYNAMIC RANGE!
Hi Toodd, > > Ouch. Sigh. Dynamic range: > > 1. The difference, in decibels, between the overload level and > the minimum > > acceptable signal level in a system or transducer. > > > > 5. The difference between the maximum acceptable signal level and the > > minimum acceptable signal level. > > (Modern Dictionary of Electronics, 6th ed.) > > > > Austin is, of course, right on this one. > > I don't claim to know DyR better than anyone else but I have followed the > discussion for some time. So, I'm not sure why what you cite > above supports > Austin any better than Julian. > > My reading of Julian is that he is in full agreement/compliance > with what is > written above. Possibly, but it depends on how it and the terms used are "interpreted". I don't recall who believes what means what, but the terms CAN be ambiguous...and the ones cited certainly are. > I believe he feels DyR is exactly: 5. The > difference between > the maximum acceptable signal level and the > minimum acceptable signal level. > (Modern Dictionary of Electronics, 6th ed.) Again, what does "minimum acceptable signal level" mean? Is that the minimum measurable change in signal, or the lowest "voltage" the signal can attain What does "maximum acceptable signal level" mean? The largest amplitude the signal can attain, or the highest voltage the signal can attain? > My reading of Austin is that he believes DyR is the The difference between > the maximum acceptable signal level and the > minimum acceptable signal level, divided by noise, (where noise is > typically/frequently specified as 10. It depends. Using the definitions above, and using what I believe the terms mean, I'll define the terms here... Per definition 5 (because it's easier and more to the point): "maximum acceptable signal level" means the largest amplitude. It is EXACTLY the same as the largest voltage the signal can attain, minus the minimum voltage the signal can attain. "minimum acceptable signal level" means the smallest amplitude that can be measured. Typically, this is noise. If that is the definition of those two terms, than #5 is correct. You can extrapolate those definitions to #1 if you like, and therefore it's correct too... What happens is people don't understand the CONCEPT of dynamic range, and therefore don't understand what the terms actually mean...and draw a different understanding as to what dynamic range is. > > Comment: this went back and forth interminably, and I think most of that > > could have been avoided by actually quoting standard > definitions of the term > > and working from there. > > Just curious, would those standard definitions and terms BE what you quote > above? If so, lets see if it makes a difference. I doubt it will... That's the point, there ARE no standard definitions and terms... Austin Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] RE: IV ED dynamic range... DYNAMIC RANGE!
Peter, > Some time ago you promised us a paper setting out your definition, > derivations and sources. I HAVE provided definitions, clear, concise definitions. I have also clearly provided my assertions etc. I said I would write-up something, I never made any PROMISE to do so, nor stated any time frame for doing so. > Until you do this and circulate it, off forum, > to those of us who offered to do a peer review I suggest you keep quiet. I find your "request" unquestionably arrogant and completely out of line. I'll discuss what I want, within the guidelines of this newsgroup. > I don't want to get into a further debate until you verify your > assertions. I don't need to verify anything on this subject. What the purpose of my proposed paper was, was simply to provide all the information that I have already posted on this subject, as well as any other information I may have, plus possibly some diagrams explaining concepts further. As you somehow believe there is something wrong with my understanding of dynamic range (which I know are correct, and the ISO spec backs up my understanding as well), I suggest it is you who should "verify" his assertions. Austin Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: IV ED dynamic range... DYNAMIC RANGE!
I would agree with your comments IF: 1) indeed the competitors spec usage could be PROVEN to be in opposition to either standard practice or was indeed a misuse of terms. Based upon the "discussion" which occurred here recently regarding the use of "density range", "dynamic range", etc., it seems fairly hopeless. Partially speaking, this is because there have not been agreed upon definitions or standards within the industry. 2) the cost of the "educative" process would be shared among the players within the industry There is more than one way to damage a competitor. You can indeed play with the numbers to make your product spec out better and not play by the same "rules" as you competitors, or you can goad your competitor to spend their advertising budget on trying to prove that their competition is being dishonest... Individual companies lose when they try to prove someone else in their industry is being dishonest, and that is why you almost NEVER see these types of advertising campaigns used and even less often are they successful. And law suits are usually equally unsuccessful, again because the terms are intentionally slippery enough so no one is actually "lying". It ends up sounding like sour grapes, and the "correct" party is often more damaged by it than helped. In almost every case where the public was educated in these matters it was done through either neutral third parties, or by institutes which are specifically developed (and financed by a whole industry sector) to standardize specs because chaos ensured and the public was ignoring all stats and specs, since none could necessarily be trusted to be meaningful. Art Clark Guy wrote: > HI, Constantine! > > I disagree--- if the competition insists on using bogus specs, you should > stay above that, and point out the fact that the competitor's specs ARE > bogus, and why. > > Educate the consumer, don't try to BS us! It's been tried before by all > sorts of industries, with generally bad outcomes in the long term. (look at > the High Fidelity Audio community for example!) > > Thanx! > > Guy Clark > > -Original Message- > From: Kapetanakis, Constantine [mailto:[EMAIL PROTECTED]] > Sent: Thursday, August 08, 2002 9:58 AM > To: Clark Guy > Subject: [filmscanners] RE: IV ED dynamic range... DYNAMIC RANGE! > > > You are right. The max optical density of our ss120 scanner as an example is > about 3.6~3.7. We measure this we a slide we made in house on Velvia film. > Each step on the gray scale is .1 density units different and we look at the > point of clipping as the maximum density. > However, when Nikon starts advertising theoretical maximums of 4.2 ( 14 > bits) then we have to start advertising the same way. > > > Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] RE: IV ED dynamic range... DYNAMIC RANGE!
Hi Arthur, > Based upon the "discussion" which occurred here recently regarding the > use of "density range", "dynamic range", etc., it seems fairly hopeless. > > Partially speaking, this is because there have not been agreed upon > definitions or standards within the industry. Actually, that's not true. They are VERY standard within certain specific engineering areas...unfortunately, it's marketing, and people who don't understand (and not all engineers...and people who have an engineering title but aren't really "engineers"...understand this...) this... I believe the term "density range" is quite strait forward...but I must admit, the term "dynamic range" sounds a lot cooler ;-) Regards, Austin Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] RE: IV ED dynamic range... DYNAMIC RANGE!
Austin, I really don't want to dance, so I am not going to get into the "he said, she said thing" I am going to stick by my interpretation of what was said and how each of you has interpreted it. For now, I am not concerned with the "maximum acceptable signal", given that I understand everyone's interpretation of this to be the maximum amplitude short of "flat line" saturation (concept mine). I do not think anyone but possibly me is thinking in absolute terms of theoretically possible maximum amplitude of the signal beyond stauration, which may be unreadable or unmeasurable. I think in everone's practical case the notion of full saturation is the limiting case for maximum accpetible signal. However, turning to "minimum acceptible signal," if I understand you, you are holding that theoretically the dMax-dMin range is much broader than the dynamic range whose lower limit is limited by the base noise level and whose upper limit is limited by the flat line saturation level. In other words, the dynamic range is the readable range (a subset within the full dMax-dMin range) where the full range can theoretically extend beyond the dynamic range such that they may or may not be synonomous or identical. Julian, if I read him correctly seeks to define the dMax-dMin range as being that which already accounts for the base noise on the lower dMin end and the full saturation level on the dMax end; thus he is implicitly accounting for the basic noise level without making it an explicit part of the equation. Thus, his definition of dynamic range is the readable or measurable range and for all practical purposes identical to the dMax-dMin range. The phrases, "...in one scan. It is the instantaneous range the scanner can handle," I take to be throw away phrases where he is for purposes of simplicity and consistency with how specs are typically derived trying to eliminate the possibility that multiple passes could very well alte5r and extend the dynamic range by lowering the basic noise level on average. Thus, I hear both you saying basically the same thing but in slightly different words that include and exclude elements in definitions by assuption and stipulation. If I am wrong in my understanding of each or both of you, then I do not have the foggest idea what is being said and havve to figure that you are both crazy, leaving me the only sane one in the asylum. The King of Hearts always said that it was the rational sane world of engineers that were the crazy ones with the only sane ones being locked away in the asylum. When we get done all the word games, we will find that we are all engaged in merely an ecology of games that impact on each other but are separate and distinct games that we are playing with ourselves such that we are all two steps short of a twelve step table. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Austin Franklin Sent: Thursday, August 08, 2002 4:27 PM To: [EMAIL PROTECTED] Subject: [filmscanners] RE: IV ED dynamic range... DYNAMIC RANGE! Hi Laurie, > The whole damn thing turns on the phrase, "acceptable signal level." > Austin, if I read him correctly, holds that "acceptability" is defined as > being above the noise level at the low end; If you read the definitions used, both "terms" used "acceptable signal level". When used as "minimum", it, to me, means noise, when used as maximum, it mean the maximum amplitude of the signal (before clipping, or saturating or whatever...where the signal is still valid). > Julian probably implicitly > accepts this also. I do not believe this. What others, who do not believe my understanding of dynamic range, believe is that dynamic range is not based on noise, but on the largest value of density the device can detect, minus the smallest density value the device can detect, basically, dMax - dMin, and there is no noise in the equation... This is simply the density range, and is not the dynamic range. Here is what he said: "DYNAMIC RANGE on the other hand, is the smaller range within the Density Range that the scanner can capture AT ONE TIME i.e. dynamically i.e in one scan. It is the instantaneous range the scanner can handle." Which, of course, has nothing to do with what I believe dynamic range is. Austin Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: IV ED dynamic range... DYNAMIC RANGE!
Arthur Entlich wrote: > Partially speaking, this is because there have not been agreed upon ^^ > definitions or standards within the industry. That was supposed to read "Practically speaking"... Art Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: IV ED dynamic range... DYNAMIC RANGE!
I am trying to find my cyanide capsules... ;-) Art Austin Franklin wrote: > Hi Arthur, > > >>Based upon the "discussion" which occurred here recently regarding the >>use of "density range", "dynamic range", etc., it seems fairly hopeless. >> >>Partially speaking, this is because there have not been agreed upon >>definitions or standards within the industry. >> > > Actually, that's not true. They are VERY standard within certain specific > engineering areas...unfortunately, it's marketing, and people who don't > understand (and not all engineers...and people who have an engineering title > but aren't really "engineers"...understand this...) this... > > I believe the term "density range" is quite strait forward...but I must > admit, the term "dynamic range" sounds a lot cooler ;-) > > Regards, > > Austin Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: IV ED dynamic range... DYNAMIC RANGE!
I am only posting two replies to what has been posted during my overnight. This one is a short response to the nitty gritty of Austin's argument. The other includes replies in a single post to other points by everybody. There are two points I am addressing in this post: 1. Dynamic range is a range, not a resolution 2. Dynamic range is the range that the scanner can capture AT ONE TIME i.e. dynamically i.e in one scan I address them purely by providing the resource that Austin requests. For logical discussion, see other posts. 1. Dynamic range is a range, not a resolution * Julian: > > It is a simple enough concept. Most explicitly, dynamic RANGE is > > ***not*** > > the RESOLUTION, Austin: >Yes it absolutely is. Julian: > > and there is no book or standard that has ever said > > this. Austin: >Well, the ISO spec shows clearly it is exactly what I've said it is, as well >as every other resource I've posted on this subject before. I simply don't >understand where you get the resources for your misguided understanding of >it. YOU HAVE NO RESOURCES THAT SUPPORT YOUR BELIEF. Julian now replies: Hmmm. Here is the draft ISO spec, from http://www.pima.net/standards/iso/tc42/wg18/WG18_POW.htm . It is entitled "Photography Electronic scanners for photographic images Dynamic range measurements." Perhaps there is another ISO spec from which you are deriving your beliefs? Perhaps you could post it? ---direct quote from Proposed ISO standard--- 7.2 Scanner dynamic range The dynamic range is calculated from the Scanner OECF by: DR = Dmax - Dmin(7.2) DR = Scanner Dynamic Range Dmax = Density where the Signal to noise ratio is 1 Dmin = Minimum density where the output signal of the luminance OECF appears to be unclipped ---end quote from Proposed ISO standard--- (and OECF is opto-electronic conversion function) You will notice, it is exactly as I have described it, a RANGE. It is the range between Dmax and Dmin. It is not a resolution, there is no mention of resolution. Can you tell me then how this says that Dynamic Range is a resolution? 2. Dynamic range is the range that the scanner can capture AT ONE TIME Julian: > > DYNAMIC RANGE on the other hand, is the smaller range within the Density > > Range that the scanner can capture AT ONE TIME i.e. dynamically i.e in one > > scan. It is the instantaneous range the scanner can handle. Austin: >Absolutely not correct. Where on earth did you get that? Please please >provide any credible source that says anything to the such. The ISO spec >doesn't define dynamic range that way...nor do any of the resources I have >seen. On the contrary, the ISO standard states a fairly precise process in which the Dynamic Range is measured by scanning a single slide in a single pass. (They do repeat the same single-scan measurement several times to improve accuracy). Here is the relevant text, remembering that the dynamic range is calculated from the OECF: quote from proposed standard 6 Measuring the Scanner OECF The scanner OECF shall be calculated from values determined from a test chart 4 that consists of a density range higher than the range the scanner is expected to be able to reproduce. For reflective targets the density range shall be higher than the range of typical reflective media scanned on this scanner. Many scanners will automatically adapt to the dynamic range of the scene as reproduced on the film or reflective media and the luminance distribution of the film. The results may also differ if the scan mode is grey scale or RGB A minimum of 10 trials shall be conducted for each scanner OECF determination. A trial shall consist of one scan of the test chart. For each trial, the digital output level shall be determined from a 64 by 64 1 pixel area located at the same relative position in each patch. Identical, non-aligned patches may be averaged, or the patch with the least scanning artifacts, such as dust or scan lines, may be used. The scanner OECF so determined shall be used to calculate the resolution measurements for this trial. If the scanner OECF is reported, the final digital output level data presented for each step density shall be the mean of the digital output levels for all the trials 6.1 Scanner settings The scans for the determination of the scanner OECF shall be made in RGB or grey scale mode with a resolution set to the maximum sample frequency (given in Dpi or Ppi) divided by an integer to avoid interpolation R = Rmax / i R = scanning resolution Rmax = maximum scanning resolution of the scanner i = integer value (6.1) The scanner shall be set to automatic adaptation to the dynamic range and the digital values representing the dark
[filmscanners] Re: IV ED dynamic range... DYNAMIC RANGE!
"Julian Robinson" <[EMAIL PROTECTED]> wrote: > 1. Dynamic range is a range, not a resolution No, it's a ratio; a value measured in dB. As such, it implies a resolution, namely the number of divisions it makes sense to divide (quantize) the range into. > 2. Dynamic range is the range that the scanner can capture > AT ONE TIME i.e. dynamically i.e in one scan No. Dynamic here is meaning 4. in Random House "4. of or pertaining to the range of volume of musical sound." Dynamic ranges are basically volume measurements; that is, a dynamic range is a ratio of volumes, loudnesses, or, more generally, signal amplitudes. David J. Littleboy [EMAIL PROTECTED] Tokyo, Japan Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: IV ED dynamic range... DYNAMIC RANGE!
This is composed into a single post because I know that this topic is overexposed and frustrates many people. It frustrates me too, but it would be wrong not to try to correct misinformation which is propagated with such authority that it has succeeded in hijacking the moral and technical high ground on this authoritative list. The purpose of this list is to allow all of us to discuss and get a handle on exactly this kind of question. I know that Austin has a deserved great reputation amongst list members, partly because he is a prolific and unflagging contributor and has obvious technical knowledge. Just the same, for whatever reasons, the view he puts forward on dynamic range is not in accord with any textbook, paper or standard of which I am aware, and this "definition" misleads and distorts and confuses much consequential discussion. Worse than that, it has succeeded in stifling a lot of the useful discussion we should be having on a pretty basic topic because people have realised they don't understand this most basic aspect of scanning - in large part because they are confused by unnecessarily difficult and incorrect constructions of what dynamic range is. For those of you who have assumed that Austin's view is correct and therefore not attempted to read my earlier post in any detail - I beg you, please read what I wrote (first post headed "RE: IV ED dynamic range... DYNAMIC RANGE!") and try to follow the logic of it, don't just assume that any particular person has the natural authority here. I tried hard to make this post short-ish and non-engineering. If it makes any difference to you, I have at least as much experience with using Dynamic Range in my career as Austin so don't make any assumptions about level of knowledge based on presentation or style. Go and look at every definition of dynamic range you can find for yourself on the web or in textbooks - you will not find one which says that dynamic range is a resolution. It is a range. Answers to many posts below: At 23:06 08/08/02, Austin wrote: > > DYNAMIC RANGE on the other hand, is the smaller range within the Density > > Range that the scanner can capture AT ONE TIME i.e. dynamically i.e in one > > scan. It is the instantaneous range the scanner can handle. > >Absolutely not correct. Where on earth did you get that? Please please >provide any credible source that says anything to the such. The ISO spec >doesn't define dynamic range that way...nor do any of the resources I have >seen. Austin - in my other post you'll see that the draft ISO spec does support my assertion. You need to get over this mental block as to what the "dynamic" means in "dynamic range". Here is another very simple example to illustrate the distinction between Dynamic Range and the non-dynamic kind of range - a very simple distinction that people need to understand. Consider a basic analog 3-range voltmeter. It has a graduated scale, a needle, and you can switch between 3 ranges, 1v, 10V, 1000V. We can measure on this meter from max = full scale deflection, down to a min = the smallest graduation on the scale (let's say). The meter is divided into 100 graduations, this is equivalent to saying the *resolution* is 1/100th of full scale. So, on the 1V range we can measure from 0,01V to 1V. On the 10V range we can measure from 0.1V to 10V. On the 1000V range we can measure from 10V to 1000V. The "Dynamic Range" of this meter is max/min = 100 in each case. BUT, and here is the rub, this meter can - overall - measure voltages from 0.01V to 1000V. This is the total range or just the "range", the kind or range we talk about without the word "dynamic" in front of it. In this example, the "range" is 1000/0.01 = 100,000 to 1. So for this meter: total range = 100,000:1, and dynamic range = 100:1 Engineers might say that total range = 100dBV and dynamic range = 40dBV. The difference between these two figures is EXACTLY analogous to the difference between the Dynamic Range and "Density Range" of a scanner. Dynamic refers to "at one instant", it means the signal range of the thing without changing it's configuration. Same in radio, same in audio, same in signal theory, same in light. Notice that in above example the resolution is 1/100th of full scale. You could express this resolution if you wanted to as a number of distinguishable levels, i.e. 100. The number of distinguishable levels (i.e. loosely, the resolution) is the same *number* as the Dynamic Range. But they are not the same thing! And under different assumptions even the numbers would not be the same. More on that below. >Absolutely incorrect. Dynamic range is absolutely NOT a "range" as you >believe it is. It is what happens WITHIN "A" RANGE...or it would not >contain the word "dynamic". You are arguing against everything I have ever seen written... please save us from going on for days on this in hopeless spirals - just post your authoritative sources to support this. > A ran
[filmscanners] Re: IV ED dynamic range... DYNAMIC RANGE!
This is going to be my last on-forum comment on this. > I HAVE provided definitions, clear, concise definitions. I have also > clearly provided my assertions etc. I said I would write-up something, > I > never made any PROMISE to do so, nor stated any time frame for doing so. > I accept that you did not specify a time frame, but I do remember you agreeing that you would write up what you have been saying in a single document. It is clear that a number of us disagree with your definitions and assumptions and it would clarify things for all if you could put it all together. > > Until you do this and circulate it, off forum, > > to those of us who offered to do a peer review I suggest you keep > > quiet. > > I find your "request" unquestionably arrogant and completely out of > line. > I'll discuss what I want, within the guidelines of this newsgroup. > I am not trying to gag you, however you are rapidly losing the respect of the group by not even accepting that you /might/ be wrong. It is you who is arrogant by continually pushing your beliefs and not considering that may be right. I suspect you are in more "kill" files than most. If you give us some foundation for your arguments then we might stand a chance of even agreeing with you. > > I don't want to get into a further debate until you verify your > > assertions. > > I don't need to verify anything on this subject. What the purpose of my > proposed paper was, was simply to provide all the information that I > have > already posted on this subject, as well as any other information I may > have, > plus possibly some diagrams explaining concepts further. As you somehow > believe there is something wrong with my understanding of dynamic range > (which I know are correct, and the ISO spec backs up my understanding as > well), I suggest it is you who should "verify" his assertions. > This emphasises /your/ arrogance. I believe that you *do* need to verify things as it it you who is in the minority in much of this discussion. If you are an engineer/scientist of any merit you should at least be prepared to go back to fundamentals and work it out again, as many of us have tried to do on a number of occasions. The problem with debates in a forum such as this is that there is no way to force another contributor to answer a specific question. If you write it down as you go then you should be able to convince others that you are correct and we are wrong. Alternatively, someone else may spot the error in your reasoning and prove you to be wrong. This possibility, I suspect, is the reason you have not taken what I and others would consider to be the professional route. It is entirely possible (and indeed probable) that one or more of those who have been involved in this debate has the facts wrong. It is also possible to interpret new information in a way that fits the current understanding. I clearly remember you changing from not knowing anything about the ISO spec, to saying it was wrong, now to saying it supports you. I still look forward to seeing the paper; I hope it will clear up the misunderstanding that exists somewhere. I suspect that it all derives from a mis-interpretation of definitions somewhere down the line. Please not that I am not, at this stage, saying that it is you who has made the mistake. You may be right, but the rest of us need convincing and repeatedly shouting "I'm right and you're wrong" is not the way to do it. Peter, Nr Clonakilty, Co Cork, Ireland Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] RE: IV ED dynamic range... DYNAMIC RANGE!
Julian, > Julian now replies: > > Hmmm. Here is the draft ISO spec, from > http://www.pima.net/standards/iso/tc42/wg18/WG18_POW.htm . It is > entitled > "Photography Electronic scanners for photographic images > Dynamic range > measurements." Perhaps there is another ISO spec from which you are > deriving your beliefs? Perhaps you could post it? You should know this is the same spec. This spec, when understood, shows exactly what I've been saying is correct, and shows that your belief is incorrect. It is merely corroboration I am deriving from it. But of course, if you don't understand or misinterpret the terms, and the basis for using them, you simply can't understand what this really means...and therefore can easily be misinterpreted to mean something it simply doesn't, which you are doing here. > ---direct quote from Proposed ISO standard--- > > 7.2 Scanner dynamic range > > The dynamic range is calculated from the Scanner OECF by: > > DR = Dmax - Dmin(7.2) > > DR = Scanner Dynamic Range > Dmax = Density where the Signal to noise ratio is 1 > Dmin = Minimum density where the output signal of the luminance OECF > appears to be unclipped > > ---end quote from Proposed ISO standard--- > > (and OECF is opto-electronic conversion function) > > You will notice, it is exactly as I have described it, a RANGE. I do not see ANYWHERE where it says dynamic range is "a" range. It shows the RESULT of a calculation WITHIN A RANGE (Dmax), divided by the noise (Dmin), but the result is NOT "a" range. It shows (in non-log numbers): dynamic range = amplitude / noise and in log math, division is merely subtraction: Non log example: 1000/10 = 100 log example: log 1000 = 3 (10**3 = 1000) log 10 = 1 (10**1 = 10) 3 - 1 = 2 and 10**2 = 100...fancy that. > It is the > range between Dmax and Dmin. No, that's Dmax MINUS Dmin. That's a MINUS sign there, Julian, it's a mathematical equation. The result IS the dynamic range. It is NOT "the range BETWEEN", it is the result OF the subtraction of two log values...which, BTW, is exactly the same a DIVISION if the numbers were NOT log values. Think about that. > It is not a resolution, there is no > mention of > resolution. Can you tell me then how this says that Dynamic Range is a > resolution? Very easily. One of the terms (Dmin) is the noise, as CLEARLY stated (Signal to Noise Ratio = 1...which means the noise equals the signal), and the minimum increment of measurability in a system IS noise...and therefore, you can only measure so many points within the overall range and consider them discrete points. The other term (Dmax) is simply the overall amplitude the signal can reach, which is based on zero being the low bound, and Dmax as being the high bound. If you divide the overall amplitude by noise, that gives you the resolution within that overall range with which you can discern. > Julian: > > > DYNAMIC RANGE on the other hand, is the smaller range within > the Density > > > Range that the scanner can capture AT ONE TIME i.e. > dynamically i.e in one > > > scan. It is the instantaneous range the scanner can handle. > > Austin: > >Absolutely not correct. Where on earth did you get that? Please please > >provide any credible source that says anything to the such. The ISO spec > >doesn't define dynamic range that way...nor do any of the > resources I have > >seen. > > On the contrary, the ISO standard states a fairly precise process > in which > the Dynamic Range is measured by scanning a single slide in a single > pass. (They do repeat the same single-scan measurement several times to > improve accuracy). So what? You HAVE to scan something to measure the relevant terms...duh!!! How is that "contrary"? This is called "practical application", as apposed to "theory". It's a good thing to be able to actually test what the Dynamic Range of a system is...instead of simply calculate it based on component specifications. > Austin, I have looked long and hard through archives to find > where you have > quoted supporting information for your views, without success. There is > not a single quote I can find anywhere which contradicts what I > am saying. I have ALWAYS contradicted what you're saying. You CLEARLY mistakenly believe "dynamic range" is "a" range, and it is clearly not. A range requires two bounding terms (or one with the other being considered 0, or simply the overall range, as in the amplitude), and dynamic range, as per the equation you have provided, shows that it is a number, that is in dB, that is derived from the information available WITHIN a particular range (DMax is the overall range), and that does not make it "A" range. A VERY simplified example that I've used time and time again while contradicting what you have been saying, but you seem to fail to grasp: A RANGE of 0-5V (which could be stated as a range of 5V) with 1V noise has a dynamic range of (5-0)/1 or 5.
[filmscanners] RE: IV ED dynamic range... DYNAMIC RANGE!
> > ---direct quote from Proposed ISO standard--- > > > > 7.2 Scanner dynamic range > > > > The dynamic range is calculated from the Scanner OECF by: > > > > DR = Dmax - Dmin(7.2) > > > > DR = Scanner Dynamic Range > > Dmax = Density where the Signal to noise ratio is 1 > > Dmin = Minimum density where the output signal of the luminance OECF > > appears to be unclipped > > > > ---end quote from Proposed ISO standard--- > > > > (and OECF is opto-electronic conversion function) > > > > You will notice, it is exactly as I have described it, a RANGE. > > I do not see ANYWHERE where it says dynamic range is "a" range. It shows > the RESULT of a calculation WITHIN A RANGE (Dmax), divided by the noise > (Dmin), but the result is NOT "a" range. Sorry, in my haste to get out of the house, I transposed Dmax and DMin in this post...obviously, as defined above, Dmax is the noise level, and Dmin is the "overall range". > Very easily. One of the terms (Dmin) is the noise, as CLEARLY stated Should be Dmax... > (Signal to Noise Ratio = 1...which means the noise equals the signal), and > the minimum increment of measurability in a system IS noise...and > therefore, > you can only measure so many points within the overall range and consider > them discrete points. > > The other term (Dmax) is simply the overall amplitude the signal can reach, > which is based on zero being the low bound, and Dmax as being the high > bound. If you divide the overall amplitude by noise, that gives you the > resolution within that overall range with which you can discern. Here too... > I have ALWAYS contradicted what you're saying. You CLEARLY mistakenly > believe "dynamic range" is "a" range, and it is clearly not. A range > requires two bounding terms (or one with the other being considered 0, or > simply the overall range, as in the amplitude), and dynamic range, as per > the equation you have provided, shows that it is a number, that is in dB, > that is derived from the information available WITHIN a particular range > (DMax is the overall range), and that does not make it "A" range. and here too... Sorry about that. Austin Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: IV ED dynamic range... DYNAMIC RANGE!
on 8/9/02 10:29 AM, Austin Franklin wrote: >> You will notice, it is exactly as I have described it, a RANGE. > > I do not see ANYWHERE where it says dynamic range is "a" range. It shows > the RESULT of a calculation WITHIN A RANGE (Dmax), divided by the noise > (Dmin), but the result is NOT "a" range. Austin, First off (Dmin) I was hoping to see how you'd respond to Julian's point that MDS is not always defined by noise. Your eq is based upon noise, but all definitions reference min disc signal. Where are you when the min disc signal is not defined by noise? > A VERY simplified example that I've used time and time again while > contradicting what you have been saying, but you seem to fail to grasp: > A RANGE of 0-5V (which could be stated as a range of 5V) with 1V noise > has a dynamic range of (5-0)/1 or 5. > > A RANGE of 0-5V with 1/2V noise has a dynamic range of (5-0)/1/2 or 10. > > Note, the RANGE is identical, but the DYNAMIC RANGE is not. I don't get how you can have a range of 5-0 when noise is 1. How do you get a range below noise? Doesn't noise limit your range on the low end, ie define your MDS, just as saturation/clipping does on the high end? Seems to me in your examples above you'd have two choices for each scenario: > A RANGE of 0-5V (which could be stated as a range of 5V) with 1V noise This could be ISO = DR = Dmax - Dmin = 5 - 1 = 4, which I *think* is how Julian would approach it. or Austin = DR = range/noise = (5 - 1)/1 = 4 which would appear to account for noise twice, though when noise is assigned a value of 1 it doesn't affect the final DR value (while conceptually it's way different). > A RANGE of 0-5V with 1/2V noise This could be ISO DR = Dmax - Dmin = 5 - .5 = 4.5 or, Austin DR =(5 - .5)/.5 = 9 Obviously, I must be mistaken about my assumption of noise and MDS... But the greater surprise is your definition of Dmax as a range. For your interpretation to make sense, your Dmax would need to be the entirety of what Julian considers to be dynamic range. For instance, if you were determining the the DR of a frame of film, isn't Dmax just the max density of the film? By your definition Dmax would be the entire density range of the film? So is DR effectively = density range / noise? If it were that it would be pretty easy to say so. Never seen it in any of the sources cited. The problem is that where sources are cited as definitions, those same sources don't also show numbers applied in the formula, so we can't see who's approach they support. Todd Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: IV ED dynamic range... DYNAMIC RANGE!
Hi Andre, I am NOT the list owner here, and the following views are my own. I have been with this list since its earliest beginnings, however, and am a fairly active poster. Having clarified that, here are my views: Welcome to "free speech". I know of no newsgroups or lists that do not have off topic or personal disagreements develop on occasion. Quite honestly, having been on this list for years, if you are unable to use the delete feature of your email browser when you encounter an off topic posting, you will become rather frustrated. There are many posters here who provide some very useful and valuable information, and some of them also go off topic or get into personal attacks and issue on occasion. Even if the list owner ruled with an iron fist, and in this list the owner both chooses not to, nor does he have the time to, some of this stuff would leak through, and also, as a community of people, it would be a much more boring list and I know a number of very active and helpful members would simply leave if the topic range was rigidly controlled. Basically, what it comes down to is that if you want more signal and less noise, then contribute signal, not noise. If you are here to watch and "listen" you are certainly welcome, but you cannot dictate policy or content. Art PS: I would also suggest you develop better quoting habits, it was unnecessary to post the whole message below again. Andre Moreau wrote: > I just subscribed yesterday thinking this would be a great scanning > discussion group but I get these kind of post cluttering my mail box. Makes > me want to unsubcribe right now!!! > > > - Original Message - > From: "Austin Franklin" <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]> > Sent: Friday, August 09, 2002 10:35 AM > Subject: [filmscanners] RE: IV ED dynamic range... DYNAMIC RANGE! > > > Peter, > > Your entire post has absolutely nothing to do with filmscanners. It is > simply your belief and critique about me, and appears to be an attempt to > throw dispersion on my credibility. If you want to comment on me > personally, as opposed to something technical, I believe you should keep it > OFF LIST, or not say it at all. > > Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] RE: IV ED dynamic range... DYNAMIC RANGE!
> Basically, what it comes down to is that if you want more signal and > less noise, then contribute signal, not noise. If you are here to watch > and "listen" you are certainly welcome, but you cannot dictate policy or > content. Hi Arthur, I agree with what you said, and I'm sure you know this...but one person's signal may very well be another person's noise. Regards, Austin Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
