filmscanners: Downsampling vs averaging RE: Film Scanners and what they see.
Wait a minute, I always thought that down sampling consisted of some kind of averaging (of samples). I thought bicubic and bilinear and such terms could as well be related to down sampling as they could to upsampling. Now I wonder: how does downsampling work? Does it exist of sampling only one of the pixels in the previous larger image for each pixel in the new image? It more or less explains why I have some grainy images that retain a lot of their graininess when downsampled. But why is downsampling often called better than downsizing? Thank you all in advance, Jerry -Original Message- From: Shough, Dean [SMTP:[EMAIL PROTECTED]] Sent: Wednesday, December 06, 2000 4:38 PM To: '[EMAIL PROTECTED]' Subject: RE: filmscanners: RE: Film Scanners and what they see. [cut] I expect you are right except perhaps for the Epson 1200 and 1600 series scanners. I am not sure if they use a custom CCD with smaller pixels or if they are micro-stepping with an ordinary 600 and 800 dpi array. But, now that I think about it, if you use a scanner at 1/2 or 1/4 of its full resolution, then the pixel size remains the same but the Nyquist limit is much lower. Sounds like a recipe for alaising and another good reason to always scan at higher resolution and average down (not down sample). [cut]
Re: filmscanners: Saving Scans
David, I can't stress enough the need to create and organise folders and file names. I stores the images from my digital camera in the form of... 01-Garage,jpg 02-Cat.jpg et cetera This method does have the upper limit of 99 images, so if you're going to go above that on a regular basis, then add another leading zero to give a name of... 001-Garage.jpg I also use this method for Negs Slides, taking the number from the film frame. I've taken this one step further with my Directories/Folders, the method being... DigitalCamera 1999 A-January B-February . L-December 2000 A-January ... and so on Putting the letter in front of the month keeps them in chronological order aswell so that April does not appear at the top of the list. You could of course use 01-January -to- 12-December to achieve the same effect. Regards Chris McBrien. - Original Message - From: "David" [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Wednesday, December 06, 2000 9:51 PM Subject: filmscanners: Saving Scans Hi, When I save to disc, scans from my filmscanner, I want to be able to save in the same order as the original slides were processed. Numbering them 1 to 36 in order, but windows only saves numbers randomly or in blocks of tens, twenties and so on. Can anyone help me so that my new digital archive can then resemble my original one. David. [EMAIL PROTECTED]
RE: filmscanners: 4x5 budget flatbed scanners - opinions
My wallet is recommending I look at the UMAX 3450 since its only $179 CDN (about $110 USD) I am looking for something to 'proof' my 4x5 - anything I really like I can have enlarged normally, the rest I can print out. regards Dave
Re: filmscanners: Polaroid Sprintscan 120?
David, I've seen an add in Canada reducing the price of the Sprintscan 4000 by $500.00 Cdn to $1799.00. Could you tell me what is shipped with the 4000, i.e does it come with a SCSI adapter ? Thank you Dale http://albums.photopoint.com/j/AlbumList?u=10024 "If you aren't the lead dog the scenery never changes" - Original Message - From: "Hemingway, David J" [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Thursday, December 07, 2000 1:28 AM Subject: RE: filmscanners: Polaroid Sprintscan 120? Jonathan, The scheduled release for the SS120 is mid Janurary. The actual release should be 1/15 through 2/15 depending on how fast we can tie up all the loose ends. The MSRP will be $3995 with an expected street price of around $3500. I am sure they will be on allocation initially so the initial street price will probably be higher. David Hemingway Polaroid Corporation -Original Message- From: Jonathan Ross [mailto:[EMAIL PROTECTED]] Sent: Wednesday, December 06, 2000 8:26 PM To: [EMAIL PROTECTED] Subject: filmscanners: Polaroid Sprintscan 120? Anyone know the availability and pricing of the sprintscan 120? It looks like a great scanner. I'm wondering if I should wait for it. Thanks, -Jonathan
RE: filmscanners: Downsampling vs averaging RE: Film Scanners and what they see.
I always thought that down sampling consisted of some kind of averaging (of samples). It SHOULD work that way, if the system (hardware/firmware/driver) is designed properly. But, just as a note, when doing a pre-scan, I assure you it doesn't do it at full resolution...obviously, or it wouldn't be so much faster... How to tell, possibly, is see how long the scan takes... Scan at the optical resolution of the scanner, then scan at 1/2 the optical resolution...see if it takes less time. Providing the data transfer over the scanner interface to the computer doesn't interfere with the test...I'd suggest scanning at line art or something that really lowers the data rate, and then compare the times. An interesting test I'll try on my scanner when I get the time... Another fly in the ointment is if the downsampling is done in the driver instead of the scanner... So many variables ;-/ But, now that I think about it, if you use a scanner at 1/2 or 1/4 of its full resolution, then the pixel size remains the same but the Nyquist limit is much lower. Sounds like a recipe for alaising and another good reason to always scan at higher resolution and average down (not down sample).
RE: filmscanners: Downsampling vs averaging RE: Film Scanners an d what they see.
I always thought that down sampling consisted of some kind of averaging (of samples). I thought bicubic and bilinear and such terms could as well be related to down sampling as they could to upsampling. Now I wonder: how does downsampling work? Does it exist of sampling only one of the pixels in the previous larger image for each pixel in the new image? It more or less explains why I have some grainy images that retain a lot of their graininess when downsampled. But why is downsampling often called better than downsizing? Thank you all in advance, Jerry -Original Message- From: Shough, Dean [SMTP:[EMAIL PROTECTED]] Sent: Wednesday, December 06, 2000 4:38 PM To: '[EMAIL PROTECTED]' Subject:RE: filmscanners: RE: Film Scanners and what they see. [cut] I expect you are right except perhaps for the Epson 1200 and 1600 series scanners. I am not sure if they use a custom CCD with smaller pixels or if they are micro-stepping with an ordinary 600 and 800 dpi array. But, now that I think about it, if you use a scanner at 1/2 or 1/4 of its full resolution, then the pixel size remains the same but the Nyquist limit is much lower. Sounds like a recipe for alaising and another good reason to always scan at higher resolution and average down (not down sample). [cut] I created some test files so everyone could see what I am talking about. This first image shows a section of a 512 by 512 pixel zone plate. ...OLE_Obj... The original file is symmetric about the bulls eye. The fringes seen in the image increase in frequency as one goes from the center to the edge of the image. The edge of the zone plate is exactly at the Nyquist frequency. Anything in the image outside the inscribed circle is alaised (In the original image, of which only a small section is shown above. If I reduce the size of the image by a factor of 4 in both directions using Photoshop's bicubic interpolation, I get: ...OLE_Obj... This is very similar to what a 128 by 128 pixel scanner would see when looking at the above image. Because of the averaging effect, the bulls eye pattern fades away about 1/4 o the way out from the center. Some slight modulation is still apparent out at the edge o the image - this is alaised information whose magnitude has been greatly reduced due to the low pass filtering of the pixels finite size. If I reduce the size by using Photoshop's nearest neighbor algorithm (the same as down sampling) I get: ...OLE_Obj... Outside the central 1/4 of the image, the strongly alaised image no longer bears any resemblance to the correct image. Further more, any filtering I apply to this image will not produce correct image - not even close. You could say that this alaised image is sharper than the non-alaised image, but I don't think anyone interested in obtaining an accurate image would like it. In a real image, the same type of effects will take place, although not nearly as dramatic. There are two reasons for this: 1) No real scanner is going to be able radically alias the image to the extent shown here. Unless of course you tell the scanner to do a low resolution scan and the scanner uses down sampling. 2) No real image will have such strong and regular features above the Nyquist limit. I hope that I made the images small enough to not trip the email filters yet large enough to demonstrate the point. Dean Shough [EMAIL PROTECTED]
Re: filmscanners: Saving Scans
David, you filenames might also appear to be a little random when you initially write the name or move a file from one folder to another. To clear this up just run Windows Explorer and view a folder that has your images in it and click on Name at the top. This will re-aarange your filenames in alphabetical or reverse alphabetical order. Also clicking on the headers of the other columns will alter the apparent order of the file names. Chris McBrien - Original Message - From: "David" [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Wednesday, December 06, 2000 9:51 PM Subject: filmscanners: Saving Scans Hi, When I save to disc, scans from my filmscanner, I want to be able to save in the same order as the original slides were processed. Numbering them 1 to 36 in order, but windows only saves numbers randomly or in blocks of tens, twenties and so on. Can anyone help me so that my new digital archive can then resemble my original one. David. [EMAIL PROTECTED]
Re: filmscanners: RE: Film Scanners and what they see.
Austin Franklin wrote: The oversampling business in CD players is mostly a method to save as much as maybe a dime in their production costs to reduce the cost of the analog output reconstruction filter. Not quite. There is no oversampling in a CD player, it is interpolation. And it's not primarily money, it's quality. Output filters of the frequencies involved in CD reproduction, without using interpolation, end up being quite complicated, and their designs cause incoherent output. It is far easier to get coherent output from a higher frequency 1st order filter. My reference to "oversampling business" referred to what was being printed on the boxes and front covers of CD players. Further, at least at first,the "oversampling" CD players were low end units -- talking in real-world terms, they did it to save the dime (assuming sub-penny made in China parts). Yes a filter with steep skirts could tend to produce group-delay effects at the higher frequencies, but the only people who'd dare say they could tell the difference would be folk who wouldn't have a digital audio system to begin with (only mild sarcasm, mostly true :-). As to complexity, only in terms of the number of parts. Such filter designs are almost cookbook and are trivial to model in spice (a computer program for those who don't know) variants. There undoubtedly are programs that just spit out the circuit and values with parameters put in -- but that's not my field so it isn't what I use (I uses "spice" only rarely, my simulators are mostly digital-oriented). So I agree with all you say except for the leading "Not quite". CD players are mass-market consumer devices. Everything is to squeeze the last cent out of the production cost, and I mean that literally. Unfortunately, this also applies to scanners to film scanners to some extent, or strongly will be when they become US$ 49 USB devices sold at the local high volume sell-everything stores. Mike K.
RE: filmscanners: Polaroid Sprintscan 120?
Dale, To be sure I will contact the Canadian sales manager. Either he or I will get back to you soon. David -Original Message- From: Dale Gail [mailto:[EMAIL PROTECTED]] Sent: Thursday, December 07, 2000 7:23 AM To: [EMAIL PROTECTED] Subject: Re: filmscanners: Polaroid Sprintscan 120? David, I've seen an add in Canada reducing the price of the Sprintscan 4000 by $500.00 Cdn to $1799.00. Could you tell me what is shipped with the 4000, i.e does it come with a SCSI adapter ? Thank you Dale http://albums.photopoint.com/j/AlbumList?u=10024 "If you aren't the lead dog the scenery never changes" - Original Message - From: "Hemingway, David J" [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Thursday, December 07, 2000 1:28 AM Subject: RE: filmscanners: Polaroid Sprintscan 120? Jonathan, The scheduled release for the SS120 is mid Janurary. The actual release should be 1/15 through 2/15 depending on how fast we can tie up all the loose ends. The MSRP will be $3995 with an expected street price of around $3500. I am sure they will be on allocation initially so the initial street price will probably be higher. David Hemingway Polaroid Corporation -Original Message- From: Jonathan Ross [mailto:[EMAIL PROTECTED]] Sent: Wednesday, December 06, 2000 8:26 PM To: [EMAIL PROTECTED] Subject: filmscanners: Polaroid Sprintscan 120? Anyone know the availability and pricing of the sprintscan 120? It looks like a great scanner. I'm wondering if I should wait for it. Thanks, -Jonathan
Re: filmscanners: Saving Scans
Save them as 2 digit numbers. 01, 02 03, etc Yes, this is what I do : assign each film a reference number (which relates to a database record), and then number each frame with the frame number on the film rebate. eg 1234_03 Regards Tony Sleep http://www.halftone.co.uk - Online portfolio exhibit; + film scanner info comparisons
Re: filmscanners: RE: cd storage
In summer '99, for the total eclipse, I experimented with viewing the sun through CDs, and found two together gave comfortable viewing. *That* would have made a nice photo :-) Regards Tony Sleep http://www.halftone.co.uk - Online portfolio exhibit; + film scanner info comparisons
RE: filmscanners: RE: Film Scanners and what they see.
My point was - I wonder whether digital interpolation would be useful in a scanner design to smooth the output? That's what anti-aliasing filters in image editing software do, interpolate pixels to achieve smoothing. Regards Tony Sleep http://www.halftone.co.uk - Online portfolio exhibit; + film scanner info comparisons
RE: filmscanners: RE: Film Scanners and what they see.
Further, at least at first,the "oversampling" CD players were low end units That's not quite true, they were mid range units, and it was because the initial interpolation filters were quite bad, and were only 2x to 4x, and certainly did not meet the audio quality that was achievable without them. As to complexity, only in terms of the number of parts. Such filter designs are almost cookbook and are trivial to model in spice (a computer program for those who don't know) variants. Have YOU ever designed an output filter for a high end audio D/A not using an interpolation filter? I've been designing (and have a very high end analog engineer who designs) them for 20 years, and they are NOT trivial nor are they cookbook. They are in fact an art, and not many people can design them well. CD players are mass-market consumer devices. Better tell that to Mark Levinson... Have you ever seen, heard, or looked at the guts of an ML39? Unfortunately, this also applies to scanners to film scanners to some extent... Not to any scanner I'm interested in. Again, better tell that to Scitex, Imacon and Epson (about their professional series)
RE: filmscanners: Downsampling vs averaging RE: Film Scanners an d what they see.
Let me try this again, this time directly linking to the files instead of cutting and pasting... -- I always thought that down sampling consisted of some kind of averaging (of samples). I thought bicubic and bilinear and such terms could as well be related to down sampling as they could to upsampling. Now I wonder: how does downsampling work? Does it exist of sampling only one of the pixels in the previous larger image for each pixel in the new image? It more or less explains why I have some grainy images that retain a lot of their graininess when downsampled. But why is downsampling often called better than downsizing? Thank you all in advance, Jerry -Original Message- From: Shough, Dean [SMTP:[EMAIL PROTECTED]] Sent: Wednesday, December 06, 2000 4:38 PM To: '[EMAIL PROTECTED]' Subject: RE: filmscanners: RE: Film Scanners and what they see. [cut] I expect you are right except perhaps for the Epson 1200 and 1600 series scanners. I am not sure if they use a custom CCD with smaller pixels or if they are micro-stepping with an ordinary 600 and 800 dpi array. But, now that I think about it, if you use a scanner at 1/2 or 1/4 of its full resolution, then the pixel size remains the same but the Nyquist limit is much lower. Sounds like a recipe for alaising and another good reason to always scan at higher resolution and average down (not down sample). [cut] I created some test files so everyone could see what I am talking about. This first image shows a section of a 512 by 512 pixel zone plate. Zone256crop.jpeg The original file is symmetric about the bulls eye. The fringes seen in the image increase in frequency as one goes from the center to the edge of the image. The edge of the zone plate is exactly at the Nyquist frequency. Anything in the image outside the inscribed circle is alaised (In the original image, of which only a small section is shown above. If I reduce the size of the image by a factor of 4 in both directions using Photoshop's bicubic interpolation, I get: Zone128bicubic.jpeg This is very similar to what a 128 by 128 pixel scanner would see when looking at the above image. Because of the averaging effect, the bulls eye pattern fades away about 1/4 o the way out from the center. Some slight modulation is still apparent out at the edge o the image - this is alaised information whose magnitude has been greatly reduced due to the low pass filtering of the pixels finite size. If I reduce the size by using Photoshop's nearest neighbor algorithm (the same as down sampling) I get: Zone128nearestNeighbor.jpeg Outside the central 1/4 of the image, the strongly alaised image no longer bears any resemblance to the correct image. Further more, any filtering I apply to this image will not produce correct image - not even close. You could say that this alaised image is sharper than the non-alaised image, but I don't think anyone interested in obtaining an accurate image would like it. In a real image, the same type of effects will take place, although not nearly as dramatic. There are two reasons for this: 1) No real scanner is going to be able radically alias the image to the extent shown here. Unless of course you tell the scanner to do a low resolution scan and the scanner uses down sampling. 2) No real image will have such strong and regular features above the Nyquist limit. I hope that I made the images small enough to not trip the email filters yet large enough to demonstrate the point. Dean Shough [EMAIL PROTECTED] Zone256crop.jpeg Zone128bicubic.jpeg Zone128nearestNeighbor.jpeg
filmscanners: re saving scans
Thanks guys, I did'nt think it could be so easy. I think I can say that now I have learnt everything about scanning. From which scanner and printer I needed and to the knowledge to get results, from this list. Thanks again, David.
Re: filmscanners: RE: Film Scanners and what they see.
Rob Geraghty wrote: When I was reading something someone else wrote on this topic I couldn't help wondering about the kind of oversampling used in CD players to filter the output. I wonder if similar technology could be used to smooth the output from a scanner - maybe some scanners already do? Oversampling in a CD player just interpolates points to cheat the nyquist limit. Presumably in some way this is analogous to what "true fractals" does? I've been steering clear of this thread, but I think this question is clear cut enough to avoid further confusion. Probably famous last words time, - but here goes. Oversampling in audio is a hardware implemented function, which is really only of any worth when it's applied at the recording stage. The primary use is to make the 'brick wall' low-pass filter more effective (and cheaper to make) prior to the A to D conversion stage. The analogue in scanning would be to sample at a higher rate, ie. more pixels per inch, and then to resample to a lower resolution before taking the image information out of the scanner. That way you'd have manageable file sizes, and hopefully, reduced aliasing artefacts. Any manipulation done after the scan would have to be *much* cleverer than simple interpolation to clean up an already aliased signal. Cleverer than 'Genuine Fractals' even. A researcher at Microsoft (is there nothing they won't stick their clumsy fingers in?) has shown, crudely, how oversampling can be used to reduce aliasing in digital HDTV without increasing the bandwidth to accomodate high sampling rates, or requiring spatial low-pass (or should that be long-pass?) filtering. To get back to applying oversampling to scanners, there are plenty of 10,000 pixel per line linear CCD arrays around. It wouldn't take much to combine an area of 4 samples into one, using a true RMS algorithm. This would mean that the scanner would output only 5,000 dpi, but the brightness level could be much more accurately represented than simple area integration allows. Bi-cubic interpolation of a 16 pixel area would probably be better, but we don't want to get ahead of ourselves, do we? BTW. Does anyone have the details of Kodak's 'accurately fuzzy' optical filter, or does it simply exist in an accurately fuzzy description? Regards, Pete.
RE: filmscanners: RE: Film Scanners and what they see.
Austin wrote: Rob Wrote: Putting a smoothing function into the scanner's own interface would be much simpler from the user perspective. Simpler, yes, but how many people would actually use it? I would for one! Last I checked, I wasn't the only one appalled by the coarse "grain" appearing in scans of negative film. Why would you want to do it... haven't we been talking about increased apparent grain for a couple of years now? How does interpolation increase grain? Er - I thought we were talking about *decreasing* the apparent grain by filtering? Rob Rob Geraghty [EMAIL PROTECTED] http://wordweb.com
Re: filmscanners: Saving Scans
Dieder wrote: i.e. 2000.11.30 0X, 2000.11.30 01, etc etc. Now I realize that you have to choose a separator that is compatible with your OS. I've been using a similar method on the PC but without any punctuation; date in reverse order followed by a film number followed by a frame number viz: "20001201 0101". I still have to find a program to track all the pictures, since a naming convention like that clearly doesn't tell you what's in the picture! Rob Rob Geraghty [EMAIL PROTECTED] http://wordweb.com
RE: filmscanners: RE: Film Scanners and what they see.
Tony wrote: Rob Wrote: My point was - I wonder whether digital interpolation would be useful in a scanner design to smooth the output? That's what anti-aliasing filters in image editing software do, interpolate pixels to achieve smoothing. Sure, but as I pointed out elsewhere: 1) There's people with scanners who don't have Photoshop 2) There's people with scanners and photoshop who don't know how to use Photoshop 3) An anti-aliasing filter in the scanner interface could be made much easier to use, and in the case of a scanner like the LS30 could work with 10bits per channel instead of 8 bits per channel. Do the filter in Photoshop work with 16bit data yet? Rob Rob Geraghty [EMAIL PROTECTED] http://wordweb.com
Re: filmscanners: RE: Film Scanners and what they see.
on 12/7/00 3:51 PM, Rob Geraghty at [EMAIL PROTECTED] wrote: Do the filter in Photoshop work with 16bit data yet? The important ones (Gaussian Blur, Add noise and most importantly Unsharp Mask) sure do in Photoshop 6! Andrew Rodney
RE: RE: filmscanners: RE: Film Scanners and what they see.
Er - I thought we were talking about *decreasing* the apparent grain by filtering? I must have misread the post i replied to...I thought I read INcrease, which made no(t much) sense to me... - Sent using MailStart.com ( http://MailStart.Com/welcome.html ) The FREE way to access your mailbox via any web browser, anywhere!
filmscanners: Avoiding Posterization with Vuescan
I recently had a computer crash and had to re-install just about everything. I also recalibrated my monitor using Photocal and the mc7 sensor. After I did this I opened some bw files in Photoshop and discovered posterization in the very dark areas that I hadn't noticed before. I use Vuescan to scan bw negs on my Sprintscan 4000, and I suspect I need to make some adjustments. What is the best way to begin? The scans that show posterization have extreme ranges of light to dark. Is posterization unavoidable on these types of images? STEPHENJENNINGS P h o t o g r a p h e r Cambridge, MA [EMAIL PROTECTED]
RE: RE: filmscanners: RE: Film Scanners and what they see.
Austin wrote: Er - I thought we were talking about *decreasing* the apparent grain by filtering? I must have misread the post i replied to...I thought I read INcrease, which made no(t much) sense to me... I probably referred to the fact that aliasing in a scanner *increases* the apparent grain. I can undersand you wondering why anyone would want to increase it even more. Rob Rob Geraghty [EMAIL PROTECTED] http://wordweb.com
Re: filmscanners: RE: Film Scanners and what they see.
Pete wrote: Oversampling in audio is a hardware implemented function, which is really only of any worth when it's applied at the recording stage. The primary use is to make the 'brick wall' low-pass filter more effective (and cheaper to make) prior to the A to D conversion stage. Er. Sorry, but the same brick wall low pass filter is also needed after the D/A in a CD player to eliminate aliasing errors on the output, otherwise you could destroy your hifi power amp by feeding it high levels of inaudible frequencies - as well as their harmonics. But this is a scanning list so let's not dwell on it anymore? A researcher at Microsoft has shown, crudely, how oversampling can be used to reduce aliasing in digital HDTV without increasing the bandwidth to accomodate high sampling rates I'd be interested to know how this was done. It wouldn't take much to combine an area of 4 samples into one, using a true RMS algorithm. This would mean that the scanner would output only 5,000 dpi, but the brightness level could be much more accurately represented than simple area integration allows. Unfortunately, the hardware would probably be beyond affordability for most of us. :( Rob Rob Geraghty [EMAIL PROTECTED] http://wordweb.com
