The Scanning Project-7: How a Scanner Works

While this may be purely of academic interest, I thought it would be a good idea to demystify scanner mechanics a bit. Think of a scanner as a potentially high megapixel imaging device that converts image information from film or prints to a digital file. Just as in a digital camera, the image can be manipulated during the conversion process and given certain attributes, such as correction of color and enhancement through contrast and saturation choices.

For those who have not worked with a digital camera a scanner is akin to a copier. But the scanner does not have toner or nozzles to lay down the copied information; it creates digital image information that can be manipulated to mimic the copied image or to enhance or adjust as needed.

This Epson 850V scanner scans both prints and film using a flatbed design. This illustration shows slides in the film holder, which is then placed directly on top of the platen. 

In essence, a scanner contains an RGB sensor, just as in a digital camera that, in flatbeds, sits underneath a glass covering onto which the material is placed. Flatbed scanners have both fixed and movable mirrors and a movable light source. The movable mirror and light scan across the surface of the image and direct the results through a lens to the fixed mirror, which directs it to the RGB sensor. In essence, it “writes” the information as it goes. Depending on the quality of the scanner, the light source in a flatbed can be LEDs or some variety of a tube of light.

Film scanners differ slightly in how the image is captured. Strips of film or mounted slides are put into a holder that is then inserted into a slot in the scanner. In a flatbed the film is placed onto the glass platen within holders. When an image is selected for scanning in a dedicated scanner a stepper motor moves the frame across a lens that directs the image to the sensor.

Here's a Plustek dedicated 6x6cm film scanner. Frames and strips are placed into a holder that is then inserted into the film gate, which then "steps" the image across the scanning module. 

While the mechanics of a scanner are fairly straightforward, the software and capabilities of the sensor can vary considerably, depending on price and manufacturer. In the next posting I will offer some criteria that should be used to choose a particular scanner for the work you have in your collections. Scanner specs are important to understand as they will determine what you can and cannot accomplish in your work.

Every scanner works in basically the same fashion and there are a number of steps required prior to making the final scan. The first is a preview, a sort of large thumbnail (not full resolution) image, often called a “prescan.” While it serves as a rough guide to the image it should not be taken as what you could or should expect from the final scan, just as the image review on your digital camera’s LCD is certainly not what you will achieve after image processing later.

Once you have the prescan on the screen you can make various adjustments. The heart of the scanning process is the software through which you process the image. This involves choosing the resolution, the bit depth, noise reduction, dirt and scratch elimination, dynamic range, color balance and more. These choices will be examined in detail in the scanner workflow postings of this project.

Here's a screen grab of Epson's scanner software with many of the control modules opened. Image controls in software can be basic or quite sophisticated, but most allow you to make the kind of adjustments you need to create a good quality image file from the film or print you are scanning.

The changes you make to the prescan is where you set up the parameters of the scanned image, much as you set up the image-processor in a camera to deliver a certain look and resolution of a captured image. Scanning software can be quite sophisticated, and learning about its many options is key to creating quality image files from the original material.

By understanding what a scanner can deliver, and what program to utilize to get the best possible results, you will be well on the way to making the right buying decision and accomplishing your goal of archiving your precious film and print images.

Next posting: Scanner Specs

The Scanning Project-6: The Print, and Some Final Thoughts on Editing

Many folks have prints without negatives, mainly family photos from generations past, but there are also collectors and museums who have tintypes, albumen prints and even daguerreotypes. The quality of these items varies considerably, often showing signs of age due to fading, paper support deterioration and glitches in the emulsion surface. Scanning paper and other materials that support images is a fairly straightforward affair, and getting like copies is not difficult. The challenge comes in when you go to revivify, if you will, the image, a task that has been made easier with software retouching.

I am always amazed at the quality of very old prints that have been toned, and even black and whites that have been stored even under non-archival conditions. This carte de visite (about 5x7") was probably made in 1880s or so and was found in great condition. I scanned it in color to retain the sepia tone color and then did some minor retouching in software. 

 In the days when film was used for print copies, which I did commercially for many years, I would make a 4x5 negative with a copy stand setup and hand the print off, if needed and after I did my contrast and dodge and burn thing in the darkroom, to an airbrush and retouch artist, who would use the tools of their craft to reconstruct torn and damaged areas.

The success the job was heavily dependent on the original print condition and what I could do in the darkroom, and at times the results were more interpretations than true to the original image. At times the person bringing the image in for work would supply what details they had, such as eye and hair color and skin tone, and the artist would hand color the print. While the final look was at times more sketch-like than photographic, it still kept a treasured memory alive for future generations to come.

There was a time when I did a lot of hand coloring, adding photo oils to black and white prints. While the negative of this image is still in my files the only way to copy this unique treatment was scanning the print itself. The print is 8x10" so there was no problem handling it in one pass on the flatbed scanner. Image copyright George Schaub

 While the discussions here are not aimed at professional digital retouchers, I will go over some ways that an image can be enhanced and salvaged that are available to all with basic image editing programs later in these postings.

Naturally a flatbed scanner is used for scanning prints. Most of these that are not pro units offer letter size (8.5x11”) as the maximum scanning size. You can scan sections and merge larger prints later. You can also scan numerous snapshot size prints in one pass, then crop from the full scan to make corrections later. Some scanners/software can even ID individual snaps for you and create a file for each separate print; either way works fine, as you will not be sacrificing resolution whether you batch or scan individually.

There isn’t much to say about edits, as you can, with most scanners, get a virtual copy of the color and contrast of the print, and the only batch sorting you might want to do is between color and black and white and by print size. 

This is not a mistake in the way I scanned this photo I found in an old album at a flea market. The print image had gone full tilt and was very close to disappearing altogether. I scanned it first "as is."

To bring it back to life so that I could actually see the individuals in this group shot I made a simple adjustment when scanning to enhance the contrast, something I could as easily have done later in image processing software. The point is to not become discouraged when you find a poor quality print, as there are many ways to enhance and improve the image. If need be an image like this could be handed off to a pro retoucher but for me this result is mission accomplished. 

 Some Final Thoughts on Editing

Each of us has our own editing “eye” and that is certainly a personal matter. However, I could suggest that you begin the scanning process by working with projects. For example, you might want to start sorting into sections such as family, nature, florals, artwork, etc. or whatever makes sense to you. This way you can learn as you go and not feel overwhelmed by having to edit everything in your film and print files all at once. Harvest images selectively rather than trying to edit a lot of work at once.

Editing is an ongoing process (and by editing I mean dividing work into keepers, and maybes and outs) that will take time. But keep in mind that it is the most time-consuming part of this whole process, as it should be. Once you do your edits you’ll find that scanning is quite mechanical (after you learn the workflow) and easy. Scanning is an important creative process, and editing is at its heart.

How many images should you decide upon before you first begin scanning? That’s up to you and just how many images there are in your collection. I suggest that you begin with about 100, including good and not so good quality images.

You can make this your test run to become familiar with the scanner, the software and the best workflow. By working with a select group you will begin to see what you can and cannot accomplish and how you can or cannot salvage marginal images, and this will in turn feed back into your editing procedures and decisions.

To sum up:

Scanning itself is a mechanical process; although you can be creative in certain choices you make it is often best to simply scan to gain all the information you can from the material and then interpret as you will later. Scanning involves a set of decisions and commands that will affect the outcome, and each step is quite clear in its implications.

Editing is a creative process, where you make decisions about what images are meaningful to you. Editing is an emotional and aesthetic process. It becomes refined as you work through your images, and in itself is a wonderful way to revisit images you may not have looked at for many years.

There’s art in the science and science in the art of scanning, just like in photography itself.

Next posting: How a Scanner Works

The Scanning Project-5: Editing Color Negative Film

There were literally hundreds of types of color negative film, with various speeds, brands and emulsion stocks on offer. When these were mass printed in photofinishing labs, the equipment processing and printing the film identified those various stocks by their edge coding and made automatic color balance decisions accordingly. Sometimes this worked well and sometimes it didn't. 

But knowing the brand and type of color negative film you are scanning can be quite useful. You might be able to read the brand of film on the perforated strip. (See Posting 4 for a link to a site that ID’s numerous Kodak films by their codes. You can also Google a particular film or type. For example, googling Kodacolor--Kodak color negative film--will yield the years of manufacture and film codes, which can be helpful.) This information is used when applying film profiles to the scan and different profiles can be profoundly different in terms of color balance and contrast. However, knowing exactly which “vintage” (emulsion stock number) of film you are scanning is near impossible and there were variations (though they can be slight) depending on which emulsion stock number the film might have been.

This color negative film, scanned as a positive to show the orange mask, is not an easy "read" in terms of color, since both color and density are reversed and sit within an amber layer.

Here's an image of what the negative would look like when the amber layer is removed. By studying the positive (below) you can see how "reversed" colors (actually the complement to the positive colors) look. This takes some practice, although the easiest way to figure this out is to simply scan the negative, as a scanner will remove the orange mask effect in the process.

Here's the positive made from the scan. This exposure was made on Kodak VR 200, a film sold starting in 1984 and discontinued about 1986. The perf code on the film is CL, which when cross-referenced on Wikipedia led me to the film brand and type, which I used as the profile when scanning. 

While batching the types for scanning sets by film type in your initial edits is a good beginning, it is likely that you will have to fine tune the color balance yourself during scanning, which is not a difficult task, though it can be time consuming.

One problem of course is being able to see through the color mask that was incorporated in virtually all color negative film. This orange/amber coating was incorporated to enhance color reproduction, but also makes “reading” color negatives tougher than slides or black and white. Being a negative, the colors are “reversed", if you will, to their complements when the image is printed (color slide film is processed so the reversal takes place during processing via chemical or light exposure). All in all, the only way to see what colors you have (unless you have a very trained eye) is to scan the negative itself, which will eliminate the mask and make the colors positive.

When high speed films came out in the mid eighties they gave a newfound freedom to low light shooting. They did have their problems, however, as most were daylight balanced, many were quite grainy and contrasty, and I have found that the years have not been kind to their stability. This photo inside a Chicago blues club was shot in 1985 using Kodacolor VR 1000.

This is a scan from the print I got back from the lab at the time. Being daylight balanced, the film recorded an overall amber cast. I am unsure if the lab attempted to rebalance the light but I accepted it as the final output of the image at the time.  It was enough to be able to shoot in such low light without flash. 

When I scanned the negative I had to rebalance the color myself as there was no matching profile provided in the software for VR 1000. Knowing that the image was heavily influenced by artificial light I added blue and cyan and played a bit with the contrast. My aim was to produce an image that looked like it was shot with tungsten balanced film. 

However, color reversal and the orange mask are not the only issues with color negative film. In my experience, color negative films of older vintage suffer from density loss, color shifts (some are worse than others) and emulsion deterioration. There are three main color layers (CMY—cyan, magenta, yellow) within the emulsion itself, with some layers usually suffering more than others. Frankly, manufacturers did not do a good job insuring that color negatives would be “memories that live forever”, as the advertising claimed.

Of course, how you stored those negatives is also an issue, and if you stored them in shoeboxes you will probably have dirt and scratch issues to contend with as well. Not to worry, however, as color negative films can be put through dirt and scratch removal software algorithms, which will help. You can also manually clean the film by rewashing and immersing the film in PhotoFlo, or passing the film very carefully through a chamois cloth.

One option is to remove the worry about color by converting problem or poor color negatives to black and white. While this should be a last resort, it can help maintain the image if not the original color itself. Doing so you can deal with contrast and density issues and not worry about color balance.

Most software will offer a color profile of many types of commonly used color negative film. While these should be considered ballpark algorithms, they are a good place to start; in my experience you will certainly spend more time balancing color negatives film than you will when working with color slides.

So, batch the negatives as best you can according to film type and brand, check each frame with an 8X loupe and be prepared to hunt and peck to find the right color balance. We’ll cover profiling in the coming post on color negative step-by-step scanning.

My guess is that the vast majority of color negative films were shot with affordable cameras and in many cases the negatives are lost or simply tossed as being thought unnecessary. These photos are often the storehouse of precious family memories and should be scanned to protect and preserve them for future generations. I am always amazed at finding family photos in the form of black and white prints from over a hundred years ago that are still in very good shape, but mass produced color prints from only thirty to forty years ago that quite clearly are not. Scanning color prints (those with or without negatives) using a flatbed scanner is an easy matter. This print is from the 1970s and had already shifted color towards a magenta cast, alleviated somewhat by changing the color bias when scanning. 

Unfortunately, many people who shot color negative film of family and travel memories usually used other than stellar cameras and lenses. The plastic or hybrid lenses used in these cameras were notoriously soft and more than not automatic exposure modes, or guesswork, was used when shooting.

When scanning such images, expectations should be kept in check, although getting good scans for web sharing sites and even photo books—if image size is kept “reasonable”—allows these memories to be preserved. Frankly, in some cases scanning from the original snapshot print, if it’s not too far gone, may be a better strategy for such uses.

The Scanning Project-4: Editing Black & White

With color slides you can make a fairly quick assessment of quality and edit out hopeless causes (or dupes, etc.). This is not always the case with black and white. True, you do not have issues of color to deal with, and this in some ways makes it easier to separate the good from the bad and the plain ugly. You do, however, have to understand and work with density, the "thickness" or "thinness" of the negative. Those who have done darkroom work will have the advantage here in recognizing a "good" negative, but even if you don't you will quickly gain an understanding of this issue.

Here's an example of a "thin" negative. There is very little shadow detail and the contrast required to bring detail up will be excessive. If you definitely need to scan such a negative do not attempt to fix the contrast in the scan, but do so later in an image editing program. 

You also should consider quality issues such as the possible deterioration of the film base onto which the emulsion is laid (cracking, splitting, severe curvature due to roll-up storage). Other possible destructive forces can be poor processing (failure to clear hypo properly, thus staining and even loss of original converted silver) and the use of destructive storage materials or containers. 

This is a "thick" or overly dense negative that resulted from overexposure and/or overdevelopment. My suggestion is to batch these and work on them as a group as you will be using certain tools to hopefully cut through that density, although larger and unpleasing grain and contrast problems will be present.  Not all dense negatives are lost causes, but they will be challenging.

 As one of my mentors, Bob Schwalberg, used to say, “density defends density,” which means that old negatives which have been processed and exposed properly and have a rich range of tones will always do better in the long run. Well, there isn’t much you can do about that at this point, but it is self-evident that rich negatives will always yield a better scan than “thin” negatives, since the thin get thinner as time goes on. There is a another caveat: if the material was grossly overexposed and/or over-developed (thus making for a “thick” negative), many scanners may have trouble penetrating the silver (density) and harsh and possibly useless scans may result. There are ways around this (multi-scanning is one), which will be covered in the step-by-step scanning posts, but opaque negatives will always be bothersome.

Here's an example of an excellent negative that has been properly exposed and developed and shows no deterioration. This will yield a very good full tonal print and poses little challenge to get right. Shot on Tri-X 400, the scan was made using that film's "profile", a topic that will be covered in the step-by-step scanning sections in later postings. Photo copyright George Schaub.

If you have made satisfying prints from some of your negatives in the past you might think that scanning the “positive” print will deliver a better result. The problem is that darkroom printing always and necessarily compresses the full tonal values available in the negative. If the negative is truly poor or if you have only prints remaining this is the obvious way to go, but in my experience a decent negative scan will usually allow you much more creative leeway (and yield a better result) than a scanned print from that negative.

Of course, if only the print has survived and you don't have access to a negative you will be doing flatbed scanning to make a digital copy. Post scan processing can often do wonders with original prints, but in all cases you will get better results should you have access to the original negative, given that it is in good shape. This photo of "doughboys" from World War I was found in an old postcard album purchased in a flea market.

Depending on the film used or the way it was processed, you may run into grain issues. This is something you have to live with, although there are certainly ways to reduce unwanted grain when scanning and later. However, keep in mind that all grain reduction methods (called “noise” these days) entail a certain amount of image softening. Check your negatives with an 8X loupe to see if that grain will be ruinous. (It can of course be “charming” as well.) Keep in mind that scanning etches grain unlike anything you might have seen in your silver printing days, especially if you printed via a cold light head. Scanning, like a magnifying mirror, can be cruel.

Another issue to consider when editing is dirt and scratches embedded or etched into the emulsion surface. Unfortunately, many dirt reduction procedures and software programs do not work on black and white (although they do work on color film, except for Kodachromes). Retouching this stuff can be tedious, but it can be done, and in some cases you might be able to remove the objectionable material from the film itself by rewashing or using a kind of fluid as a kind of diffusion mask on the frame when scanning, a technique we’ll cover later. You might consider using a chamois cloth to clean surface dirt off the negative, and while this can help you should be very careful so as not to scratch the film in the process.

Every film type has a certain characteristic curve, and identifying the type of film you have is very helpful when making scans. Using this "profile" when scanning can eliminate a number of steps in the process, particularly with contrast selection. This is a Kodak Tech Pan negative of ice flows on the Long Island Sound. The film yielded very low grain and high sharpness. However, it tended to develop out with higher contrast than other panchromatic films, so setting its profile when scanning can eliminate guesswork later. Photo copyright George Schaub.

 Like all film, each type of black and white film has a “characteristic curve” and gamma, which means a certain contrast, density and relationship between tonal values. For example, Panatomic-X and Ilford HP5 have a distinctly different character. When editing, it is wise to batch all similar film types together. Even though there may be variations in different stocks (dates of manufacture) this allows you to set up various responses to maximize the film’s character when scanning and certainly helps in the time spent in setting up each frame. Many times a film type is not shown on the frame edge. There are web sites that track these numbers (http://www.taphilo.com/Photo/kodakfilmnumxref.shtml is one of them) although you may still have to make an educated guess in some instances. I’ll go over the importance of ID’ing film types in the step-by-step posts later.

There are other types of black and white film you may have in your collection, including black and white positive film, chromogenic film, IR film, high-speed (at the time) surveillance film, Polaroid “Instant” B&W, etc. While some of these can be challenging they can be managed, so do not disregard them in your selection process. However, they don’t usually respond in the way a “regular” panchromatic film does to scanning, and require some special setups, so batch these as well in your edits.

There are many tools you can use when scanning black and white, as well as those you can apply when processing the image in image-editing software later, so do not be discouraged if you have some marginal negatives or prints. I encourage you to work with those negatives you think are lost causes and see just how far you can take them. However, understand that they may require considerably more effort and work. Start your work with "rich" negatives and then move on to those that are more challenging.

Next posting: Color Negative Film Edits