RELACIÓN LABORAL

If you’re working from roll fi lm originals, a high-quality fi lm scanner is in order; if you’re trying to scan old B & W sheet fi lm or glass plates, a very good fl atbed scanner is going to be necessary. Old glass plates and sheet fi lm are especially challenging to scan well. Old-style photographic emulsions were typically much more contrasty than modern fi lms. The older the photograph, the more likely it is to place severe demands on your scanner’s ability to capture detail in the highlights, the densest parts of the negative ( Figure 4-26 ). In the Examples

Fig. 4-24 These are the scanner software Levels settings I used to create Figure 4-23 . I set the black and white endpoints inside the range of tones seen by the scanner. That makes the ink blacker and the paper whiter, minimizing or eliminating stains and faded spots in the halftone and making it much easier to restore this photograph.

online at http://photo-repair.com/dr1.htm , I do a complete repair and restoration on this photograph.

The situation is made worse because the grains of silver that make up the image are more likely to scatter light out of the optical path than back into it. Consequently, most scanners read B & W silver emulsion densities as being much higher than what you would measure on a densitometer and higher than the equivalent density in a dye-based (color or B & W chromogenic) photographic image. For example, my Minolta DiMAGE MultiPro fi lm scanner can handle about 4.2 density units (du) in color fi lm and chromogenic B & W fi lm like Ilford XP2, but it’s limited to silver-based B & W densities of 2.7 to 3.0 du.

Fig. 4-25 This is the histogram for the halftone scan in Figure 4-23 .

Fig. 4-26 Old B & W fi lms and glass plates are often very dense and contrasty. They demand a lot from your scanner. I was just barely able to capture a good scan of this cracked glass plate negative on my professional fl atbed scanner.

That ’s a lot by modern darkroom standards, but unfortunately it’s not by early photographic standards; the printing materials they used then had extremely long exposure ranges. Adding to the diffi culties are early photographers ’ predilections for generous exposures. Emulsion making and exposure determination were nowhere near the precise crafts that they are today. It was far better to have to “ print through ” some extra and unneeded density than to underexpose and be saddled with an unprintably thin or mostly blank negative, so the majority of old fi lms and plates are dense.

The only times when you’re not likely to see high B & W densities are when the original is severely faded or bleached, as in Figure 4-20 . That doesn’t

make repairs any easier! Such damage is rarely uniform across the photograph, and a very narrow contrast range in the negative only serves to exaggerate the impact of dirt and scratches.

Whenever you scan contrasty and high-density originals, regardless of the fi lm format or type, be sure to mask off the unexposed areas at the edges of the fi lm, fi lm sprocket holes, and the clear parts of the fi lm carrier or platen. The unattenuated white light blasting through those clear areas will cause fl are that degrades the quality of the scan if you don’t block it ( Figures 4-27 and 4-28 ). Good fi lm scanners come with masks for different formats, so you

Fig. 4-27 Clear areas around the image must be masked off when scanning a dense negative. The upper fi gure shows the scan I made of this glass plate on my fl atbed scanner when I didn’t mask off the clear areas of the platen. The lower fi gure shows the scan made with exactly the same settings, but this time I used black paper to mask off the region outside the image. Figure 4-26 shows what a difference this made in the quality of the highlights (densest parts) of the negative.

shouldn’t have to worry about this. When scanning dense fi lm or plates on my fl atbed scanner, I just mask off the surrounding area with strips of black construction paper. It’s simple, even primitive, but it’s most effective.

Scanning old B & W plates and fi lms is best done in 16-bit mode using whatever scanner settings will let you capture the maximum density range. Finding out what those settings are for your scanner will take some experimentation. In some scanners, 16-bit mode automatically captures a longer density range; in others (my Minolta DiMAGE, for example) there may be a separate mode with a name like “ 16-bit linear ” that captures the longest density range.

Even though you are scanning a B & W negative, you may fi nd that you can capture the longest density range if you tell the scanner software that you’re working with a color transparency. Frequently scanner software tries to be “ helpful ” and scan for normal-contrast results. The software boosts contrast and restricts the range of densities you capture if you scan the fi lm as a negative instead of as a transparency, because modern negatives, B & W and color, have lower density ranges and less contrast than slide fi lms.

Fig. 4-28 Here’s an enlarged portion of the unmasked (left) and masked (right) scans. I lightened the scans and increased their contrast to make more visible the highlight detail (the dense parts of the negative). Even though this area is in the very center of the plate, far from the unmasked edges, fl are has crept in and lightened the high-density areas. It also reduced contrast; the folds and ripples in the white dress aren’t as clear in the unmasked scan as the masked one. The masked scan has much better highlight detail and contrast.

How to inspect very dark parts of a scan

You can use the Curves tool to exaggerate the highlight detail, making it easier to compare quality between the scans. Open the scan fi les in your image processing program, bring up the Curves tool, and create a Curve like the one in Figure 4-30 . If you’re using Photoshop, do this in a Curves adjustment layer. That’s a better way because you won’t be altering the photograph itself, just its presentation. Then if you forget what you’re doing and accidentally save the fi le, you haven’t destroyed any information. A Curves adjustment layer also lets you move the control points in the curve around to make it easier to see different aspects of the highlight density.

You will need to run some experiments to fi nd out what combination of these settings works best with your equipment. Don’t worry about what gets captured in the shadows (the thin parts of the negative); they will take care of themselves. Concern yourself with how much information you capture in the densest highlight areas ( Figure 4-29 ). Find the scanning mode that gets you the maximum amount of highlight information, and stick with it for all your scans unless the original is severely faded.

Fig. 4-29 An easy way to check whether you’ve got good highlight detail in the scan of a very dense neg is to increase its brightness and contrast using the curve in Figure 4-30 . The photo on the left shows the scan viewed normally. The photograph on the right shows the same scan after I applied the enhancing curve in Photoshop.

When you are working with extremely contrasty originals, consider making two scans with very different exposures — one for the highlights and one for the shadows. In Photoshop, you can use the Merge to HDR automation to combine several differently exposed 16- or 8-bit fi les into a single, extended-range image. Picture Window has a simple tutorial explaining how to do this using its Stack Image operation. This operation is a lot more intuitive than Photoshop’s automation, and I like Picture Window’s results much better. I give you detailed instructions on using it in Chapter 9, on page 298 .

Depending on the capabilities of your scanner, combining multiple scans may not capture a longer density range than a single scan could. But it will get you much higher-quality data in the extreme highlights and shadows, with less noise and better tonal separation.

Be aware that, just like point-source enlargers, most fi lm scanners also really exaggerate scratches and dust and dirt. There are software tools that will help reduce that, but using them without compromising sharpness is

tricky. Hardware-based scratch and dust suppression, such as the DIGITAL ICE found in dedicated fi lm scanners, won’t work with silver-based images. Resign yourself to the fact that a certain amount of “ spotting ” is necessary with any scan. This is a situation where the Polaroid Dust & Scratches Removal program (see Chapter 3, “ Software for Restoration ” ) could help you out considerably.