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#187432 - 03/08/03 05:04 AM File Size / Scan Size / Image Size
Bud Schrader Offline
Wacko

Registered: 12/16/01
Posts: 467
Loc: Lancaster Ohio, U.S.A.
what do all these have in common? I was told my file size wasn't very large for the size of my images posted on another site- Gary said on another photography forum that he likes to scan in his slides at 700 dpi.My slides , I have found out from the lab, are typically scanned at 300-400 dpi.Does this cause a smaller file size? Do all my scans need re-done after I get the ability to scan larger resolution? My scans for the " SW Michigan Winter & Moonset " thread yeilded terrible results, my slides& prints are much better than what I was able to post. Gary, do you still check up on us? Can anyone shed some light on this mystery (to me) ? Help??
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Bud

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#187433 - 03/08/03 05:41 AM Re: File Size / Scan Size / Image Size
Anonymous
Unregistered


Bud, a computer monitor generally displays your pictures at about 72 dpi. but your file size dpi is what a printer is going to print at so a 700 dpi print will have 700 dots per inch on paper, but if you attempt to put a 700 dpi file on the web your monitor is still going to display about 72 dots per inch of actual screen space so a 700 dpi file will display at almost 10x on your screen. so if your files are larger than 100 dpi you will want to resize the file to 75-100 dpi for web display but you will want to keep your original file at a higher dpi for printing purposes.

John, Gary, Dave or Paul or Tim will come along soon and explain it a little better soon.

Mark

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#187434 - 03/08/03 05:57 AM Re: File Size / Scan Size / Image Size
Bud Schrader Offline
Wacko

Registered: 12/16/01
Posts: 467
Loc: Lancaster Ohio, U.S.A.
Thanks, Mark- I'm going to at least get a book at the librart that may help- I just want to be able to do the best job I can with my images, and understand it too! smile
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Bud

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#187435 - 03/08/03 07:16 AM Re: File Size / Scan Size / Image Size
Dave H Online
Saint

Registered: 01/01/70
Posts: 7827
Loc: Kokomo, IN
Bud,

I am far from an expert, but what Mark has said is correct. Gary will scan his slides at several resolutions, depending on how he intends to use the file. When he scans to print big pictures, he will scan at a very high resolution (dpi) so they will look good when enlarged.

You want to scan to the maximum resolution of whatever you are going to do with the picture. As Mark said, computer monitors display at 72dpi, so you should scan at that resolution. For use on a sight such as this, a JPEG with higher compression is also helpful in that it allows the picture to load faster. We have always asked that folks keep the pictures used here to a size on the longest edge to 500 PIXELS, so they don't overrun the sides of the screen. We have also asked that you try and keep the file size to 100Kb max to allow for reasonable load times. Yes, I'm sure you lose a little something at a lower resolution scan but not that much when it is displayed on our 72dpi monitors.

Dave

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#187436 - 03/08/03 08:02 AM Re: File Size / Scan Size / Image Size
mombo Offline
Saint

Registered: 01/01/70
Posts: 7087
Loc: Phoenix, NY
When I scan photos they generally turn out lousy no matter what resolution. Does that mean my scanner's no good?

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#187437 - 03/08/03 02:31 PM Re: File Size / Scan Size / Image Size
Gary Martin Offline
Member

Registered: 07/07/02
Posts: 998
Loc: Kalamazoo, Michigan
Sorry, gang, I've been extremely busy at work this week and haven't been around much. There also hasn't been much on here of late in the way of questions that I've felt I should weigh in on, but here's the answers to the questions you were posing, Bud.

To answer your first question, Bud, scanning at 300 or 400 dpi definitely yields a smaller file size than one scanned at 700 dpi. For comparison, here are the resolutions that I scan at and the corresponding file sizes:

700 dpi about 1.7 Mb
2000 13.7 Mb
4000 55.0 Mb

I use 700 dpi files to post to the web. A typically full frame slide scan at 700 dpi is going to be about 930 pixels wide. That gives me some room to crop down or whatever I want to do and still end up with a file that will allow me to use the full 600 pixel maximum dimension on here. Actually, I normally crop to about 580 pixels and use a 10 pixel wide black border all around the image to dress it up a little. In the process, you're also changing the pitch to 72 dpi for computer screen display, so your 600 pixel wide file posted on here will be a little over 8 inches wide when displayed on a computer monitor.

2000 dpi files are good for images in the 5x7, 6x9 range when you're printing at 300 dpi, which is the standard for custom prints from digital files. I won't go above 6x9 with a 2000 dpi scan.

4000 dpi files are what I use for larger prints, up to 12x18 you don't have to do any interprolation or anything from your starting ~55 Mbyte file. The typical 12x18 is actually around 40 Mbytes so you've got some cropping room.

Beyond that you have a choice of either going to an Imacon professional scanner that can go up to 10,000 dpi, with a price tag of about $16K, or you can use specialized fractal software -- the industry standard right now is probably Genuine Fractals, V2.5 is the current version from Altamira - that can be downloaded from the following site:

http://www.publishingperfection.com/default.asp?mfgId=ALM&src=google+altamira

When you want to generate really LARGE prints via a professional lab, Genuine Fractals is the way to do that. You can enlarge images up to 600% from your starting file without image degradation. The large 30x40 print that I had hanging at the gallery show here in Kalamazoo last fall was done via that route and then professionally printed on a Chromera printer on archival professional photographic paper 30 inches wide. The file size for that print was about 320 Mbytes, which is getting pretty large.

Going back to slides and file size, keep in mind to start that a slide is 24x36 mm full frame and when it's mounted, a little smaller than that because the mount overlaps the image slightly, probably by about 1 mm on each side. There are 25.4 mm/inch, so your side's viewable area in the mount is probably about 1 1/4 inches or so. At let's say 400 dpi, then you've got ~500 pixels of image width if your viewable image area was 1 1/4 inches when scanned. This is going to lead to a displayed image at 72 dpi of about 7 inches wide if you can use all of the width. If you crop at all with your photographic imaging software the resulting image will, of course, be smaller.

If you want to do anything but post your existing scans to the web, Bud, you're going to have to rescan them when you have the ability to scan at higher resolution. Printing a 500 pixel wide scan (400 dpi) at 300 dpi, which is what prints should be done at, is only going to give you a print a little less than 2 inche wide which won't be very satisfying.

The photoprocessing folks that offer scanned slides on CDs typically batch scana them using an autofeeder. The larger the scan you're doing in dpi, the longer it takes to complete each scan. They're not going to generate high quality scans for each and every slide and be able to do enough volume to stay in business. Kodak processing, I think offers a couple of scans of each image at different sizes but to be honest, I never use that service considering what I have sitting at home at my disposal. Typically, a good high res scan at ~4000 dpi would cost you about $10 each from a professional photographic lab. The difference there too is that they're going to make sure that the color of your scan match the original slide. That also doesn't happen with the batch scanned stuff. The batch scanning process will get you close but saturation, color balance, and contrast may still have to be adjusted by you to get it to match the slide.

In terms of going from the scan on your computer screen to the file that you post. OK, here you're going to go from what's usually a TIFF (Tagged Image File Format) or a BMP (Bit MaP) file to a JPEG (Joint Photo Expert Group) file. JPEGs are the preferred format for most web posts. This is an image compression process. You can control the degree of compression as I'm sure you're already aware, Bud. As DaveH noted, they've asked people to keep files <100 KBytes for posting on here to keep down server space consumption. The typical file that I post here starts as a 700 dpi ~1.7 Mbyte BMP file that I downsize to 600 pixels, including a 20 pixel wide frame. When I convert that to a jpeg, I usually end up with a file in the range of about 60 KBytes that I shoot for. That also helps to keep download times for images shorter when people are on a dialup connection.

This is getting a bit long in the tooth Bud and I hope that I've answwered all of your questions. If I haven't let me know and I'll certainly try to do so. Hope this helped.

Gary
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http://www.coastalbeacons.com

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#187438 - 03/08/03 05:30 PM Re: File Size / Scan Size / Image Size
Webmaster Offline
Saint

Registered: 01/01/70
Posts: 13047
Loc: Arizona
Wow, Professor Martin!! Thanks. That answers a LOT of questions I had too!
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Webmaster@LighthouseKeepers.com

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#187439 - 03/08/03 05:33 PM Re: File Size / Scan Size / Image Size
Bud Schrader Offline
Wacko

Registered: 12/16/01
Posts: 467
Loc: Lancaster Ohio, U.S.A.
Gary, and all thanks for the responses. Any info I get will help, I'll take some time, sort through it and see if I have any more questions. Gary, will an epson 2450 yeild enough resolution for 8X10? It's like 2800X3600- Most reviews are very good, I know it's a flatbed, but-----
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Bud

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#187440 - 03/09/03 12:56 AM Re: File Size / Scan Size / Image Size
Gary Martin Offline
Member

Registered: 07/07/02
Posts: 998
Loc: Kalamazoo, Michigan
Professor, John? I haven't been called that in the 14 years since I left academia where I was one! LOL I wasn't trying to write a treatise on the subject but it sorta turned out that way... Glad there was some useful information there for even someone as websavvy as you, John.

Bud, the magic number when you go to print anything is 300 dpi. That's the industry standard. When I have prints made from my files at the prof photo lab that I use, I deliver them to them as 300 dpi TIFF files. It doesn't matter that printers can do 1440 dpi. Professional prints are done at 300 dpi and your eye can't see anything much finer than that anyway. That said, the Epson scanner you're talking about gives you 3600 pixels in the long dimension. That translates to a print that would be 12 inches in that direction without having to do any interpolation (resizing enlargement). So, yep, you could get good 8x10s from that scanner if your image file ends up being a full 2800x3600. That may be limited by your source material, in which case the size of the resulting file dimensions in pixels will be smaller.

Hope that this helps, Bud. If I've still not answered the question, let me know...

Gary
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http://www.coastalbeacons.com

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#187441 - 03/09/03 02:00 AM Re: File Size / Scan Size / Image Size
Torchbearer Offline
Member

Registered: 04/14/00
Posts: 1814
Loc: North Carolina
Wow, that works for me too! I too had some unanswered questions, but no more. Thanks again guys for your help. Hope you don't mind but, I went ahead and copied for my personal files in case I have any questions in the future.

The other Tim

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#187442 - 03/09/03 03:10 AM Re: File Size / Scan Size / Image Size
Gary Martin Offline
Member

Registered: 07/07/02
Posts: 998
Loc: Kalamazoo, Michigan
Help youself, Tim. That's what this forum is for.

Gary
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http://www.coastalbeacons.com

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#187443 - 03/09/03 12:57 PM Re: File Size / Scan Size / Image Size
Bob M Offline
Saint

Registered: 01/01/70
Posts: 12331
Loc: North Attleboro, Mass.
Great info, guys! Many thanks for sharing.

smile Bob smile

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#187444 - 03/09/03 10:32 PM Re: File Size / Scan Size / Image Size
Bud Schrader Offline
Wacko

Registered: 12/16/01
Posts: 467
Loc: Lancaster Ohio, U.S.A.
Gary, thanks for taking the time to go through all that- big help!
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Bud

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#187445 - 03/11/03 03:21 AM Re: File Size / Scan Size / Image Size
mombo Offline
Saint

Registered: 01/01/70
Posts: 7087
Loc: Phoenix, NY
I've read through Gary's first reply here about 5 times trying to see if there's something there even I can understand, lol. Let's see if I got this right. If I want to scan a print or a postcard just to put on the web it will turn out better if I scan it at a higher resolution, do any fixing up, resizing, etc and then change the resolution to 72 dpi instead of just scanning the item at 72 dpi to begin with??????

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#187446 - 03/11/03 04:35 AM Re: File Size / Scan Size / Image Size
Gary Martin Offline
Member

Registered: 07/07/02
Posts: 998
Loc: Kalamazoo, Michigan
Mombo, if you're scanning a print or a post card, you can get away with scanning at lower digital res than I do with a slide. Keep in mind my slide is only about 1 1/4 inches wide, which would only be about 100 pixels if I scanned it at 72 dpi. On the computer, the posted photo done that way would be, well slide-sized! Consequently, I scan at higher digital res so that I've got a file that would be about 500-600 pixels wide when I post it. If your post card is 6" wide to start and you scan at 72 dpi then you've got a 432 pixel wide image to work with. That's the difference. Hope that helps some.

Gary
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http://www.coastalbeacons.com

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#187447 - 03/11/03 03:30 PM Re: File Size / Scan Size / Image Size
WackoPaul Offline
Saint

Registered: 01/01/70
Posts: 8949
Loc: Indy
Mombo remember when you scan printed material you are scanning the dot stucture of that material and the surface of tha material (ie beaded, dust, fingerprints). Some scanners have different settings (filters) when scanning published materials as opposed to an actual photographs that help in those scans...

I use Genuine Fractals (Photoshop Plugin) on just about all of the images that I work with.. It is great for resizing without loss of quality. The Altamira company is now owned by Lizardtech and information on all of their products can be found here..

Lizardtech

I am waiting for them to come out with a version that works with Mac OS X 10.2 (Jaguar), in the meantime my Mac OS 9.2 version works Great!!
_________________________
Onward to The Land of the Midnight Sun!

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#187448 - 03/11/03 04:04 PM Re: File Size / Scan Size / Image Size
mombo Offline
Saint

Registered: 01/01/70
Posts: 7087
Loc: Phoenix, NY
I guess I should play around with my scanner software a bit to see what it's capable of. Lots more than I can understand that's for sure. Nice to hear my problems are probably the extra "junk" on the photos and especially those old cards! Thanks.

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#187449 - 03/14/03 04:25 AM Re: File Size / Scan Size / Image Size
Bud Schrader Offline
Wacko

Registered: 12/16/01
Posts: 467
Loc: Lancaster Ohio, U.S.A.
OK Gary, if I scan at a high resolution and save to a disc, then take the disc to the lab for an 8X10, will the results be as good as if I took the slide to the lab for the same? Or if I scan at high resolution and print directly at that time, what results would be best? This is a moot point as I have neither a scanner or printer,
but--------
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Bud

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#187450 - 03/14/03 04:53 AM Re: File Size / Scan Size / Image Size
Gary Martin Offline
Member

Registered: 07/07/02
Posts: 998
Loc: Kalamazoo, Michigan
At the risk of starting an argument among those with brand preferences, prints coming off of my Epson 2200 printer under a 4X loupe, IMO at least, look as good as prints done from the same file at the professoinal photo lab that I use. I personally swear by Epson printers and wouldn't own another HP, but that's just my opinion. Canon also has a pretty good reputation although I've never owned one of their printers. That said, I can only print to super B paper (13x19) or on roll stuff to 13x44 whereas the lab can do prints to 30x50.

Prints from slides vs. prints from digital files? That's a more interesting question. Some of the new technology, like the Fuji Frontier printer that the lab I help to underwrite uses, allow them to take a slide and generate a print from it via a digital "intermediate" file. The quality of that is excellent and the color fidelity is only a question of how picky the folks running it at the lab are vs. how picky you are. They're excellent.

So, I guess it becomes pretty much a toss up if you're working for a really good slide and a really high quality digital file. Beyond that it becomes a question of the calibration of your computer monitor and how well the printer will translate what you see on the screen onto paper, and how well all of that relates to the source slide. I suppose if all of that sounds like a bunch of handwaving, well... I don't know if any of this helps, Bud, but I tried.

Gary
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http://www.coastalbeacons.com

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#187451 - 03/14/03 09:45 AM Re: File Size / Scan Size / Image Size
Mike Hershberger Offline
Member

Registered: 11/09/02
Posts: 183
Loc: Elkhart, IN
Based on Gary's advice I downloaded and tried the Genuine Fractals plugin. It seemed to work ok once I figured out how to use it, but in comparing it side by side with a standard resize in PSP, the difference was barely noticeable. The fractaled image still looked like it had been resized. Maybe there's something I did wrong, or maybe I was expecting too much out of it.
Any thoughts?
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Mike Hershberger

http://www.harbor-of-refuge.com

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#187452 - 03/15/03 06:11 AM Re: File Size / Scan Size / Image Size
Bud Schrader Offline
Wacko

Registered: 12/16/01
Posts: 467
Loc: Lancaster Ohio, U.S.A.
Thanks, Gary- I guess maybe it's a matter of opinion thing. Yhe lab in Columbus I've started to use has the Frontier, also, and they don't think the scan to disc would be very satisfying- thier opinion,of course. They did a few prints for me and adjusted some dark blue out,(from a slide) a result of early morning sun and polarizer, the print looked OK, but I see a bit of a digital " line " along the roof, so I'm not convinced that process is that much better. That said, I thank you Gary for your help, I hope to get my scanner yet this month so I can start to experiment myself.
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Bud

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#187453 - 03/15/03 07:05 AM Re: File Size / Scan Size / Image Size
Anonymous
Unregistered


After Paul and Gary told me about Genuine Fractals I went ahead and bought the 2.5 version and after figuring it out I have created a number of picture files at various sizes, just a few weeks ago I took 3 files to a professional color lab to see how I did with the whole process of scanning, cleaning up the image and then resizing them for printing. I couldn't be happier with the results, I did 2 pictures in the 4x12 format and had the other enlarged to an 11x14 with great results. Even the color lab people were impressed by the pictures and asked me if they were for a photographic show/display at a local performing arts center (which I was unaware of). So if your planning on making high quality enlargements I would certainly recomend the Genuine Fractals too.

Mark

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