[filmscanners] Re: Density vs Dynamic range
A man of God speaks...and having spoken speaks yet again and no doubt in due course will perform a miracle which migh, with any luck at all, include keeping his mouth well and truly shut more often than before Now sod off you jerk - Original Message - From: Austin Franklin [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Monday, June 10, 2002 9:16 PM Subject: [filmscanners] RE: Density vs Dynamic range Yeah, but Dickbo...obviously you don't understand what it means. It's got errors in it...but corrected, it's saying exactly what I've been saying. Like I said, you just don't understand this stuff, and don't want to. Austin -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of dickbo Sent: Monday, June 10, 2002 3:42 PM To: [EMAIL PROTECTED] Subject: [filmscanners] Re: Density vs Dynamic range Nice one Cyril - Original Message - From: Shough, Dean [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Monday, June 10, 2002 7:11 PM Subject: [filmscanners] RE: Density vs Dynamic range ... I'd like to follow this through to a definitive source. The proposed ISO standard on Photography - Electronic scanners for photographic images - Dynamic range measurements (WD 21550.3 (42N 4909)) states that the dynamic range is calculated by: DR = Dmax - Dmin 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 (opto-electronic conversion function) appears to be unclipped They go on to define a standard method for defining the signal to noise ratio using the concept of incremental gain. Incremental gain allows the signal to noise ratio to be determined independent of gamma. 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: Scene brightness and CCDs
Todd writes: Seems to me a good S curve algorithm could juice the midtones and still keep the highlights and shadows from from blowing and blocking, no? Absolutely, and an S curve is what I had in mind (although I don't actually know for sure what sort of adjustment the cameras are performing). In order to give images more pop, the processing would logically increase the change in luminosity in the midtones, where most of the information in a properly-exposed image would be, and sacrifice detail in the highlights and shadows. A plain straight-line change would work okay, but then highlights and shadows would be abruptly cut off, and they would contain more detail than necessary for most images up to the cutoff points, to the detriment of midtones. In other words, I'd expect image-processing software to emulate the same type of curve that is built into film emulsions, with a steep midsection and a toe and shoulder at the extremes. Of course, same curve = same drawbacks, so highlights and shadows will suffer. But unless you have a magic display device that can actually display a very wide gamut and a very broad dynamic range, you have to compress something. Some digicams may be overdoing it, by forcing images into the lowest-common-denominator gamut, which would be something like sRGB. I guess this is understandable for the consumer cameras, but I should hope that the pro cameras are using something wider, or even allowing the user to select a space for rendering of an image (including raw data from the CCD, preferably, which would mean no manipulation at all). Even better would be to do this all in the analog realm, with the raw output signals from the CCD, rather than trying to adjust after conversion to digital data, because some resolution will be lost in the conversion, unless it is extremely precise internally (18-20 bits, for example). But that would be expensive, inflexible, and prone to misadjustment and environmental influences, so I doubt that it is being done. Will the RAW captures from these cameras hold detail at the extremes under conditions of large brightness ranges? How many stops of brightness for the RAW captures? I don't know. It depends what RAW means for a given model of camera. Also, even the pro cameras today are using CCDs that are too small to provide the full benefits of CCD capture. The smaller the pixel, the less charge you can hold on a given photosite, and the smaller the dynamic range of the CCD. You need big pixels to provide lots of range, and to maintain resolution, then, you also need a big CCD. This is an argument in favor of full-frame 24x36 CCDs, but nobody has them yet (practically). Another problem is thermal noise, but you'd have to actively refrigerate a CCD to really drive it down and realize the full benefits of CCD range at the shadow end. That's probably not practical in a portable camera. Fortunately, it shouldn't be much of an issue except for really long exposures or really warm environments. Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: Density vs Dynamic range
Dickbo, A man of God speaks...and having spoken speaks yet again and no doubt in due course will perform a miracle which migh, with any luck at all, include keeping his mouth well and truly shut more often than before Now sod off you jerk Can you stop this please? This is an email list, not a house of parliament. Swearing and offensive wording is inappropriate here. I bet you wouldn't have said the words you've just written if it had been in a face-to-face argument, so please don't use them here either. - Original Message - From: Austin Franklin [EMAIL PROTECTED] To: [EMAIL PROTECTED] Please note that Austin's email was sent to your private address, not the list, and you published it without his consent. This isn't good practice, probably even illegal. Let this thread rest in peace once and for all. Andras Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: Scene brightness and CCDs
Austin writes: How's that that ...result in a photograph containing virtually no contrast...? Using a wide gamut, the midtones are very compressed with respect to the overall range of the image. When you display this on a device that doesn't have much range compared to the gamut, the midtones will lack contrast. This is easy to see just by playing around with different color spaces in Photoshop. P.S. I would comment more on this discussion... but simply don't have the time, and the other discussion I'm entertained with is rather time consuming...and more important, at least to me. Good. Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: Archiving and when to sharpen(was:Color spaces for differentpurposes)
Laurie writes: Don't you have this reversed? My understanding is that JPEG is lossy while TIFF with LZW is lossless. Yes, I do, sorry. Fortunately, you understood what I meant, not what I wrote. I was in a rush, as usual. Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: To Austin and Dickbo; Was: Density vs Dynamic range
And give yourself each 30 paces, a six iron, and wait until high noon! Art [EMAIL PROTECTED] wrote: Take it off line. Bill Kennedy Austin, Texas Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: Density vs Dynamic range
dickbo, I've sat back without saying anything watching this crap dribbling from your mouth for quite some time now , as I am sure a lot of other people have. I think the best thing you could do is take a course in anger management, you obviously have problems dealing with people that disagree with you. I have seen people like you on other lists. Belligerent, ill-mannered and smart-assed. Maybe it was you then too? All that happens is a lot of people get pissed off with the drivel that emanates from your mouths and many unsubscribe because this is NOT what we are here for. We are here to help each other and to learn from each other in a civil and friendly manner, even when there are disagreements. Here in the Antipodes, old chap, you would simply be labelled as a wanker and told to f*** off out of it. So why don't you? Geoff - Original Message - From: dickbo [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Tuesday, June 11, 2002 5:28 PM Subject: [filmscanners] Re: Density vs Dynamic range A man of God speaks...and having spoken speaks yet again and no doubt in due course will perform a miracle which migh, with any luck at all, include keeping his mouth well and truly shut more often than before Now sod off you jerk - Original Message - From: Austin Franklin [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Monday, June 10, 2002 9:16 PM Subject: [filmscanners] RE: Density vs Dynamic range Yeah, but Dickbo...obviously you don't understand what it means. It's got errors in it...but corrected, it's saying exactly what I've been saying. Like I said, you just don't understand this stuff, and don't want to. Austin -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of dickbo Sent: Monday, June 10, 2002 3:42 PM To: [EMAIL PROTECTED] Subject: [filmscanners] Re: Density vs Dynamic range Nice one Cyril - Original Message - From: Shough, Dean [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Monday, June 10, 2002 7:11 PM Subject: [filmscanners] RE: Density vs Dynamic range ... I'd like to follow this through to a definitive source. The proposed ISO standard on Photography - Electronic scanners for photographic images - Dynamic range measurements (WD 21550.3 (42N 4909)) states that the dynamic range is calculated by: DR = Dmax - Dmin 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 (opto-electronic conversion function) appears to be unclipped They go on to define a standard method for defining the signal to noise ratio using the concept of incremental gain. Incremental gain allows the signal to noise ratio to be determined independent of gamma. 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 Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: Density vs Dynamic range
I sir, will desist from all reference to the Rev Franklin the minute he comes to his senses and desists in his turn from making his untterly unproductive comments on my written communications to this list. Failing that, I reserve the right to express myself regarding his egotistical tendencies in any way that I deem appropiate. What the Rev want's, most of the time, is a straight forward argument conducted in such a way as to allow him to show off his technical grasp on any chosen issue. In other words he has a very big head. I do not care what he posts in response to any other individuals contribution but I do care that he choses to exercise his revoltingly conceited and entirely provocative views on the value of my postings. As his sense of self worth would appear to prevent him from respecting my wishes on this issue than I feel quite free to express my view of him in any way that suits me. Amen - Original Message - From: Major A [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Tuesday, June 11, 2002 8:46 AM Subject: [filmscanners] Re: Density vs Dynamic range Dickbo, A man of God speaks...and having spoken speaks yet again and no doubt in due course will perform a miracle which migh, with any luck at all, include keeping his mouth well and truly shut more often than before Now sod off you jerk Can you stop this please? This is an email list, not a house of parliament. Swearing and offensive wording is inappropriate here. I bet you wouldn't have said the words you've just written if it had been in a face-to-face argument, so please don't use them here either. - Original Message - From: Austin Franklin [EMAIL PROTECTED] To: [EMAIL PROTECTED] Please note that Austin's email was sent to your private address, not the list, and you published it without his consent. This isn't good practice, probably even illegal. Let this thread rest in peace once and for all. Andras 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: Scene brightness and CCDs
I would hope digicam raw files from the higher end equipment would offer this capability to some degree. And for normal (not raw) output one might possibly be able to recover some useful extremes if digicam processing was s-curve-like, not clipping. Hi Bob, I have a couple of very high end digital cameras (not 35mm-esque variants), and I simply don't see the issues that some are discussing here...and I unfortunately (or fortunately, for some I'm sure ;-) haven't had the time to really delve into this discussion as I would have liked to... BTW, I have an interface exactly like a scanner interface to one of my digital cameras...where I set the setpoints, and adjust the curves etc. and get the image... Obviously, for studio work only... 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: Density vs Dynamic range
At 08:52 AM 6/11/2002 +, you wrote: Group - I couldn't agree with Geoff more, and have commented about dickbo's toxic mouth in the past. I wonder why he is still allowed to be on this list at all. One doesn't have to be from the Antipodes to be offended by a living cesspool. Rodger Kingston This won't be the first list dickbo has been kicked off of, nor will it be the first time he has been kicked off this list, if my recollection is right. He shows up every so often under a different name, contributes a little bit, but then degenerates to name calling, ranting, raving, and threats (...make your life a living hell). He just doesn't understand how to discourse civilly and is completely unable to handle the concept that someone might disagree with him or know more than he does. I find him amusing at times, but he really has very little to offer other than amusement. If he offends you, just add his name to your kill file. I'm sure that, sooner or later, he will be removed from the list and then in a few days or weeks he'll be back again by a different name. Stan Photography by Stan McQueen http://www.smcqueen.com Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] RE: Dickbo
HI, Austin! That looks like him! Exactly the same attitude, obnoxious personality and use of English colloquialisms. I vote for his expulsion. Guy -Original Message- From: Austin Franklin [mailto:[EMAIL PROTECTED]] Sent: Tuesday, June 11, 2002 11:07 AM To: Clark Guy Subject: [filmscanners] RE: Dickbo Hi Guy, Yes, good call!!! You mean this guy ([EMAIL PROTECTED]): To: [EMAIL PROTECTED] Sent: Friday, March 30, 2001 4:16 PM Subject: RE: filmscanners: OT - Dicky returns to form.. ...Dicky... First swearing, racism and insults, now just insults.. That's not what I am here to see. Yes, but it is progress ;-) ...and I'll bet you voted Republican you grinning loon. Come on Mr Moderator, of topic, off topic, and off with his American head if I had anything to do with this issue. Richard - tea drinker - Corbett -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Clark Guy Sent: Tuesday, June 11, 2002 11:33 AM To: [EMAIL PROTECTED] Subject: [filmscanners] Dickbo HI, Austin! Don't you remember Richard Corbett aka Dickie, removed from this list some year ago or so? I think this person is one and the same! (Exactly the same prose style and abrasive personality.) Personally, I hope he is removed from the list again! There is certainly no fool like an old fool, and he certainly is one! (although he sounds like a 12 year old, he claims to be in the old age pensioner agegoup!) My opinion and I am welcome to it! Guy Clark 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: Scene brightness and CCDs
Austin writes: Isn't that a curve issue if you say it's only in the mid tones? It might be, if that were what I had actually said. But I only mentioned the midtones; I did not say that only they were affected. If you divide a 100:1 ratio of luminosity into 256 equal parts, the middle five stops (the midtones) will be divided into only 64 discrete levels, and will represent only 25% of the total dynamic range. If you divide a 1000:1 ratio of luminosity into 256 equal parts, these same midtones will be divided into 128 levels, or half of all available levels, and half of the total dynamic range. If the bulk of your image is recorded in midtones, as would be typical for most images, properly exposed, the former gamut will give you only half the tonal resolution and contrast of the latter. And if you attempt to improve contrast by boosting the increments between the midtones with an S curve, you risk posterization in the first case, but much less so in the second. This is why wide gamut shows poor contrast in midtones if displayed as-is, and why it may produce unacceptable results if you simply try to play with the curves. Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: Density vs Dynamic range
If the term, resolution, is not designated the same thing as indicated by ppi, dpi, line pairs, and numbers of pixels but is being used differently or to designate something entirely different then knowing this is the case would reduce my confusion and clarify the comments for this layman. I'm sorry if us electronics types have confused you (and probably ourselves :-) Resolution in photographic terms means, as you say, ppi etc. Resolution also refers to the size of the steps in the grey scale. An 8-bit gives 256 possible values - a resolution of 1/256. A 14-bit system gives 16384 possible values - a much finer resolution. 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: Density vs Dynamic range
Julian, I am in total agreement with you. 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: Density vs Dynamic range
Austin, This will be my last posting on this as we are (now) broadly in agreement. One cause of the disagreement has been your use of terms that have had an agreed understanding in the engineering world since long before scanners in a non-standard way. I realise that you may have been encouraged into this usage by the scanner industry, but it doesn't make it any less confusing to the rest of us. In engineering terms you are confusing dynamic range with signal-to-noise ratio. I will make one final comment. In the post, to which this is a reply, you said: So, where on earth did you get the idea that I believe that I fail to understand that increasing the number of bits from the AtoD does not necessarily increase the dynamic range of the scanner OBVIOUSLY from my four clips above, and ESPECIALLY the last one it should be bloody obvious that I completely understand what you believe I do not. However, at 10:32 yesterday, you said: However my point is that if you can reduce the noise level then you can increase the number of steps (by halving the step size) with real benefit, but without altering the range. Correct, but that INCREASES the dynamic range. Does not the first clip say no increase of dynamic range and the second say increases the dynamic range? I rest my case m'lud. Peter, Nr Clonakilty, Co Cork, Ireland (To avoid confusion, British born and educated - recent move to Ireland) Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: Density vs Dynamic range
Woah, Peter...what non-engineering standards are you talking about? What I specifically quoted as the formula for dynamic range is straight out of an engineering Bible for signal processing. I've also been an engineer in this VERY field for more than 20 years, so I don't understand why you believe anything I've said is not in adherence to ... non-engineering standards. In fact, the equation below is exactly the same as I've been saying all along, and meets with every aspect of what I've said. I was going to say no more, but I can't let this one through. Your diagram, as you have said, is taken from a document on DIGITAL signal processing. It is only valid in the real (analogue) world when the A/D step size is approximately the same as the noise level in the analogue system. My understanding is that the current performance of CCDs is better than that. 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: Dickbo
Guy writes: I vote for his expulsion. Consider following my example instead. Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: Density vs Dynamic range
On Tue, 11 Jun 2002 11:46:10 -0500, Laurie Solomon wrote: Thank you for this very lucid and clear definition;s clarify things for me on this front with respect to the concept of resolution. Then, am I correct in saying that notions such as dpi, ppi, number of pixels, and bit depth are all means of measuring resolution but from different perspectives? I'll jump back in for a moment. Resolution is being used in the sense of being able to separate something into parts. DPI, PPI,# of pixels are all ways of measuring how a scanner can separate an image into multiple(Ok, thousands or millions of parts) in space. Bit depth will determine how finely a color can be described as different shades of R, G, or B. Or how many shades of R,G, or B there are to describe the color at any individual pixel. As far as the rest of the argument - be careful what you take from it. There is just too much arguing and misinformation flying around as fact. Add to that a good dose of arrogance and asocial behavior, and a real discussion just doesn't seem to be happening. Jon -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Anthony Atkielski Sent: Tuesday, June 11, 2002 3:11 AM To: [EMAIL PROTECTED] Subject: [filmscanners] Re: Density vs Dynamic range Resolution can refer both to the ability to distinguish between different intensities and the ability to distinguish between spatially separated details. It can be used to refer to the distinctions between different hues or saturation levels, too. It just means how much or how many differences can be seen or rendered in some aspect of the image. - Original Message - From: Laurie Solomon [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Tuesday, June 11, 2002 06:34 Subject: [filmscanners] RE: Density vs Dynamic range I am not going to get into this highly technical discussion where I do not belong as an active participant; however, I do have a question. When you say, Resolution here is the number of discrete shades of R, G or B, are we using the same term, resolution, or using the term in the same way as when we speak of resolution in terms of ppi, dpi, line pairs, or number of pixels? If so, I am confused since I did not think that this really had anything to do with the number of discrete shades of R,G, or B but with the number of R,G, and/or B pixels that there were regardless of the shade they portrayed. I further understood the number of discrete shades to be represented by bit depth not resolution. If the term, resolution, is not designated the same thing as indicated by ppi, dpi, line pairs, and numbers of pixels but is being used differently or to designate something entirely different then knowing this is the case would reduce my confusion and clarify the comments for this layman. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Jonathan King Sent: Monday, June 10, 2002 10:45 AM To: [EMAIL PROTECTED] Subject: [filmscanners] Re: Density vs Dynamic range Ok, I bitten my tongue long enough. It hurts! On Mon, 10 Jun 2002 10:32:30 -0400, Austin Franklin wrote: However my point is that if you can reduce the noise level then you can increase the number of steps (by halving the step size) with real benefit, but without altering the range. Hi Peter, Correct, but that INCREASES the dynamic range. No it doesn't. You are confusing dynamic range and resolution. Doubling the number of steps halving the step size will keep the same dynamic range, but it will double the resolution. Resolution here is the number of discrete shades of R, G or B. Peter's point is that if the noise of the system is greater than the step size, decreasing the step size will just digitize noise - Not Good, unless you play with digital processing techniques, as alluded to. My principle argument was that a 5000:1 ratio does not specifically define that 5000 steps are requires Well, yes it does...that's what it means, with respect to what we are talking about. Go download a few linear CCD specs (or if you want, I can mail you some), and you'll see they talk about it in exactly the same way I do. Try this one, unless there is a better example. It looks like a nice CCD for a 4000dpi, 120 film scanner? http://www.kodak.com/US/plugins/acrobat/en/digital/ccd/kli8023Long.pdf FYI Kodak defines dynamic range pretty much the way engineering schools I've attended in the U.S., and apparently Ireland, do: Max. Output level divided by the dark noise level. Just a quick question - do CCDs really use a +/- voltage swing? I'd have thought that would have introduce noise problems around 0. It looks like the Kodak chip uses only positive voltages, but the output has a DC offset that the buffer amplifier and A/D have to deal with. If you want to split technical hairs, please at least be willing to state and consistently use terms. First Nyquist, and now this. It has the appearance of trying to
[filmscanners] Re: Density vs Dynamic range
Austin and Peter, I don't know which of you wrote this quote below, but it threw a big light bulb on above my head as to where part of the confusion comes from. If either of you really thinks this then it must be a complicated business to get into bed at night! ... This post has 3 sections, headings are: RANGE - discusses the confusion about range DYNAMIC - discusses the confusion about what dynamic means SCANNERS - applies dynamic range terminology and discusses the relationship between density and dynamic range. 1) RANGE *** At 03:06 12/06/02, you wrote: However my point is that if you can reduce the noise level then you can increase the number of steps (by halving the step size) with real benefit, but **without altering the range**. Correct, but that INCREASES the dynamic range. The asterisks are mine to draw attention to the problem. Here goes! Big breath... Put some numbers to the above. Let's say max signal is 1000mV and noise (or min signal) is 10mV at first. Then you reduce the noise level by half. So min is now 5mV. OK, so now use the plain English language definition of a range. In the first case, the RANGE of the usable / measurable / instrumentable signal is 10mV to 1000mV, or 100 to 1, or 40dB (volts remember, so 20log, not 10log). In the second case the RANGE of the signal is 5mV to 1000mV, or 200 to 1, or 46dB. Do you see? The plain english RANGE of the signal you are dealing with has changed from 40dB to 46dB. You HAVE altered the range. Why do you say in the quote without altering the range? The range is NOT zero to 1000mV, it never was, and never will be. It is 10mV to 1000mv, then 5mV to 1000mV. The range changes when you change the noise level, that is why you would change the noise level, to increase the range. And look! The calculation for plain english RANGE is the same as the calculation of DYNAMIC RANGE! That is because they are the same thing here. The DR is, as I have said many times, a RANGE. It is not something else, it is a RANGE. Look at the definitions that you quote, it is a range. It is usually measured as a ratio, and usually quoted in dB. It is not a number of levels, or anything else, it is a range. It IMPLIES a number of levels, but it is NOT a number of levels, it is a range. The thinking that leads you to state that by changing the noise level you don't change the range is at the heart of this problem. It does change the range, and it must. And the definition of DR is no different from the definition of plain english range. You seem to have laid an unnecessary layer of additional complexity over all this, and the result is total confusion. I can see WHY you might like to do this, but I don't see how it is useful, and it is at variance with other usage. Here is what you (Austin) said in another response to me: Surely, you can understand that you can have two exact same ranges, with different noise? That can't be hard to understand? No I don't understand that because I most explicitly don't agree. By DEFINITION of the most basic kind, the range we are discussing is from the smallest (noise) to the largest. The RANGE we are discussing is noise to max signal. Change the noise and you change the range. Zero does not exist, because it is not measurable or includable and we are not discussing it. The whole point of discussing the range is to specify the smallest signal and largest signal, it is NOT to choose two arbitrary points inside or outside those figures. The RANGE is the distance between the smallest signal and the largest signal. It is NOT measured from somewhere smaller than smallest signal, or zero or anywhere else. Zero by definition is not in the range of (AC) signals we are taking about - because of noise. Noise not only always exists, it is at the heart of what we are discussing. I repeat - zero does not exist. That is usually the whole point of discussing signal ranges, to see how close we can get our noise to zero. The upper limit is arbitrary and depends on gain, but this arbitrariness is neutralised by stating the RANGE as a ratio. Look Austin - we are discussing a situation in which we are trying to do something intelligent with a smallest measurable signal, and a largest measurable signal. So we use the concept of the RANGE. The range is the difference (or ratio if you want, it doesn't matter) between these two. It is not complicated, it is very very simple, and it is NOT ambiguous. It is NOT something else, and it is NOT up to you to specify arbitrary end points to some range and still expect that so-defined range to have any meaning. If you DO specify arbitrary end points, then you have thrown away the basic premise of your SIGNAL RANGE and you need to invent something else to get it back again. I think you do this and you call your newly defined range the Dynamic Range. But you DON'T need to do this. The actual range is inherent and unambiguous. Why do you
