Scanning Slides, A Personal Story

Queensland sunset

I had a box of slides. I had to return it to my friend in Geneva. What would I do? Initially, I was just going to get them duplicated. But years passed, my guilt about holding on to the slides grew, and technology advanced. So, I decided to scan the slides, burn them onto CDs and put them on the Web.

It took quite a while to go from the decision to scan the slides to actually doing it. Some of the delay was due to immature software, but some of it was due to just getting educated.

This document is intended to make this process easier for others in the future. It discusses all of the issues involved including obtaining hardware, software, and developing technique. It is aimed at the home tinkerer who is interested in getting up and running. Professionals are invited to laugh and pepper me with advice. It is also geared towards Linuxheads. Windows users are also encouraged to glean knowledge, but they are also encouraged to stop buying Microsoft products.

Hardware

With scanners, you get what you pay for. You can buy print scanners, slide and negative scanners, and scanners that do all three. The first thing to do is go over to Tony Sleep's site and check out the scans that the various scanners produce. If you're running Linux, your choices will be limited to a number of supported scanners. After your visit, you might think I think the choice of cereal at Safeway is limited too.

My buddy Dan Heller, who got me started in this great adventure, uses the Sprintscan 4000, which is the successor to the 35+, which was also really good. He says, "With 4000 dpi, you can print up to 20x30 images and they're as sharp as a tack."

HP Photosmart c5100a

Me, I just want to put pretty pictures on the Web, so versatility and value were my priorities. I chose the HP Photosmart since it does slides, negatives and prints (up to 5x7). It is of surprisingly good quality considering it is one of the lowest priced slide scanners ($300). It is not the best at peering into the shadows though.

Since the USB ports are not yet well supported under Linux, get the SCSI model which you can order directly from HP. Since the SCSI bus dials down to the lowest common denominator, be sure to hang the scanner off of a different SCSI controller than your disks so you do not slow down your disk I/O.

Software

Under Linux, the best choice is SANE. The Debian Linux distribution, at least, has a SANE package. This package contains software that talks to various scanners and a couple of rudimentary frontends. Be sure that you are using at least version 1.0.2 of SANE; I found that the HP backend in previous versions produced very dark images.

Xsane logo

The frontend that I use to drive the scanner is Xsane. Comments about Xsane in this paper are for version 0.71 except as noted.

Another piece of software that I discovered is SCARSE. It is used to calibrate your scanner. However, I find that the auto-adjust feature in Xsane is good enough for most purposes.

GIMP logo

To manipulate the images, I use the GIMP (GNU Image Manipulation Program). This is essentially a Photoshop look-alike. The ImageMagick package is also very, very handy.

If you want to put your raw, high resolutions on CDs, you can use xcdroast. There should be a package for your Linux system.

General Considerations

Barracuda: caught

I generally do not use gloves since the slide mounts are sufficient to allow handling of the slides without fingerprints. However, when I am sorting the slides (like a deck of cards), or when I need to re-center the slide, I wear latex gloves to protect the slides against fingerprints.

I find that even if I'm loading the processor, the scans come out just fine. Once when my space heater clicked on, the scan came out terrible though.

On the other hand, burning a CD requires a quiescent system. I have seen problems when I was doing some crunching. Background Sendmail and Apache processes are OK though.

Xsane Configuration

  1. Turn off Setup->Enhancement options->Autoenhance gamma so that every time you hit the auto-adjust button, you do not have to reset the gamma, which should typically be fixed for a given scanner and monitor combination.
  2. If you have version 0.61 or earlier, turn on Setup->Saving options->Increase filename counter. Otherwise, the filename counter takes effect automatically if the filename includes a `.'.
  3. In the Advanced Options window, I change Exposure Time from Default to 300% since my scans are usually on the dark side.
  4. Set the gamma to your desired value. I crank it up all the way to 3.0, again because my scans are darker than I would like.

Technique

Sun and waves

Preparing for a Batch

  1. If someone has messed up the order of the slides, and you are numbering, rather than naming the images, reorder the slides. Since fingerprints are your enemy, don cotton or latex gloves.
  2. Since dust is your enemy, dust the work area. A swipe of the desk with my shirt sleeve produces a fine clean room.
  3. Blow out the scanner with a can of compressed air.
  4. Blow out brush with can of compressed air.

Scanning a Slide

  1. Remove water spots and fingerprints.

    I am a heathen and simply pant on the slide and then wipe it carefully with a soft cotton handkerchief. This cleans up the fingerprints nicely and has not scratched a slide. There are commercial clean-up products available.

  2. Dust slide with brush.

    While holding the slide vertically, wipe the slide in several downward strokes of a slide cleaning brush to remove or loosen the dust. Tilt the slide towards a window or bright light so that you can see the little spots of dust. Do not press too hard or you may scratch the slide. I sometimes find that this step is optional and that the next step--blasting the slide with air--is sufficient.

  3. Dust slide with air bulb.

    Blast each side of the slide with several blasts from an air bulb to remove any remaining particles of dust. Keep blowing until all of those spots are gone, or you'll be forever in the GIMP touching up the images. You may have to hit some stubborn pieces of dust with the brush again. Repeat until the slide is immaculate.

    Plug for the environment: I very rarely use compressed air for this step because it is almost never necessary, and it is not worth the removal of mountains due to strip mining for the metal and the obliteration of open space or pollution of waterways with empty cans.

  4. Hit Acquire preview in Xsane and scan.
  5. Frame image in the preview window.

    If you are including the entire slide, place the outline just inside the dark area of the slide to ensure that you do not get any ugly black lines at the edges of your image.

  6. Hit the Auto-adjust button.

    This does a pretty decent job of adjusting the colors. Sometimes I will increase or decrease the contrast a notch or two to hide defects in the sampling or enhance the image. If the slide is unusually light or dark, I may adjust the gamma too.

  7. Hit the Start button.

    During this time, you can update your index file, if you have one, or read some email.

  8. Rotate the slide if necessary and view it.

    One can rotate the image in the preview window in version 0.70 or later and view the image with xv.

    Before the rotate feature was available in Xsane, I used the rotate utility in the ImageMagick package. I had created a bash function called prep so I could say:

    prep 270 image.pnm
    
    to rotate the image 270 degrees and view it. While this was running, I removed the slide, and prepped the next slide.

    Most of the time, scans are fine, but do view the scan and make sure there are not any annoying streaks or specks of dust in unfortunate places.

Bill sails the Thai seas

Post-production

This is one area where I still do not have a lot of experience. My current techniques are limited to a couple of tools in the GIMP. However, it appears you can get a lot of mileage out of them.

Run gimp on your image and then bring up the Levels dialog with Image->Colors->Levels. There is a histogram that represents the color intensities in the image. There is typically no values at either end of the extremes. Try the Auto Levels button. If it does not do a good job, cancel and manually move the black and white triangles so that they point at the minimum and maximum values in the histogram respectively. Both Philip Greenspun (see Using Photoshop) and Dan Heller have recommended this action.

Dan goes on to bring up the Image->Colors->Hue-Saturation dialog and increase the saturation to brighten the colors. He may also tweak the hue if color correction is necessary.

Creating a Rough Web Page

After scanning a roll, I create a rough Web page that contains JPEG versions of the raw scans. I wrapped the steps in a bash function called scanstoweb. This function does the following:

  1. Runs xv -vsmap. I click the Update button to generate thumbnail images for quick perusal of the raw scans later. You are correct--this has nothing to do with the creation of the Web page.
  2. Reads a title for the page that will display the JPEGs, and creates a directory to hold the JPEGs.
  3. Converts the raw scans to 350-pixel-wide JPEG images using the convert utility in ImageMagick. This is as wide as you want to get if you are placing two images across the page since horizontal scrolling is to be avoided. Some folks restrict the images to 200 pixels wide.
  4. Creates a Web page for the directory by running mkpage. This Perl script was written by Dan Heller. I limit the number of images per page to 10 in order to keep the download time to under a minute on a 28 kb modem line. That means that each page should have a maximum size of about 200 kB.
  5. Adds width and height attributes to the images with the wwwis script. This helps browsers lay out the pages before the images arrive.

Burning a CD

  1. Fire up xcdroast and configure it in the Setup screen.
    A campfire in the middle of the outback
  2. Click on Master CD.
  3. Click on Master from/to and choose the directory that contains your raw scans.
  4. Click on Set Image-Type and choose Rock-Ridge + Win95/NT unless you have a better idea. Then click on Save as default.
  5. Click on Set ISO-Header and update the Volume-ID and possibly the Application-ID. If you have not filled in this page at all before, you will need to do so now. I filled the fields in as follows:

    Volume-ID:1993-wt-10
    Publisher-ID:Bill Wohler <wohler@newt.com>
    Preparer-ID:Bill Wohler <wohler@.newt.com>
    Application-ID:Bill & Speedy's 1993 Fais-toi Plaisir World Tour

    I update the Volume-ID, which is like a label, for each roll but only update Application-ID, which is like a title, for each group of CDs. Click on Save as default.

  6. Click on Master Image and then Start Master Image
  7. Click on Write Image and then Start Write Image
  8. Click on Verify burned Img and then Start Verify Image.

Problems

I encountered few problems. Fortunately I found workarounds.

Green streaks in image

The first maddening problem was that I kept getting these colored streaks through the image such as those in the image at left. You can see the green streaks in the dancer's magenta cape. By dumb luck I discovered that if I removed all of the other devices from the bus, the streaks went away.

My friend Dan Heller thinks that had these streaks been red, it would have been caused by proximity to the monitor. The solution in this case would have been to remove the scanner and place it in a dark cool place for 24 hours and then reconnect it further away from the monitor. Since I found a simple workaround, which would seem to indicate that the monitor is not at fault, and placing the scanner far away from the monitor would hardly be convenient, I have not tried his advice. But I include it in case it helps someone else.

Smudged photo

Later, I got a panned shot effect in the last fifth of the image. In other words, the pixel values were the same in each column for the last fifth of the image. My hunch is that the slide is slipping inside the scanner. A subsequent scan causes the slide to pop out rather than stay inside, so it has definitely gotten misaligned. This is either a problem with the particular batch of slides I have, which have a slippery plastic housing, or perhaps the scanner is defective and I should return it.

However, I discovered that if I rotate the slides 180 degrees, they scan just fine, as in the good shot below. So, I'm not sweating it.

Good scan

Results

You can see the results of my learning experience in Bill & Speedy's 1993 Fais-toi Plaisir World Tour. Remember that this collection includes all of the slides, not a choice few, and that I have not performed any post-production on the images, other than what was done in Xsane described above.

References

Hardware

In order to get a good objective evaluations of various scanners and issues, Tony Sleep's site is indispensable. There you can sign up for the filmscanners@.halftone.co.uk mailing list.

Although I went directly to HP to purchase my scanner, one store recommended to me was B&H Photo-Video-Pro Audio Homepage. You could also try Shopping.com or Amazon.

Software

The software used on Linux is SANE. There you can sign up for the sane-devel@.mostang.com mailing list. The frontend is Xsane. The SCARSE scanner calibration software may be of use.

Other tools include the GIMP, ImageMagick, xcdroast for putting your raw scans on CDs, wwwis for adding width and height attributes to the images in your Web pages.

Scanning

There are several pages devoted to scanning and scanner and monitor calibration:

Composition

Before you can scan, you have to shoot. Here is a good introduction to photography techniques . The topics in the left gutter are generally arranged from basic to advanced. In particular, the Golden Mean, Rule of the Thirds, Framing, and Cross-Lines are directly related to composition.


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