Resampling an image

The maximum size of your image is set by your scanning resolution, or camera capture size, in megapixels. Lower pixels per inch (ppi) means lower quality image, of course, but a larger picture. I like to think of resolution as a window screen. Stretch it, and each square gets bigger and courser. Shrink it (if that's possible with screen, try it sometime), and each square gets smaller and finer.

You can stretch your pixellated window screen to whatever size you want, to resolution, and therefore quality, will get worse and worse. But there is a solution! Resampling! Sort of. Photoshop will use an interpolation algorithm (I just copied that, I know nothing about what it means) to create new pixels to fill in blanks as the picture is stretched. What's put in there is based on what was there already, the program's best guess as to what it should look like presuming past is prologue.

Normally you don't want to resample an image, because it does affect quality. But then again, sometimes you do.

1. From the Image pull-down, choose Image Size.

2. Toggle off Resample Image. Note that the Pixel Dimensions area greys out, making no changes possible. Why. Because without Resample, you can't manufacture (or remove) pixels. You've got what you've got, so what's left is to...

3. Change the resolution. Note that the higher the resolution, the smaller the photo. You'll need to know that as a photojournalist resizing photos for publication, because resolution affects published photo quality far more than it does on a photo for the net.

4. If you can't get a photo the size you want at the resolution you want, Resample-Person to the rescue! Set the resolution you want.

6. Toggle on Resample Image.

7. Select the Document Size you want. Note that the pixels will change, indicating that Resample-Person is planning to get to work making new bits and bytes.

8. Change the Resample Algorithm if you want. I choose Bicubic Smoother only because I read it works good if you're enlarging photos.

9. Let 'er rip. Note: Image quality is better if you resample at 10 or 15 percent intervals, rather than doing one big blow-up.

10. Just so you know, you can bring a really big image to Kinko's or other copy shops, and they'll make a poster of your very own photo. Cost about $30.