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.

Hand Work on Negative Printing

This entry is for chemical darkroom printers, but those who print strictly digital might find it of interest as well, as it covers some of the same techniques, and even terminology, used for inkjet work. It takes up the discussion after the test print stage where overall exposure time has been determined.

After you have determined the proper overall exposure time for the negative, you may discover that certain tonal areas are not reproducing to your satisfaction on the print. For example, some highlights may be too harsh and lack detail, or some shadow areas are blocked up and lack separation. Before you go on to any mechanical steps to correct this problem, recheck your testing procedures. First off, take another look at your negative. Are there tones available that you just don't see in the print? Have you squelched your values to the point where the sacrifice is too great? Is your paper contrast grade too high or low? If it's too high, you may be causing a blockage in highlights and/or shadows. If it's too low, your highlights may be fine but your blacks are weak or, conversely, your blacks are fine but your highlights lack sparkle. Is overall exposure time correct?

Recheck your test strips and ascertain whether another time may yield a better tonal scale. If all these backup checks don't reveal the source of the problem you may simply have a situation where the negative itself doesn't have the information you need, or the contrast of the negative is such that a normal printing paper simply can't handle the range of tones. This is when dodging or burning in may come to the rescue.

DODGING
When you hold back the light from a select portion of the negative as it's being projected onto the paper you are dodging. Generally you'll need to dodge during printing when you fail to compensate properly for scene contrast in film exposure. A typical situation that forces dodging is when your principal subject is highly backlit, or when a portion of a subject is obscured in a bothersome shadow, such as under the brim of a hat. In each case, the area to be dodged has not received enough exposure, and is quite underexposed in relation to the rest of the image. You also may have to dodge a portion of a landscape scene when, for example, the sky is quite bright and the land becomes underexposed because you failed to compensate, through exposure or filtration, to bring the brightness values into a printable balance on the film. Whatever the reason, dodging is always used to help bring detail into underexposed shadow areas, as it keeps the darker tonal areas from being overexposed, or printed too dark on the print. This is accomplished by holding back some of the printing light during the overall exposure.

Dodging should never be overdone, as too much will destroy the tonal integrity, or flow, of the overall image. Shadow areas are truly darker than the rest of the image, but they shouldn't be weaker in tonal rendition. An over-dodged area will stick out like a sore thumb, and will look "muddy" and weak. Better to dodge with a light touch; better yet to work it out in negative exposure.

The best dodging tool is a small piece of cardboard taped to the end of a flexible, but sturdy wire; a thin coat hangar wire works admirably. Before you do your final print, practice a bit with the focusing light on. Place the end of the dodging tool between the light source and projected image and cover the area to be dodged. Now feather, or move the blocker back and forth quickly over the area. Don't just place the blocker over the area and hold it there-you'll create a tonal edge that's simply too forced and obvious. Work it like a swivel stick and keep stirring.

There's no hard and fast rule about dodging, but it's usually best to limit dodging to less than one-quarter of the total exposure time; any more and the effect may be too obvious. Thus, if total exposure time is twenty seconds, dodge for no more than 5 seconds. If you still can't get detail in the area you may be working with a lost cause and/or may be working on the wrong contrast paper for that particular negative. Experiment with a number of prints to get the right proportion of dodging to overall printing times. If you blend your light well you may be able to get away with a higher proportion of printing to dodging time.

BURNING-IN
When you add exposure to select portions of the print over and above the tested printing time you are burning-in. Generally, you burn in to add detail or texture to highlight areas, although you may also burn in dark areas to get blacker-blacks or to obscure shadows areas for a more dramatic presentation. There's also a technique known as edge-burning, which adds a subtle touch of exposure to the sides of a print.

First off, follow the same double-checks discussed in dodging to make sure that the cause of your problem isn't improper paper contrast selection or too little printing time. If the contrast is too high you may have good separation in your shadow areas but harsh highlights; if the printing time is too little your blacks will be weak and there will be no details even in mid-highlight areas.

In general, you'll be burning in to counter the harshness of contrasty scenes, where the brightest tonal areas (those areas on the negative with the greatest density) print with little or no detail. Subjects may include artificial light sources in low light scenes, reflections from metallic objects, and any area that receives too much exposure on the negative vis a vis the rest of the image, thus causes an imbalance of densities.

When you add exposure time over and above the normal exposure you are adding print density to select areas. This is accomplished by allowing light to hit certain areas of the print while holding it back from the rest of the projection. You can do this with your hands, with holes cut out in opaque cardboard, with the edge of a board, or by using templates, or forms cut out to match the areas that are to be blocked. Let's look at these one at a time.

If you've ever used your hands to make shadow plays on a wall you have an idea of what a versatile tool your hands can be for burning-in. Nearly any shape can be created by manipulating your fingers and palm, from straight lines to curving arcs. In addition, you can use both hands to create a funnel of light and can vary the amount of light going through by simulating the aperture on a lens by moving your hands in and out. Hand burning-in takes some practice, but as you gain experience you'll find it's very flexible.

The most common way printmakers burn in is with a hole cut in a piece of opaque paper or cardboard. Once the area to be burned in is identified, you cut a hole out in the paper or card that corresponds to the area (the larger the area, the greater the diameter of the hole), place the paper between the light source and the paper and feather the light onto the area. As you'll see, the farther away you hold the card from the paper surface the greater the area of the projected circle of light; it works just like a cone. Two tips: 1)Make sure that the burning in tool is quite a bit larger than the printing paper on which you're working; this ensures that you'll have no unwanted light leaking over the edges of the burn card onto the edges of the printing paper. 2) Burn by blending the light onto the area rather than just holding the burn card in one spot. As with dodging, creating a "no seam" look, where tones flow from one area of density to another, is critical.

One advantage of working with an opaque card is that you don't have to watch the light hitting the paper on the easel itself. By holding the burning tool above the easel you can see exactly where the light is playing on the surface by looking at the card itself. Naturally, having a white card helps. This close-hand viewing is an invaluable technique, as it makes what can be a clumsy experience into a smooth operation.

You can also use a card to burn in edges, corners, or a large horizontal or vertical area of the print (such as horizon lines). In this case you use the same blending, or feathering technique to get a flow of tones. Again, watch the areas not getting additional exposure on the surface of the card.

The last technique for mechanical burning-in is used when a highly amorphous shape, or unique form, must get additional exposure. (This can also be used for dodging.) Here you'll be cutting an opaque template of the area by laying a cardboard or thick paper on the projected print and sketching out the form. You then cut out the form and place it over the printing paper during exposure. If you use this technique, keep in mind that you may have to do additional blending with the small cutout burn card to keep the tonal borders from looking false. This is a tricky technique that requires practice to get right.

You can also burn and dodge and get varying grades of contrast on the same print by using a split-filter printing technique with variable-contrast papers. This opens up even more possibilities for solving underexposure (dodging) or overexposure (burning-in) problems, and is a way of solving some problems that can't be handled with a graded contrast paper.

Let's say that you have a difficult negative, one that has a contrasty background sky (one that neds a lower contrast to bring out detail) and a slightly underexposed foreground that would normally call for a 3# grade. This is a fairly common negative.

One way of dealing with this situation would be to boost the overall contrast with a #3 filter, then burn in the sky. This may work well, but too much burning in may result in a flat look to the print, even though the exposure is correct. With variable contrast papers you can make the first exposure for the foreground with the #3 filter, then, being careful not to bump the enlarger or changing the focus, replace it with a #1 filter. You then make a second exposure to activate the low contrast layer in the variable contrast paper, dodging the foreground with your hand or an opaque sheet of paper as you do. This takes full advantage of both contrast layers in the paper.

How much burning in should you do? As much as necessary to get the tones right. If you're shooting in a very contrasty lighting situation and can't or don't balance exposure accordingly, you may have to burn in as much as two or three times the overall exposure; even then you may have to go more. But if you find that you always have to burn in anytime you shoot on a bright day you probably are creating your own problems-check your exposure and/or film development procedures.

Copyright text and photo: George Schaub 2010
This original was exposed on Tri-X at -2 stops from the significant shadow reading and underdeveloped 10% in D-76 1:1 at 9 minutes to try to hold back density on the highlights. The shadow details were fine but the highlights were quite "hot." The contrast was resolved by burning in the foreground and top of the image. BTW, each lightbulb in the shadow areas was burned in using a small cutout in cardboard.

Grayscale Step Wedge

One advantage digital printing has over the conventional darkroom is that you can see on the monitor how your tonal scale—the range of black to white and all the shades of gray between-- will be reproduced. The main problem for most printmakers is that they tend to make prints with too much contrast, thinking that this will enliven their images. Too much contrast means loss of highlight detail and a harsh looking print. The advantage we have with digital printing is that we can measure and even predict when no ink will land in a spot and when we’ll get paper rather than ink occupying space within the frame of the image.

With conventional paper printing you can fog the highlights slightly to add tone. In digital printing you create highlight density through ink. A thin shot of ink, to be sure, but you still do it with ink. If you can train yourself to watch for the highlights and to be able to measure for them and preset your printer to always catch them you’ll go a long way to solving one of the main problems of digital printing.

The same goes with shadow detail. You may see the shadow detail on your monitor but when you make a print they go to tone and lose detail. Or all the lower values bunch up and overlap. This type of print output is unacceptable, especially when it is so easy to overcome. Of course, if the digital image files does not have these tones (or gray levels, if you will) then we cannot get them on the print. Burnt up highlight pixels will just go gray and lost shadow detail will just reproduce as dark tones. But if the detail’s in the scan or digital file it should be able to be reproduced on the print.

One way to work with tonal values is to create a grayscale step wedge, check it on the monitor and print it out. Open a New file in Photoshop and make it about 5x7 inches at 150 dpi. Make the file in grayscale or RGB mode.

Once you have done that create a selection within the blank new document using the rectangular marquee. Do not feather the edges at all.

Next click on the gradient tool and set the default of black/white in the foreground color box opener, if necessary. Now hold onto the shift key and draw a line from one end of the New file window to the other, making sure it is a straight line and that it stops at the edges of the box. You should see a smooth grayscale gradient from black to white.

Now go to Image>Adjust>Posterize and choose 11. Now look at the scale on the screen and see if you get separation between the tones and that your white has texture.

Check if and where you begin to lose information in the step wedge. How many steps back does the white and black areas begin to differentiate (in other words where does the tonal separation start to take place)?

If you have a very harsh, contrasty image there is something not right with your monitor settings. If the grayscale is bunched up there is too high a contrast setting.

Save the step wedge you’ve made and call it up once in a while. I know some printers who keep it as a constant companion on their screen, although I find that there’s enough screen info to deal with without the step wedge sitting there.

Copyright George Schaub 2010