Análisis de trabajos previos

When we contemplate data storage for computers, we normally think in the short term. Our fi rst concern is the immediate one: how much hard drive space to have. Then we think about how we back up our system in case the operating system crashes or a hard drive fails.

The more prudent among us think about off-site backups, ensuring that a copy of the data on our hard drives is stored someplace other than the home or offi ce where our computer is. That way a major disaster at the computer’s location loses only hardware, which is easily replaceable. Still, this is thinking about the short term; backups go out of date pretty fast.

Restoring photographs engages us in a whole new concept of time. Months and years are minor matters; it’s decades and possibly even centuries that concern us. The photographs we restore may be as young as 15 or as old as 150 years, but we’re restoring them because they’re important to us and didn’t last in their original form. One of the great promises of digital restoration is that in principle the restored photographs can last indefi nitely.

The last chapter of this book, Chapter 13, “ Archiving and Permanence, ” covers this subject in detail. As I argue there, currently the two best ways to store your fi les are DVDs and hard drives. In terms of convenience, durability, and cost per bit, both forms of media are excellent.

One advantage of storing your fi les on DVDs is that this approach doesn’t require much additional money; your machine may already have a DVD burner. High-quality DVD blanks are inexpensive. The (relatively!) small capacity and low unit price of DVDs (or CDs) can be handy, especially if you want to distribute work to several people.

Removable hard drive storage requires a bit more of an investment, but the cost per bit becomes very competitive when your storage requirements mount up into the hundreds of gigabytes. Hard drives have gotten incredibly cheap; they cost about one-third as much per gigabyte as archival DVD blanks. You have to buy your storage in chunks that cost tens of dollars instead of tens of pennies, but it’s hard to beat the convenience and compactness of a hard drive.

For a few 10-spots, you can buy a removable hard drive bay or drawer for your computer that lets you use standard hard drives as removable media ( Figure 2-6 ). A hard drive bay is a hollow shell into which you plug trays or caddies that contain ordinary internal hard drives. The bay is attached to the data bus of your computer; it has internal connectors that mate with the tray to connect the hard drive to the computer. You install a drive in a caddy, plug the caddy into the bay, and read and write data to it just as though it is a regular hard drive inside your computer. There’s no muss or fuss, and you don’t need special software, as you do when burning DVDs. Because of the interface circuitry, these bays are sometimes not quite as fast as hard drives installed directly on your machine, but they will still be much, much faster than reading and writing data to DVDs.

With hard drive caddies, a year’s worth of work can fi t on a single drive and go into your safe deposit box for safekeeping and security. With a hard drive bay, you’ll also likely never run out of internal hard disk storage. You can reserve your internal hard drives for the critical stuff such as your applications, scratch fi les, and those fi les and documents you really need to have on your machine all the time. Everything else can go on removables.

Look for a hot-swappable caddy. Hot-swappable caddies are more expensive, but they let you treat the hard drive tray like any other removable storage medium. You can insert and remove hard drive cartridges without having to

Fig. 2-6 Ordinary IDE or SATA hard drives, installed in removable hard drive trays, are great for external and offsite fi le storage. They are as cheap per gigabyte as CDs and DVDs, and they’re much faster than those storage media.

power down and reboot. If you’re maintaining duplicate backups, as you should when archiving, that’s a big convenience factor. (If you try to exchange drives in a non-hot-swappable caddy while the computer is on, the least that will happen is that your operating system will be very confused and unable to recognize the new cartridge until you reboot. The worst is that you can destroy data on your drives.)

Drive bays are also available as external devices, usually for more money. They’re good if you don’t have a spare slot in your computer case or if you want to move the bay between different computers. Two sources (among many) for bays are OWC (Other World Computing) and Weibetech. Both are very well regarded.

Scanners

Flatbed scanners that cost no more than several hundred dollars will do quite well for print restoration work. They are limited in their ability to capture very high densities and extremely fi ne detail. Fortunately, you’ll fi nd that 99% of the time the print to be restored isn’t very contrasty; sometimes it’s so faded as to be almost invisible ( Figure 2-7 ). Being able to capture high densities with the scanner just isn’t very important. Similarly, resolution won’t be a major worry; you’ll hardly ever fi nd an old photo that you need to scan at more than 1200 ppi.

On the other hand, being able to capture at 16-bit depth is critical. You won’t always need to scan your originals at 16 bits per channel, but some originals will be so badly faded or distorted in tone and color that you’ll need to capture the most subtle differences if you want to get a good-looking restoration. These days my habit is to scan everything at 16-bit depth and decide later whether I need to keep all those bits or down-convert to 8-bit color. Mostly, I hang onto all the data.

Based on these considerations, just about any midrange fl atbed scanner you can buy today will do for restoring prints. One feature to consider, if your budget permits, is a fi lm adapter for the fl atbed scanner. Usually these take the form of a special lid that includes a light source so that the original can be illuminated from the back instead of from the front, as you would with a refl ection print ( Figure 2-8 ). In some scanners there’s a separate tray for loading fi lm into the scanner.

The advantage of a fl atbed scanner is that it does not cost a great deal of money to get the capability of scanning 5 7-inch and 8 10-inch fi lms and glass plates. Dedicated fi lm scanners for anything larger than the 120-roll fi lm format are extremely expensive. Old fi lm that is not the same size as modern standard formats (and much of it isn’t) is sometimes physically diffi cult to

Fig. 2-7 Old photographs (top) often look hopelessly faded to the naked eye. A good scanner, used properly (see Chapter 4), can recover an amazing amount of detail that’s nearly invisible to us (bottom).

scan with a dedicated fi lm scanner, which may have fi lm carriers that can only accommodate specifi c formats.

Be aware that older fi lms and glass plates, unlike prints, frequently have extremely high density ranges, even when they are damaged and faded. They can also have lots of fi ne detail that will require scanning at high resolutions to capture. If you’re going to be regularly scanning old B & W sheet fi lm or glass plates, you’ll have to spend $ 500 on a high-quality fl atbed scanner. For occasional use, a lot less’ll do you.

A fi lm adapter for a fl atbed scanner is not a substitute for a dedicated fi lm scanner for smaller formats; such a scanner will almost always capture the fi lm with much better resolution, more accuracy, and a longer density range. If you plan to work from roll fi lm or 35 mm originals, seriously consider buying a high- quality fi lm scanner. The quality you will get from a fi lm scanner will almost always run rings around fl atbed scans.

Make sure you get a fi lm scanner that includes Digital ICE 3 _{. That scanner} software has three tools: Digital ICE, Digital GEM, and Digital ROC. Digital ICE removes scratches and dirt from color scans amazingly well ( Figure 2-9 ). It does not work with silver-based B & W fi lms (although it will work fi ne with chromogenic ones like Ilford XP2), and usually it won’t work on Kodachrome slides. In all the other cases, it does a vastly better job of eliminating dirt and scratches than any post-scanning software can.

Some fl atbed scanners include a software-only version of Digital ICE, and it doesn’t work very well. Hardware-based Digital ICE performs an infrared scan of the sale. Color fi lm dyes (except Kodachrome’s) don’t absorb much infrared; dust and scratches do. That gives the software the information needed to subtract dust and scratches from the scan, and it’s why Digital ICE won’t work with Kodachrome (usually) or with B&W fi lms.

Fig. 2-8 Get a scanner with a fi lm-scanning lid like this one. Then you’ll be able scan prints, sheet fi lm, and glass plates for restoration. A dedicated fi lm scanner, though, will serve you better for scanning roll and 35 mm fi lms.

Some fl atbed scanners have real infrared Digital ICE; most don’t. How do you fi nd out what a fl atbed scanner really has? Download the full manual for the scanner from the manufacturer’s Website. If the instructions for Digital ICE warn that the software won’t work with B&W or Kodachrome fi lm, you’ve got the real deal. Otherwise, I’d be skeptical.

Digital ROC (which restores color) and GEM (which reduces noise and grain) have plug-in counterparts (reviewed online) , so it’s not absolutely necessary to have them built into your scanner. I still think it’s a good idea. The scanner versions work differently from the plug-ins, and the capabilities of the two versions complement each other. In addition, the scanner versions have access to the raw scanner data, which can sometimes make a big difference in the quality of the results.

For example, the scanner’s Digital ROC does a really good job with contrasty originals because it works on the raw scanner data before the regular scanner software “ corrects ” brightness and contrast. In Chapter 11, “ Examples, ” the only way I could capture the entire range of the slide in Example 4 in a single scan was by using Digital ROC ( Figure 2-10 ), and it did the job beautifully.

Printers

At the turn of the century, I would’ve gone on at some length about just what kind of printer you ought to buy. I’d have discussed the pros and cons of inkjet versus dye sublimation printers and the differing characteristics of the Fig. 2-9 Digital ICE,

built into many fi lm scanners as part of the Digital ICE 3 _package,

is the fi rst line of defense against dust and scratches. This Kodachrome slide was scanned without (left) and with (right) Digital ICE. Digital ICE usually doesn’t work well on Kodachrome slides, but it worked OK with this one.

pigment-based and dye-based ink sets. I’d have spent a lot of time talking about comparative print longevity, tonality, color gamut, and overall print quality.

My considered opinion is that this is all now water under the bridge. Spend several hundred dollars and you will get a printer capable of making excellent and long-lived prints. It doesn’t matter whether you’re buying a current, top-tier Epson, Canon, HP, Kodak, or Olympus printer. Prints right out of the box are going to look very good; prints made with a custom profi le (see Chapter 12, “ Printing Tips ” ) are going to look excellent.

Meaningfully distinguishing between printers requires full-length reviews of each one, just the sort of articles I write for the photography magazines that run several thousand words. I don’t think you bought this book to read 20,000 words ’ worth of printer reviews.

Fig. 2-10 Digital ROC is available as part of the Digital ICE 3 _{scanner software and as}

a Photoshop plug-in. (a) This Ektachrome E-1 slide from the early 1950s is badly faded and too dark. (b) Here is the same slide scanned with Digital ROC turned on. Great color and good tonality, automatically! (c) The green channel (magenta dye image) from (a). Without Digital ROC the scanner was unable to pull out any shadow detail. (d) The green channel recovered by Digital ROC, from (b).

It used to be true that one could make important statements about print longevity and color gamuts that were true across all printers of a particular class. That’s not the case any longer. If one has faith in the accelerated tests, on average pigment-based inkjet prints will have a longer life than dye-based inkjet prints, but some brands of dye-based prints have longer lives than some of the pigment-based prints.

Besides , any of these printers produces prints that will last on display for many decades and in albums and storage for considerably longer. Overall, these new digital prints are likely to prove much more stable than the original photographs on which they were based.

Personally , I take published longevity numbers with a big grain of salt; there’s still a lot we don’t know about these new media. But that doesn’t give me any reason to favor one class of print over the other. Uncertainty applies across the board, and all we can do is take the numbers at face value and keep our fi ngers crossed.

The prints won’t all look alike. I defi nitely have my personal preferences, and so does every other fi ne printer I know, but those preferences are

completely personal and subjective. I can tell you that I use an Epson 2400 printer and like it a lot, but that’s no assurance that you would like it is much as I do.

Continuing in this vein, I see less and less difference every year in the kinds of print densities and color gamuts produced by pigment- and dyed-based inks. Again, on average, dye-based ink prints will have higher maximum densities and larger color gamuts than pigment-based prints. But just as with longevity, this is merely an average for which there are notable exceptions; some of the kinds of pigment-based prints are defi nitely superior in all respects to some of the dye-based prints. Even the average quality difference is becoming less signifi cant; pigment inks have been getting better faster than dye inks.

Another nonissue is printer resolution. By that I mean the dpi that’s given in the printer manufacturer’s specs. That droplet-per-inch value is now so high that it’s been years since I tested any printer where the individual droplets were visible at a normal viewing distance. A greater number of ink drops is only loosely connected to the actual resolution of the printer. (See the sidebar for an explanation of how dpi and ppi have gotten confused.)

I realize this doesn’t give you very much specifi c information to go on when selecting a printer. Sometimes, though, it can be very valuable knowing what not to pay attention to.

That ’s it for hardware shopping. Next you’ll need some software to make that hardware useful, so it’s on to Chapter 3, “ Software for Restoration. ”

PPI, DPI, Resolution: What’s the Diff?

“ Dpi ” has become a much misused and overused term. Image processing programs adopted this traditional printing term to make things less confusing for the graphic arts business. It has not quite worked out that way! Originally dpi meant halftone dots per inch when talking press reproduction with screened plates, such as those used for magazines and newspapers.

Today , dpi is also used to mean ink droplets per inch (for inkjet printers) or pixels per inch (for image fi les and full-color devices like displays, photographic output devices, and dye sublimation printers). In other words, dpi doesn’t refer to a single standard unit of measure. This is a seriously confusing situation for lots of people.

To begin with, image fi les don’t come in dots, they come in pixels. Pixels and halftone dots aren’t the same thing; most software requires somewhat more than one pixel to generate one sharp halftone dot. The correct measure of digital image resolution is pixels per inch, no matter what your software says. That’s why I use “ ppi ” instead of “ dpi ” when I’m actually talking about image pixels, and it’s a habit you might want to try to get yourself into.

Your inkjet printer is not rated in ppi. In fact, it isn’t even rated in dots per inch. An inkjet printer’s dpi really means “ ink droplets per inch. ” A droplet isn’t a pixel or a halftone dot; it’s just a blob of ink. The key difference is that a single pixel or halftone dot can convey the range of tones from black to white. Inkjet printers can make droplets in at most a few different sizes. The printer uses a fi ne spray of droplets of each color to build up continuous tone, with more droplets to produce higher densities ( Figure 2-11 ). It takes several ink droplets of each color to make up a full- color, full-tone pixel. So the actual resolution of the printer when you’re printing out continuous- tone color is considerably less than the printer’s offi cial dpi. That’s why you need a printer with a much higher dpi than your fi le’s ppi in order to get good tonal reproduction.