Scanning for Black and White

Many of us who worked prior to the turn of the century, and even somewhat around that bend, shot with film. The following is for those who still work with film and combine film exposure and development with digital scanning and printing, to me a very good course to follow, and for those who have older film images they want to print or digitize. While I now photograph mostly with a digital camera, I also have lots of “legacy” film to work with, and recommend scanning and inkjet printing as the most sensible and creative means to realize those older images.

The main thing to keep in mind when scanning is to “do no harm.” There are various schools of thought on this, but my approach has always been to get as much image information out of the film as possible without doing any, or many corrective procedures beyond that which the scanner might offer. The scanner is there to pull information out of the film record and turn that information to digital form. Scanner software can enhance that information or add to it; use it to record, not overly enhance. You should also scan at the maximum optical resolution of the scanner, and not to work with “interpolated” resolution, that is, to not add to the information through algorithms. If the scanner you use does not create the amount of information you require for your prints—in other words, produces less resolution that you need for a particular image size—then get another scanner or have the images scanned by a pro lab.

Scanners vary greatly in their specs and capabilities, and new models come out periodically, so I will not recommend or follow a particular hardware and software here. While dedicated film scanners (strip and sheet) will yield better results, a new generation of flatbed film scanner (for reflective as well as transmissive material, i.e., film) has changed the thinking on the need for a dedicated film scanner for film scanning. My choice is to work with a dedicated film scanner for 35mm and I use a flatbed for medium format.

It is a fairly simple matter to convert any color image to black and white, so you can scan color slides to color (RGB) or to black and white (grayscale) data. Most scanner software shares similar settings. You start with choosing the type of film then put in how you want the scanner to handle the film. You can scan at 16-bit grayscale, which pulls much more information than an 8-bit scan or even in color, and then convert later in software to grayscale. You then put in the “output” size, which is final print size, and also the resolution, usually 300 dpi. The software calculates the rest. Keep in mind that if you are scanning solely for black and white, choosing 48-bit color increases file size substantially.

Many scanners offer presets of various sorts, which you should test to see if they help or hinder your work. These vary from presets for film profiles, such as various types of slide and color negative films, to tone curve and color cast renditions, which can affect black and white conversions.

The mantra is “do not harm”; don’t add contrast, try to fix every exposure flaw etc in scanning. Get all the information you can from the film and then work the problems later in software. If you keep the tonal richness and detail of the original in your scan you allow the most leeway later in your image interpretation, or best chance for an faithful reproduction of the scene. It’s the same gospel as that of camera exposure. Even slides that have begun to lost dye integrity over time can be “salvaged”for black and white printing.

8 Scanning Tips

1) When scanning color negatives or slides you can scan for color or black and white. It’s easy to convert to black and white later in image editing software.

2) Scan at the highest bit depth available.

3) Test the dust and scratch removal software in your scanner to see if and when it causes unsharpness. It can help save retouching time later (except on black and white negatives and Kodachrome slides, on which it usually does not work.)

4) Scan for the highest non-interpolated resolution you think will be necessary. Do not resample in the scanner software. Never exceed the scanner’s optical resolution.

5) DO NO HARM. Do not try to enhance contrast too much or fix contrast or exposure problems; save that for the image editing software.

6) Watch for highlights. If necessary, do lower contrast in the scan phase. You are collecting information, and if you do not record the information in the scan you will not have it to work with later.

7) Think big, but be reasonable. There is a limit to how big a print you can make from various size format film. Test to see the limits of your scanner and don’t expect to solve all your problems in the scanner phase of things.

8) Scan neutral, create in software later for expressiveness.

Photos and text copyright 2010 George Schaub: Scanning can help preserve even faded or dye challenged slide film. This old Ektachrome slide was undergoing a magenta shift, but scanning it for b&w printing allowed the image to be useful again, and a nice print resulted.

High Contrast Prints: Digital and Analog

High contrast printing involves eliminating or subduing the middle tonal values, thus producing an image where the visual information is communicated in tones of pure black and white. High contrast can be used to make near line-drawing renditions, or to create highly graphic interpretations of a scene. As it mutes information in the middle values it accentuates the lines and forms that define the subject.

Virtually every image can be printed in high contrast; critical and aesthetic decisions, however, will limit this technique to certain moods or scenes. Fashion, urban landscapes, portraits, architecture and winter scenes are the most common types of images on which high-contrast techniques are applied, but this by no means limits the possibilities.

First we’ll discuss printing in the darkroom, then with computer processing. The simplest way to achieve a high contrast effect is to work with a high-contrast paper or high-contrast filter when using VC paper, namely a #5 grade. With most negatives, this choice eliminates many of the middle gray values.

Unlike more commonly used grades, such as #2 or #3, grade #5 has a rather narrow exposure latitude, which means that critical testing is key. Expose too long and the whites will "gray up"; underexposure may yield a very weak image. (#5 can also be used to correct very underexposed negatives, and will often reveal details not seen by the untrained eye.)

If even a #5 grade fails to yield the desired result, use of a "lith" film as an intermediary will do the trick. Lith (also called ortho) film is available in formats from 35mm up from specialty shops like B&H. This film is made for document and line drawing recording; when developed in a special high-contrast developer no middle gray values will record.

You can also make an inter-negative from an original negative or slide. To make it from a slide, all you need do is enlarge or contact print the slide onto the lith film, just as you would make a print. This will create a reversed, or negative image, which you can then use to make a positive print. To make a lith negative from a negative, first enlarge or contact the negative onto the lith film, and then enlarge or contact that positive onto another sheet of lith film, which will create a negative. (All photo imaging, when done on film or paper, goes negative-positive-negative-positive, and so forth. This allows for some interesting image derivations.) Lith film can be processed under red safelight conditions, so you can inspect the negative as it develops to get it just right.

Once the lith negative is created, you can retouch it with dye to eliminate any gray values that may still exist; when you opaque a negative that opaqued area will print white. After you're satisfied with the negative you can print on virtually any grade paper to obtain a high-contrast image, though a #5 will guarantee the best effect.

For those who want to work in the computer just take the image file and open up Levels or Curves and pinch in the sliders. This is like printing on a higher contrast paper. Another interesting effect is using the Threshold command (you can do this as an Adjustment or an Adjustment Layer) and use the slider to determine the look. This is pretty much a visual fix and is a very simple and fast way to do it.

High contrast does not always mean just black and white; there may be an alteration of tonal values to accentuate a "hard" contrast with some gray values remaining. This effect can be used effectively for all manner of imaging where you don't want a line-drawing effect yet want the graphic appeal of a higher-than-normal contrast image.

Photo and text copyright George Schaub 2010. This image was scanned from a high speed color slide film, then made hi-con via a Threshold New Adjustment Layer in Photoshop.

"Significant" Values

The key terms used in describing light when metering are highlight, middle values and shadow. Highlights are the brightest parts of the scene; shadows are the darkest; and the middle values lie between.

Highlights can be broken down into two main types--the principal, or textural highlight, and the specular highlight. The principal highlight is the brightest part of the scene in which detail, or texture is to be recorded, while the specular highlight is just bright tone (brightness) with no detail or texture. It may "read" on the print as paper white (the brightness and color of the paper base), something you usually want to avoid with large areas within the frame.

A principal highlight might be a freshly-painted picket fence in which you want to show the grain of the wood, or an adobe wall which has been freshly plastered. This highlight needn't be bright white; it is just the brightest value you are recording with detail or texture in the frame. A specular highlight has no texture. It can be the glint of light off an afternoon lake, or the glare from a glass-and-steel skyscraper. There is no recording of detail in this tone--it is pure light, or bright white in the print. Having some specular highlights is great--in fact, it is what often gives prints "sparkle", and you can preview them being forced into the image by holding down the ALT/Option key as you pinch the Levels slider, for example.

The other end of the brightness scale is the shadow area. The key term here is "significant shadow detail", or the darkest part of the scene in which you want to record visual information. There may be darker parts of the scene, but these will record as tone (deep gray to black) without textural information or detail.

These terms, "principal" and "significant" are interchangeable, but are very important to keep in mind when making exposures. While we do have a wide recording range on film, and must make every effort to control highlight exposure with digital, seeing the image in terms of a tonal spread, and how that spread will record, is key to making good exposures.

For example, say you are photographing a white car in bright sunlight. You take a reading off the white hood and roof and get f/16; you read the shadow cast by the car and get f/4--this presents no exposure problem, as long as you bias the exposure towards the highlight and shoot at about f/11. However, you also take a reading from the tires on the car in the shadow area, and get a reading of f/2; this is clearly out of range and you might have to resort to some fancy shadow retrieval work to get any detail back, though it is often not worth the noise and bother.

The question then becomes, is it important to record detail in the tire tread, or can the tires record as pure black (with no visual information other than tone?) If the answer is that the tires may record as pure black, the significant shadow detail is the information in the cast shadow of the car. If no, then other steps must be taken to record both the bright car and the tire tread. These steps may include adding auxiliary light (fill flash); using a reflector card to bounce light into the shadow area; or exposing so that the tires become the significant shadow area, then compensating for the overexposure of the highlights by making another exposure and then combining the two later. Or, with film, it might mean reading the shadow area in which you want detail, dropping two stops and then underdeveloping by from 10-20%.

Photo and text copyright George Schaub 2010. Seeing and reading scenes for "significant" areas of highlight and shadow is the key to good exposure. In this still life the textural quality of the objects is defined by how the brightness values are placed on the exposure scale.

Tonal Play

A photographic print has a certain rhythm--a flow of tonality, exposure and contrast that creates a cohesive image. If you open the shadows but have burnt up highlights all that flow is lost; if you have an obvious direction of light but there is a sudden intrusion from another unexplained source then the eye will reject the scenario. I’m not talking about special effects printing here, where all bets are off, where discontinuity of values can actually aid the communication, but about a more “classic” approach to the photographic print.

In addition to paying attention to this rhythm you should also consider certain tricks of the printing trade, including edge burning, center of light and breaking up fields of like-valued detail with some discrete lightening and darkening. I’ll start with the direction of light.

If you look at a number of prints closely you might notice that there is a certain direction of light within and through the image. The story goes that the film director Erich von Stroheim always lit Marlene Dietrich brighter than any other person or part of the scene. Apparently, von Stroheim would have one lighting technician follow her throughout the scene always throwing light on her face and form. This created a glow about her that became part of her screen legend.

This doesn’t mean that your main subject should have an obvious spotlight on it, but that you should pay attention to how light is handled within the scene and how it can be exploited to add subtle emphasis to your main subject. This becomes clear in portraiture, where always having the subject’s face lit brighter than the surround both focuses the eye and creates a dimensional feeling of space and volume. It also can be applied in scenics, close-ups and abstract studies. Think where the light source is coming from, about the character of that light and how you can treat the surrounding area to add just a touch of emphasis to the subject you want to enhance and draw the viewer’s eye to in the picture.

There are numerous printing tricks that can aid this process. Edge burning, for example, is a tried and true printer’s trick for bringing the eye to the “center” of the print. This is also a subtle touch, where the edges of the print are made slightly darker than the center, or main subject in the scene.

Another trick is to create visual rhythm by carefully using burn and dodge controls in areas of like tonality. This can serve to break up what might be a monotonous block of tonal values into something more attractive to the eye and make it a source of visual enjoyment rather than a placeholder in the print. For example, say you have a scene where a field of ferns that is consistently lit sits in the foreground of a deep forest scene. Rather than have a solid block of tonal values you can burn down areas, emphasize shadows and thus elevate highlights to make the area even more visually engaging. This technique can also be used on clouds, in water and even in portraits.

Photo and text copyright George Schaub 2010. The light falling on this rock face was fairly consistent. Selective burn and dodge controls varied the "density" and brought the center of light to the near upper right axis of the frame.

TONAL SCALE

Tonal scales are the blacks, whites, and shades of gray we have available in black-and-white image making. Your most important technical job when you take a picture is to record as full a range of these tones as possible. You can't create tones (especially the information they hold) on the print that don't exist on the negative or in the image recorded by the digital sensor onto your memory card.

When you make an exposure you are recording brightness values that exist in the scene. Bright areas are called highlights and darker areas shadows. The “significant highlight” is the brightest area in the scene that contains texture (as opposed to “spectral highlights”, which are glints of light like that those sparkling in a pond in the late afternoon); significant shadow values are the darker areas in which detail or image information appears, as opposed to deep shadows, which are just deep tones without detail, like the shadows cast on a bright day.

Of course, your recording contains more than just bright and dark areas-there's a whole range, or scale, of tonal values in between. These go from near-black to near-white, with all the myriad shades of gray. Some photographers differentiate these shadings into eleven Zones, numbered 0 through 10 (with 0 being pure black and ten being pure white.) There are of course many more steps or better stated a full gradient possible. Most importantly, regardless of how you slice it, the tonal scale recorded during an exposure defines the range of possibilities within the print. Have a broad scale of tones, or in film, densities, and there's a good chance you can generate same on the print. There are simply more options, both creative and corrective, when you record as many of the brightness levels within the scene as you can, and as the medium allows.

Photo copyright George Schaub, 2010. This print shows a full range or scale of values from deep shadows to textured highlights.