Chapter7.Sharing your Photos with the World

Chapter 7. Sharing your Photos with the World

What good is it to have a beautiful photo like this if you can't share it with anyone? (Photo by Reed Hoffmann)

After the hard work of preparing for your photo trip, the fun of photographing new things, and the exhilaration of experiencing new places, it's time to show off your pictures. If you've gotten this far, you already have the tools you need to share your photographs. From physically giving people your photos to posting slide shows online, sharing your photos couldn't be easier. And it's one of the most satisfying parts of digital photography.

Digital photographs are strange because they don't really exist. Every digital photo ever taken is simply a recording of zeros and ones arranged in the same language that all computers speak. Although a digital photo isn't real, it starts off the same way as a film photographlight passing through a lens, striking a surface. But the digital image is recorded as a stream of numbers representing the strength of the light and its color at each of the photosensitive pixels across the face of the imaging sensor.

In order to reproduce a film photograph, light is passed through the original negative and projected onto a sheet of light-sensitive photographic paper. The process results in a slight loss of quality due in part to the nature of light, but also to the limitations of the technology.

Digital photography doesn't have as many limitations, so each copy of a digital photograph will be identical to the one before it, with no loss in quality. This makes sharing digital photographs much easier.

There are any number of ways to show off your travel photography that don't involve huddling over the back of a camera peering at tiny images. And unlike the old days of sitting in a darkened room being bored to death by a relative's slide showfeaturing real slidesmodern photo sharing is fun and easy.

Figure 7.1. Because it's made up of pixels, a digital image file can be copied endlessly without degradation. To share it properly, though, learn the difference between what's needed for a good print and a photo attachment you send via email. (Photo by Reed Hoffmann)

Digital photos can be shared physically or virtually. One approach requires a physical print, and the other way requires that you send your files in a format, usually on a CD or as an email attachment that can be viewed without having to make a reproduction. Both have their advantages. Which method you choose has a lot to do with the amount of control you like to have over your work, and how much time you want to spend.

Pixel Pusher

The number on your camera that indicates the sensor size in megapixels doesn't just indicate the resolution of the photos it takes, it also gives you an idea of what you can do with the photos that come from that camera.

Across the face of the imaging sensor in your camera are light-sensitive spots called pixels. Each one of them records how much light strikes it, and combined they make up an image. A camera sensor with 1000 pixels across and 1000 down is a one-million sensor. Cameras with such a sensor are known as one-megapixel cameras.

In order to display that image on a computer screen, each dot needs to be represented on your monitor. Inside a CRT monitor is a little light-emitting "gun" that paints the picture pixel by pixel on a surface that glows when struck by light. (An LCD monitor employs different technology, but the idea of painting the image a pixel at a time is the same.)

The average monitor can paint about 100 pixels in every inch of screen space. Divide the 1000-pixel resolution of the camera by 100 and you'll get an image that's approximately ten inches wide when displayed on a screen.

The average inkjet printer has big bold letters on its box saying that it can print at 1440, 2880, or 5760 dpi, depending on the model. In order to figure out how big your image would look on a monitor, we divided the resolution of the camera by the resolution of the monitor. That works for your computer display, but printers are a bit more complicated than that.

All computer printers have both an input and output resolution. The output resolution is that number printed on the box1440, 2880, 5760, and it's how many dots of ink are laid out in an inch of space. If you're printing at 1440 dpi and you've got a four-inch-wide photo, your printer will produce that by laying down a line of dots with 1440 individual droplets of ink every inch. In your four-inch-wide printer, the result will be 5760 dots across since 1440x4=5760.

You'd think that in order to produce a beautiful picture at its best resolution, your printer would need to have a document that was 1440 dpi, but it really only needs to have a certain number of pixels to work withbetween 160 and 260 pixels per inch. That's enough for it to create a stunning photo simply by looking at the incoming picture and resampling it to its best resolution. Say that your printer creates its best images with photos set to at least 240 ppi, if you divide 1000 by 240, you'll see that the same image that was ten inches wide on the screen would come out to be about four inches wide when printed on a color-photo printer.

As long as you don't want to make a print larger than four inches, your printed images should look great coming from that two-megapixel camera. But if you try to enlarge your image and print an 8x10, you'll notice that the output looks lousy. That because when you enlarge a digital image, your computer moves each recorded pixel farther away, and then fills in the space between each pixel with guesses as to what would be there if you'd used a higher resolution camera. The result is a photo with jaggy lines and color problems.

A camera with a higher megapixel resolution can produce a larger print than one with a lower resolution, without needing to resize it. Even if you never plan to print something larger than 4x6, you should still keep your camera's resolution in mind. If you want to print just an area of your photographwhat is called a cropyou'll need enough pixels in your image so that you'll have the right amount left over when you crop out the rest of the photo.