Let's look at a few examples of this. Note that my images are actually being converted to GIF (Graphics Interchange Format) images for display on the Web, which is lossy in its own way. Normally, you probably wouldn't convert JPEGs to GIF for Web display, but our journal production system requires it. As a result, you're going to be seeing a somewhat exaggerated view of the lossitude (not a real word) of these examples.

First, let's look at Figure A. This is a crop of one of my photographs of Sean, a very nice young model. As you can see, there's very little artifacting in the image, because it was saved at high quality.

FIGURE A

There's very little artifacting when saved at high quality.

Next, let's look at Figure B. This was saved as a low quality JPEG before being converted to GIF. You can see there's a whole lot of artifacting in the image.

FIGURE B

When saved at low JPEG quality, the image gets choppy.

Finally, let's look at the full image in Figure C. This image, saved as a high quality JPEG takes 73K. When saved at low quality, it takes 25K. By the way, the original of this image, in Photoshop and uncompressed (and at a much larger size than 381x480 pixels, took 29 megabytes.

FIGURE C


Here's the full image. The excessive whiteness on her forehead and arm are the result of the JPEG translation to GIF; another reason why you need to be aware of formats. Roll over picture for a larger image.

Wrapping it all up
So, what does all this mean? Here's a quick recap:

• Generally, it's better to have a starting image that's been saved in a lossless format. That way, you have all the detail possible to work on the image later.

• Saving in a lossy compression format like JPEG works, as long as you don't get too carried away with the compression settings.

• The more you try to compress, the less you'll like the results.

• Try to find camera that has different compression modes as options, so that you can have lossless compression if you want it.

• That said, cameras that save JPEGs are fine, as long as they don't overcompress.

• Lossless and lossy are funny words.

Take care and I'll see you next week!