Re: filmscanners: ReSize, ReSample or ReScan ?
Thank you Art for your deep reply. Best regards, Dave Arthur Entlich wrote: > > Common wisdom is that scanning at the highest optical resolution and > then downsampling via a good program provides better results. > > But, I would suggest the obvious, which is try both. There are a few > reasons why I suggest testing (and they are not to be snide). Different > scanners deal with lower than optical res scans differently. Some > always use software to downsample rather than just select spaced sensors > on the CCD, some only use actual sensors data with certain resolutions > (see below for more on this). Further, the type of image alters the > result. Line drawings or images with high contrast edges and fine detail > usually do better to be scanned at native optical resolution and > downsampled in something like Photoshop. But even that needs to be > qualified. As nice as bicubic downsampling is (and it is for most color > images), for some images "closest neighbor" creates a more accurate > result. > > Some images might look better with the scan directly from the scanner > (especially if you scan at a resolution which is an even divisor of the > scanner's native (optical) resolution.) Of course, this depends upon > the scanner firmware/software but a 4000 dpi optical scanner should be > able to produce a 500 dpi scan without using any interpolation, simply > by reading every 8th sensor on the CCD. Asking for a 450 or 550 dpi > scan might force the scanner to do an interpolative scan which might not > be as good as a downsampled scan in photoshop. > > In your case, I honestly believe doing the empirical tests will provide > you with a much better answer than I can. > > Art > > David wrote: > > > > If you want to put a picture in your web with 500 pixels wide, > > what is better? Scan at full 4000 dpi and resample to adjust > > your image at this size (letting PS discard pixels) or scan > > at this size. I suppose the first choice but I am not very > > secure. ;-( > > > > Best regards, > > > > Dave > > > > > > Unofficial Olympus web page > > http://victorian.fortunecity.com/byzantium/656/index.html > > Unofficial Olympus Gallery > > http://www.taiga.ca/~gallery/subpages/irissari/irissari.html > > -- Unofficial Olympus web page http://victorian.fortunecity.com/byzantium/656/index.html Unofficial Olympus Gallery http://www.taiga.ca/~gallery/subpages/irissari/irissari.html
filmscanners: Re: filmscanners: ReSize, ReSample or ReScan ?
Art wrote: >Common wisdom is that scanning at the highest optical resolution and >then downsampling via a good program provides better results. I've found in the past that scanning at a resolution which produces an image on the screen close to the required size means you can get a sharper jpeg for web use than scanning at maximum res and resampling. I suggested as much in this list, but got shouted down. My recent experience has been that resampling always means I have to sharpen afterwards. As Art suggests - try both and see what works for you. Rob Rob Geraghty [EMAIL PROTECTED] http://wordweb.com
Re: filmscanners: ReSize, ReSample or ReScan ?
Common wisdom is that scanning at the highest optical resolution and then downsampling via a good program provides better results. But, I would suggest the obvious, which is try both. There are a few reasons why I suggest testing (and they are not to be snide). Different scanners deal with lower than optical res scans differently. Some always use software to downsample rather than just select spaced sensors on the CCD, some only use actual sensors data with certain resolutions (see below for more on this). Further, the type of image alters the result. Line drawings or images with high contrast edges and fine detail usually do better to be scanned at native optical resolution and downsampled in something like Photoshop. But even that needs to be qualified. As nice as bicubic downsampling is (and it is for most color images), for some images "closest neighbor" creates a more accurate result. Some images might look better with the scan directly from the scanner (especially if you scan at a resolution which is an even divisor of the scanner's native (optical) resolution.) Of course, this depends upon the scanner firmware/software but a 4000 dpi optical scanner should be able to produce a 500 dpi scan without using any interpolation, simply by reading every 8th sensor on the CCD. Asking for a 450 or 550 dpi scan might force the scanner to do an interpolative scan which might not be as good as a downsampled scan in photoshop. In your case, I honestly believe doing the empirical tests will provide you with a much better answer than I can. Art David wrote: > > If you want to put a picture in your web with 500 pixels wide, > what is better? Scan at full 4000 dpi and resample to adjust > your image at this size (letting PS discard pixels) or scan > at this size. I suppose the first choice but I am not very > secure. ;-( > > Best regards, > > Dave > > > Unofficial Olympus web page > http://victorian.fortunecity.com/byzantium/656/index.html > Unofficial Olympus Gallery > http://www.taiga.ca/~gallery/subpages/irissari/irissari.html >
RE: filmscanners: ReSize, ReSample or ReScan ?
Since in reality these are really very different operations, I fail to see first how any comparison between the two is possible at all (apples and oranges) and second what definition and criteria of "destructive" is being used and with respect to what objective. If one rescales without resampling, one changes the effective resolution, is that destructive? If one resamples without rescaling, one changes the actual resolution, is that destructive? If one resamples and rescales, one has changed the actual resolution as well as the size of the image ( usually proportionately) so as to result in the equivalent to what one started with effectively, is that destructive? Is downward resampling more destructive than upward resampling or interpolation? -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Tony Sleep Sent: Monday, September 24, 2001 1:46 AM To: [EMAIL PROTECTED] Subject: Re: filmscanners: ReSize, ReSample or ReScan ? On Fri, 7 Sep 2001 07:01:59 -0500 Gordon Potter ([EMAIL PROTECTED]) wrote: > I have been told resampling is much more destructive to an image > then resizing. You were told wrong. Try it. Regards Tony Sleep http://www.halftone.co.uk - Online portfolio & exhibit; + film scanner info & comparisons
Re: filmscanners: ReSize, ReSample or ReScan - 4Web ?
Hi Dave, If the only use of your picture is a 500 pixel web images, you can do as I do. I've been scanning with the Sprintscan 4000 for over a year and 95% of the time, my intended output is a 450 pixel jpeg. I scan at 1200 ppi so I have a 5 megabyte (approximate) image to work with. I like that file size because it gives me an adequate amount of information to work with. Then I work on the image in Photoshop after archiving the original scan. In general, my work flow goes something like this: Straighten the image Crop out the border created by the slide mount Save As a PSD and archive as the original scan Run whatever processing is necessary Resize to 72 PPI at 450 pixels (long dimension) Add copyright as an active text layer (usually 14 point with Technical font) Save As using the designated "450-" as a prefix Flatten and add a single pixel stroke in a complimentary color that the web page background will be (if the page is white I add a black stroke, if the page is black I add a white stroke) Unsharp mask Save For Web and my resulting file size is approximately 20k to 30k If the page background is to be white, just prior to adding unsharp mask, I open the folder of 450 pixel Photoshop files and do a batch drop shadow in PhotoImpact, saving as PSD's Then finish the operation in Photoshop again. The reason I use PhotoImpact for the drop shadow is because it's much easier and can give a uniform drop shadow in a batch operation and Photoshop can't: http://bermangraphics.com/tips/photoimpactds.htm Larry >If you want to put a picture in your web with 500 pixels wide, >what is better? Scan at full 4000 dpi and resample to adjust >your image at this size (letting PS discard pixels) or scan >at this size. I suppose the first choice but I am not very >secure. *** Larry Berman http://BermanGraphics.com ***
Re: filmscanners: ReSize, ReSample or ReScan ?
If you want to put a picture in your web with 500 pixels wide, what is better? Scan at full 4000 dpi and resample to adjust your image at this size (letting PS discard pixels) or scan at this size. I suppose the first choice but I am not very secure. ;-( Best regards, Dave Unofficial Olympus web page http://victorian.fortunecity.com/byzantium/656/index.html Unofficial Olympus Gallery http://www.taiga.ca/~gallery/subpages/irissari/irissari.html
Re: filmscanners: ReSize, ReSample or ReScan ?
If you define "resizing" to mean that the pixel dimensions don't change (you do that when you uncheck the "resample image" box under Image > Image Size in Photoshop), then resizing within Photoshop will have no affect on the image. A two-inch wide image at 300 ppi looks the same as far as the internal workings of Photoshop are concerned as a 4-inch wide image at 150 ppi. Resampling will either add pixels (up sampling) or remove pixels (down sampling) from the image and therefore will change it. In a message dated 9/23/2001 11:55:53 PM Pacific Daylight Time, [EMAIL PROTECTED] writes: On Fri, 7 Sep 2001 07:01:59 -0500 Gordon Potter ([EMAIL PROTECTED]) wrote: > I have been told resampling is much more destructive to an image > then resizing. You were told wrong. Try it. Regards Tony Sleep
Re: filmscanners: ReSize, ReSample or ReScan ?
On Fri, 7 Sep 2001 07:01:59 -0500 Gordon Potter ([EMAIL PROTECTED]) wrote: > I have been told resampling is much more destructive to an image > then resizing. You were told wrong. Try it. Regards Tony Sleep http://www.halftone.co.uk - Online portfolio & exhibit; + film scanner info & comparisons
RE: filmscanners: ReSize, ReSample or ReScan ?
I wish I could tell you more about the Durst scanner. We tried to convince them that we needed to keep one for testing (most other manufacturers do that for us, but the Sigma costs about 100 times the others). I was very impressed with the people working on the project. I have used Durst enlargers many times and if there is a comparison here, it should be a good product. I've only been able to view the specifications on their website (http://www.like.ca/Durst/Sigma_page.html) and it looks impressive. Reading back over this reply, I realize it is totally vague. I apologize for wasting the bandwidth. If we do get one, I promise I'll report back. Jack Phipps Applied Science Fiction -Original Message- From: Austin Franklin [mailto:[EMAIL PROTECTED]] Sent: Tuesday, September 11, 2001 5:08 PM To: [EMAIL PROTECTED] Subject: RE: filmscanners: ReSize, ReSample or ReScan ? > A very useful test file Dean! I agree! It is a very useful file, as long as you understand the limits of what it tests, and that the results can be quite detached from any actual grayscale image files you may be printing. Jack, I do believe you and I have bantered this very subject about a few months ago ;-) BTW, do you still like that Durst scanner? Perhaps you could give a little write-up on the list here?
RE: filmscanners: ReSize, ReSample or ReScan ?
> A very useful test file Dean! I agree! It is a very useful file, as long as you understand the limits of what it tests, and that the results can be quite detached from any actual grayscale image files you may be printing. Jack, I do believe you and I have bantered this very subject about a few months ago ;-) BTW, do you still like that Durst scanner? Perhaps you could give a little write-up on the list here?
RE: filmscanners: ReSize, ReSample or ReScan ?
> > ... > > The Piezography driver can use (meaning you get > > improved results from) data up to around 720 pixels/inch. > > It really diminishes after 420 though, ... > > Diminishes according to what? ... "normal" viewing distances. Do YOU have Piezography inks and the driver? Have you experimented to see what looks best?
RE: filmscanners: ReSize, ReSample or ReScan ?
A very useful test file Dean! This is an excellent test to check how your printer handles curves or lines that are not horizontal or vertical. On my Epson 9000 I've found that I don't get the artifacts at multiples of 180 (including 45, 90, 180 and 360). There is no improvement by sending a file higher than 360 even though it is rated at 720 by 1440. For most of my work (printing images 11 by 14 and larger), my personal favorite is 240 dpi which gives good results on our old Epson 3000 but not on the 9000. On the Epson 9000 my final step in printing (after I have finished all editing and color corrections) I upsize from 240 to 360 using a bicubic algorithm in an image editor instead of relying on an apparently crude nearest neighbor method in the printer. The results on most images is noticeable whenever there are curves or fine lines off of horizontal or vertical. BTW, these tests are based on using the Epson print driver inside of Photoshop to drive the Epson 9000, not the external RIP. Your results may vary. Jack Phipps Applied Science Fiction -Original Message- From: Shough, Dean [mailto:[EMAIL PROTECTED]] Sent: Monday, September 10, 2001 9:44 AM To: '[EMAIL PROTECTED]' Subject: RE: filmscanners: ReSize, ReSample or ReScan ? Here is the pdf file that I created that will test your print driver and see what it does at various resolutions. Make sure that you do not allow Acrobat to shrink oversize pages or to expand small pages. <> This file prints out the same image at various resolutions ranging from 239 dpi up to 2400 dpi. The image contains slanted, one pixel wide lines, both black on white and white on black. Sorry, I do not remember who first posted the basic image with the suggestion to print it at various resolutions - all I did was to combined the various resolutions into one pdf file. When I print the file on either an Alps MD5000 or a couple of different HP laser printers, only the 300 dpi image prints correctly. All other images have been resampled. I would be interested in the results with other printers, especially the Epsons.
RE: filmscanners: ReSize, ReSample or ReScan ?
Austin writes ... > ... > The Piezography driver can use (meaning you get > improved results from) data up to around 720 pixels/inch. > It really diminishes after 420 though, ... Diminishes according to what? ... getting out your lupe??? Are you ever going to convince us you can "see" the difference between 2 black pixels spaced 0.0067" and 0.0048 inches apart??? Put these dot pairs on paper, ... hold it 10" away, and then tell us you can "see" the white space between. All I said was ... if you put criteria in accordance with what average people can "see" on you image resolutions, then there isn't much point in pushing beyond 300ppi. shAf :o)
RE: filmscanners: ReSize, ReSample or ReScan ?
> How did you access the PhotoDisk TIFF test file.? > It looks like they have moved it since I originally downloaded it. I went up one level from the URL I posted and now find it in ftp://ftp.photodisc.com/Tech/PDTarget . The original 47 MB TIFF file seems to be gone.
RE: filmscanners: ReSize, ReSample or ReScan ?
For the record, I just printed Dean's test on an Epson 1270 (the old version of the 1290, with 1440 dpi). Used EPP, 1440 dpi, highest quality settings. Out of curiosity, I'll mention that the white lines in black were only barely visible in the top 3 resolutions (239, 240 and 241) - they were completely lost in the rest. Needless to say I don't use Postscript, and maybe that is also why the font used for the res numbers looks fat and horrible (on screen as well as on the print)..? Anyway, just using the criteria of looking for variations in line widths (ie adjacent lines loking fatter or thinner), there seem to be 2 'sweet spots', at 240 dpi and 360 dpi. In practice however, I would agree with other comments that there is little difference when printing 'real' images, once over 200 dpi. I had pretty well settled on 240 dpi as being a nice balance between huge file sizes and good looking prints. I can just pick the difference between 240 and 300+ dpi, but at normal viewing distances it is irrelevant. Your eyesight, fussiness and mileage may vary of course.. :) mark t Ps - Who is about to sign off, because of the traffic generated by the 'aa bait'. I'll come back when it gets back to less 'did so-did not' arguments and more f-s topics. Sincere thanks to the many excellent contributors, both pro and beginner who largely remain on-topic, eg Tony, Art, Rob, Julian, Steve, Dean, Lawrence, Cary, rafe, Mikael (and others who I apologise for not listing but you know who you are). Bye.
RE: filmscanners: ReSize, ReSample or ReScan ?
How did you access the PhotoDisk TIFF test file.? -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Shough, Dean Sent: Monday, September 10, 2001 3:50 PM To: '[EMAIL PROTECTED]' Subject: RE: filmscanners: ReSize, ReSample or ReScan ? > Don't buy into this "magic resolution" claim. Just because a particular > pattern (that has nothing to do with the variety of real images you will > be > printing) prints "better" at a particular DPI does not mean there is a > universal "magic resolution" for every/other image(s). > > The image that was "posted" only has black and white lines. Again, hardly > indicative of a normal photographic image. Personally, I believe this is > a > very flawed test, and any conclusions drawn from it are only valid for > THAT > very image, and are erroneous for any real photographic image. > I believe that in practice you are correct. I created a similar test file using a real image (a small piece of the 47 MB PhotoDisc TIFF test file from ftp://ftp.photodisc.com/Tech/Target/ ) and detected very little difference between the various images. It was only when the image had regular, repeating patterns in it that it became obvious that the print driver was doing some sort of simple sampling. I am not surprised that the effect is not visible with real images as most real images do not have much content at the higher frequencies. The line test I posted shows the sampling effect most clearly. A zone plate (grayscale, concentric circles with various frequencies) test shows the effects of sampling, but it is not nearly as obvious. The real image only showed the effects where the original image contains high contrast, high spatial frequency, repeating patterns. Even then it took very close examination to detect. I expect the effect will appear completely different in any printer that does not use the regular halftoning used in the printers I tested. I am curious how it appears in the Epsons with their error diffusion halftoning. --- Incoming mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.277 / Virus Database: 146 - Release Date: 9/5/01 --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.277 / Virus Database: 146 - Release Date: 9/5/01
RE: filmscanners: ReSize, ReSample or ReScan ?
> Modern printers are definitely approaching "fine" resolutions. > If you put > criteria like is common to "fine" B/W prints on today's printers > ... say, 7 > lines/mm, ... which equates to ~180 pixel pairs per inch, ... then you > realize there isn't much point in sending finer than 300 pixels/in > resolutions to your printer. > > shAf :o) Is this blanket misstatement day ;-) That depends on the printer driver. The Piezography driver can use (meaning you get improved results from) data up to around 720 pixels/inch. It really diminishes after 420 though, at least for my images.
RE: filmscanners: ReSize, ReSample or ReScan ?
Gordon writes ... > ... I have read in several places (including > this list) that certain printers are "set" for lack of a better > word or optimized to certain value of DPI. ... Modern printers are definitely approaching "fine" resolutions. If you put criteria like is common to "fine" B/W prints on today's printers ... say, 7 lines/mm, ... which equates to ~180 pixel pairs per inch, ... then you realize there isn't much point in sending finer than 300 pixels/in resolutions to your printer. shAf :o)
RE: filmscanners: ReSize, ReSample or ReScan ?
> Don't buy into this "magic resolution" claim. Just because a particular > pattern (that has nothing to do with the variety of real images you will > be > printing) prints "better" at a particular DPI does not mean there is a > universal "magic resolution" for every/other image(s). > > The image that was "posted" only has black and white lines. Again, hardly > indicative of a normal photographic image. Personally, I believe this is > a > very flawed test, and any conclusions drawn from it are only valid for > THAT > very image, and are erroneous for any real photographic image. > I believe that in practice you are correct. I created a similar test file using a real image (a small piece of the 47 MB PhotoDisc TIFF test file from ftp://ftp.photodisc.com/Tech/Target/ ) and detected very little difference between the various images. It was only when the image had regular, repeating patterns in it that it became obvious that the print driver was doing some sort of simple sampling. I am not surprised that the effect is not visible with real images as most real images do not have much content at the higher frequencies. The line test I posted shows the sampling effect most clearly. A zone plate (grayscale, concentric circles with various frequencies) test shows the effects of sampling, but it is not nearly as obvious. The real image only showed the effects where the original image contains high contrast, high spatial frequency, repeating patterns. Even then it took very close examination to detect. I expect the effect will appear completely different in any printer that does not use the regular halftoning used in the printers I tested. I am curious how it appears in the Epsons with their error diffusion halftoning.
RE: filmscanners: ReSize, ReSample or ReScan ?
> Just how is this chart/print supposed to be interpreted? At first I > thought > all resolutions printed well on my Epson1160 with MIS VM quadtone inks. > Then > I noticed that there are heavy lines scattered about within each > resolution > target, but then I looked at the PDF, and they are there too. However, as > I > change the view magnification in acrobat, their location shifts. As some > of > this appears to be either an optical illusion, or an effect that occurs > within the monitor or the path to the monitor, I have no idea how closely > my > print should match my screen view in this regard. > > If I am just looking for the little line slashes to print without jaggies > (aliasing) then I'd say, on my setup, all targets print excellent. > With the printers that I have tried (1 Alps and 2 different HP laserjets), only the 300 dpi image prints with no variations in linewidth or gaps in the lines. The displayed image seems to show the lines with various intensities and fades to gray before dropping and lines. I presume that this is because of the Postscript interpreter built into Acrobat. The HP printers were postscript but still dropped pieces of the lines.
RE: filmscanners: ReSize, ReSample or ReScan ?
> > Don't buy into this "magic resolution" claim. > > I understand your reasoning. But maybe I did not ask my > question very well. I have read in several places (including > this list) that certain printers are "set" for lack of a better > word or optimized to certain value of DPI. That is not true. The printer it self has a resolution of, say, 720. If you are printing grayscale, you need to have a dither/halftone algorithm turn the image data into discrete dots. The algorithm may or may not use fixed cell sizes, random patterns...and whole slew of techniques...to simulate grayscale. It is more "driver" dependant than printer dependant, and it will also be image type dependant too. > On the surface it seems logical to me that any printer has > certain registrations for its print head. It does, but you are not printing images that are only black or not black...so yes, the resolution of the printhead does play an important role, but as I've stated...there just is no magic DPI for images. > The amount of ink can > be varied, but if in preparing the image I can use color > resolution that essentially equal the printer's registration You can't do that unless you are using no intermediate colors...only printing the exact colors of the ink(s) in the printer. Image files just aren't like that.
RE: filmscanners: ReSize, ReSample or ReScan ?
> you said the "magic resolution for your Alps MD5000 is 300 dpi. > > Two questions, How does one determine the magic resolution of > one's printer? and since I am lazy, what is the magic resolution > of an Epson 1280? > > > Look at my other post in this thread that has a 56 kB pdf file attached. I see it came through (I thought it might be too large), although it probably did dot show up until after your post. Print it out and see for yourself. I don't have an Epson so I can't say what the Epsons do.
RE: filmscanners: ReSize, ReSample or ReScan ?
Austin wrote: > Don't buy into this "magic resolution" claim. I understand your reasoning. But maybe I did not ask my question very well. I have read in several places (including this list) that certain printers are "set" for lack of a better word or optimized to certain value of DPI. For example I have read that the Epson 1280 (my printer) defaults to 720 dpi, so according to one person, the printer has less adjusting or approximating of colors if the image sent to the printer is at 240 dpi (240 = 1/3 of 720). In a pervious life I also used an HP printer and read more then once that that printer worked best at 200 dpi (and worse at 100 or 300 dpi). On the surface it seems logical to me that any printer has certain registrations for its print head. The amount of ink can be varied, but if in preparing the image I can use color resolution that essentially equal the printer's registration all should be more smoothly at locations in the image where big changes in color or contrast occur. (This is my engineering head speaking, so you must consider the source.) __ Gordon Potter <[EMAIL PROTECTED]> Nashville, TN 37215 USA >
RE: filmscanners: ReSize, ReSample or ReScan ?
> By decimation I mean they will throw away extra pixels until the > resolution is 200 dpi. Likewise, if you feed the printer less > than 200 dpi > then the print driver will simply duplicate adjacent pixels until > it has 200 > dpi. The printer driver does not just "throw away 'extra' pixels", nor does it "simply duplicate adjacent pixels". That's silly. It performs the decimation and interpolation with a far more complicated algorithm than you stated.
Re: filmscanners: ReSize, ReSample or ReScan ?
I expect 254dpi is quite common (100dpcm as used by Durst Epsilon) Steve - Original Message - From: "Shough, Dean" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Monday, September 10, 2001 3:44 PM Subject: RE: filmscanners: ReSize, ReSample or ReScan ? > Here is the pdf file that I created that will test your print driver and see > what it does at various resolutions. Make sure that you do not allow > Acrobat to shrink oversize pages or to expand small pages. > > <> > > This file prints out the same image at various resolutions ranging from 239 > dpi up to 2400 dpi. The image contains slanted, one pixel wide lines, both > black on white and white on black. Sorry, I do not remember who first > posted the basic image with the suggestion to print it at various > resolutions - all I did was to combined the various resolutions into one pdf > file. > > When I print the file on either an Alps MD5000 or a couple of different HP > laser printers, only the 300 dpi image prints correctly. All other images > have been resampled. I would be interested in the results with other > printers, especially the Epsons. >
RE: filmscanners: ReSize, ReSample or ReScan ?
> Dean - > > you said the "magic resolution for your Alps MD5000 is 300 dpi. > > Two questions, How does one determine the magic resolution of > one's printer? and since I am lazy, what is the magic resolution > of an Epson 1280? Don't buy into this "magic resolution" claim. Just because a particular pattern (that has nothing to do with the variety of real images you will be printing) prints "better" at a particular DPI does not mean there is a universal "magic resolution" for every/other image(s). The image that was "posted" only has black and white lines. Again, hardly indicative of a normal photographic image. Personally, I believe this is a very flawed test, and any conclusions drawn from it are only valid for THAT very image, and are erroneous for any real photographic image.
Re: filmscanners: ReSize, ReSample or ReScan ?
Shough, Just how is this chart/print supposed to be interpreted? At first I thought all resolutions printed well on my Epson1160 with MIS VM quadtone inks. Then I noticed that there are heavy lines scattered about within each resolution target, but then I looked at the PDF, and they are there too. However, as I change the view magnification in acrobat, their location shifts. As some of this appears to be either an optical illusion, or an effect that occurs within the monitor or the path to the monitor, I have no idea how closely my print should match my screen view in this regard. If I am just looking for the little line slashes to print without jaggies (aliasing) then I'd say, on my setup, all targets print excellent. Todd > Here is the pdf file that I created that will test your print driver and see > what it does at various resolutions. Make sure that you do not allow > Acrobat to shrink oversize pages or to expand small pages. > > <> > > This file prints out the same image at various resolutions ranging from 239 > dpi up to 2400 dpi. The image contains slanted, one pixel wide lines, both > black on white and white on black. Sorry, I do not remember who first > posted the basic image with the suggestion to print it at various > resolutions If I remember correctly, it was Jack Phelps (sp?) of Applied Science Fiction. > - all I did was to combined the various resolutions into one pdf > file. > > When I print the file on either an Alps MD5000 or a couple of different HP > laser printers, only the 300 dpi image prints correctly. All other images > have been resampled. I would be interested in the results with other > printers, especially the Epsons. >
RE: filmscanners: ReSize, ReSample or ReScan ?
Dean - you said the "magic resolution for your Alps MD5000 is 300 dpi. Two questions, How does one determine the magic resolution of one's printer? and since I am lazy, what is the magic resolution of an Epson 1280? __ Gordon Potter <[EMAIL PROTECTED]> Nashville, TN 37215 USA
RE: filmscanners: ReSize, ReSample or ReScan ?
> #1 Resize the scanned pixels so the image is 4 inches by 4 > inches within photoshop keeping the 2900 dots of data from the > original scan. (I am not at all certain how this works, but this > is what I got from reading "A Few Scanning Tips" by Wayne Fulton > and Photoshop 6.0 seems to do it.) > Many (most or even all?) print drivers will take your 2900 / 8 = 363.5 dpi image and perform a quick and dirty decimation to get down to the printers 200 dpi. By decimation I mean they will throw away extra pixels until the resolution is 200 dpi. Likewise, if you feed the printer less than 200 dpi then the print driver will simply duplicate adjacent pixels until it has 200 dpi. Remember, when I say "200 dpi" it is only because that is the example resolution you used. I will send another reply that has an Acrobat file I created that tests this for your printer. For my printer (an Alps MD5000) the magic resolution is 300 dpi. The other post may or may not pass through the list because the size is 56 kB. > > #2 Resample in photoshop to "convert" the 2900 dots of data to > 800 dots of data at 200 dpi which I send to the printer. > > > > This should give the best results - the bi-cubic resampling used by > Photoshop (make sure you have your preferences set to use bi-cubic by > default) is near optimal. I am aware of only one program that uses the > optimal, sinc, resampling - PanoTools at > http://www.fh-furtwangen.de/~dersch/ (closed for the summer). > > > > #3 Stick the slide into the scanner and get the "desired" 800 by > 800 bits of data from the selected portion of the slide. i.e. > somehow use the Twain drivers to get the resolution I want. > > > Should be equivalent to #1 - decimation of pixels to get the right resolution. > > > I recognize in the real world the choices will never be this > clear, but can one generalize that resampling to a *lower* > resolutions is better/worse then resizing under certain > circumstances? > > It seems to me scanner software would not even offer the option > of lower resolution scans if the quality were always better for > resampling and resizing. > > > But it is much easier to brag about scan time. Image quality is much harder to measure.
