Once changed, saved to disk, and closed, you cannot go backwards and you have to laboriously re-scan the picture again or, in the case of an image shot with a digital camera, hope that you didn't delete it after you downloaded it.

Now what's all this about scanning? Well, assuming you've shot a photograph on film, there are several ways to get it into your imaging program. If it's a slide or negative (color or B&W) you can buy a slide scanner that will digitize the image and transfer it into your imaging program. If you have prints or artwork that you ultimately want to combine in creative ways, flat bed scanners will do the same thing. Of course, if the picture's been shot on a digital camera, it goes directly from camera to computer.

Unfortunately, the art of scanning is not easily learned and can sometimes be downright frustrating...even infuriating. I'm not getting into it now because there's even a bigger problem if you scan, especially if you're a prolific photographer or have an enormous backlog of slides or negatives you want to input. A huge amount of storage space is needed, as some scanned images can result in double-digit MB file sizes.

Of course you do remember, don't you, that I recommended you buy an auxiliary removable media drive to increase your storage space. But even with a removable drive, you're going to have quite a collection of disks if you start transferring everything you want to work on at some time in the indefinite future. And finding your pictures on them won't be easy, either.

Enter Photo CD (or PCD). Here's the ideal way to transfer anything you like and not have to worry about how many removables it's going to take to store them. Not only that, but each picture is scanned at five different resolutions for you to chose from, depending on whether you want to display your photos on the web (low resolution), make up-to-5x7 prints (medium resolution) or do some stunning big blow-ups (high resolution).

And best of all, it's all done for you at your photo lab...and can cost as little as a dollar or two for each 35mm slide or negative (larger sizes cost more). You simply choose those you want transferred, and Kodak (or your lab) does the rest. You get back a shiny CD-ROM with little printed thumbnail pictures of everything that's on it.

If you don't use the Photo CD's full capacity of a hundred or so pictures, just bring that same disk back again at another time with more slides or negatives and say: "Fill 'er up!" Which is why your CD-ROM drive has to be capable of multi-session Photo CD, because little discrepancies occur between sessions and the drive has to be able to adjust to them. (By the way, I haven't come across a CD-ROM drive in the past few years that wasn't multisession, but check, just to make sure.)

Today, most imaging programs can import Photo CD formatted pictures and guess what? You CAN work from the "original" (wherever there's a rule, there's always the exception) because your real digitized original is mummified on the CD-ROM and easy to re-acquire. If you do something silly or the power goes off and you haven't saved your work, just import the picture into your program again. Of course, you'll be starting from scratch but it's better than having nothing to start from at all.

I should note at this point that Photo CDs are not the same as low-resolution floppy disks that can be ordered along with film processing and which allow you to view pictures on a monitor. Photo CD is a fully professional process that gives you multiple resolution choices based on how you intend to use your photographs and how big you want them to be.

To simplify the usually incredibly incomprehensible subject of resolution, let's begin by saying that resolution is simply a measurement of how much information or detail is contained in the image. The higher the resolution, the bigger the pictures you can print without having them "pixelate" into individual squares (pixels) that you can see. It's similar to grain in a conventional photograph.

But grain is kind of loosey-goosey and can vary from inch to inch. Pixels like to line up military-style in columns and rows: "Tennnnnn...Hut! All 640 x 480 pixels present-and-accounted-for...SIR!" That's it. Really! So rather than have you figure out all kinds of arcane (and insane) formulas, I'm going to do it for you in terms of your ultimate picture size. Your idea of good print quality may be more or less critical than mine, but I'll give you some good starting points and you can adjust upward or downward from there.

If you're going to use a picture only on the web or in a multi-media production, import it at one of the lower resolutions depending on how big you want it to display, because most monitors can only display images at low resolutions of 72 pixels-per-inch (ppi) for Mac and 96ppi for PC.

Here's a bit of basic math (don't cringe, now) to calculate just how big the screen images will be. Just divide your monitor's resolution into each of the pixel values to find out. So an image with a resolution of 384 x 256 pixels will display at 5.33" x 3.56" on a Mac screen or 4" x 2.66" on a PC's. Of course, you can always import images at high resolutions (which will display larger on the monitor) and crop smaller parts out of them.

Printed images require higher-than-monitor resolutions to look good. Since a Photo CD image consists of five files -each at a different resolution- here's how to choose the right one to import into your imaging program. The file sizes in the table are for color images; B&W (greyscale) pictures will be about 1/3rd the size.

Most of the time you'll be using Base or 4XBase resolutions for good quality print output. But if you want to experiment with many different effects (especially when you're first learning your imaging program) import your pictures at lower resolutions. The fewer pixels the computer has to march around after you give your commands, the faster they'll get into formation. While "sharpen" might take 10 seconds for a 4.5MB image, it's only a blink-of-the-eye operation at 280K.

And that's all there is to it...in the beginning. Of course there's much more to learn and you'll pick it up as you go along. I've listed some good resources below and next time, in our last Shoestring episode, we'll explore the wonderful world of output and how to make your work look as good or better than (dare I say it?) a traditional photographic print.

Good Reading

The Official Photo CD Handbook by Michael Gosney and others. (Peachpit Press, 1995, ISBN 1-56609-172-1, $39.95.) Just a bit dated, but covers everything you might want to know (and more) about Photo CD. Many examples by photographers and graphics designers on every aspect of Photo CD including authoring your own presentations, developing photographic portfolios, and editing Photo CD images. Included are two CD-ROMS packed with MAC and WIN applications, images, and clip media. It's not a "must have," but well worth having if Photo CD is going to be the prime means of storing pictures for import into your imaging program.

On the Web

This column about Photo CD is just the tip of the iceberg; you'll find the other 7/8ths at Kodak's Web Site. They began it all and have publications of their own you can order...and also some special software. But in most cases, you don't need anything other than your imaging program to import Photo CD pictures...so don't buy additional Photo CD software until you're absolutely sure you need it...which may be never.

http://www.kodak.com/daiHome/products/photoCD.shtml

If You Want a Scanner

OK, I'll admit that for some of us lazy photographers, scanners can be convenient. Sipping brandy in front of the fireplace with a snoring dog nearby, you can flip through zillions of slides, deciding which you'd like to work on that evening. Then you pop them into a scanner and, voilà, they're on the screen.

Most high-priced scanners are overkill for photographers who just want prints. They're aimed at the graphics arts trades where the image on the printed page is king...and where scans can routinely run 30MB or more. You won't require file sizes anywhere near that large so here are some suggestions that are more in line with what you need and will offer more than enough resolution for excellent prints:

1770dpi 35mm & APS scanner ($450 PC; $500 Mac):

Olympus ES-10 (A BEST BUY)

http://www.olympusamerica.com/

1950dpi 35mm scanners ($800):

(Both of these are basically the same)

Microtek ScanMaker 35t Plus

http://www.microtekusa.com/

Polaroid SprintScan 35/LE

600dpi flatbed scanners ($250):

Epson Perfection 600

http://www.epson.com/northamerica.html

Umax Astra 1200S

http://www.umax.com/graphsite/umaxen/scanners/scanner.cfm?scanners=Astra+1200S

Arthur Bleich