ImageMagick, Part Two
More about a sophisticated package of tools for creating and editing high-quality images.
Thursday, August 31st, 2006
Last month’s column introduced ImageMagick (IM), a command-line tool that’s adept at converting images from one format to another. (In fact, that’s why its main program is named convert.) But IM is well-suited to other image manipulation tasks, too. You saw some of those additional capabilities last month. This month, let’s dig in and discover even more.
File Formats Revisited
Last month’s “Power Tools” looked at the differences between the
PNG, JPEG, GIF, and
TIFF image file formats. If you’re planning to spend a considerable amount of time working with images and want high quality, there’s a lot to know. Anthony Thyssen’s Web page, “Common Image File Formats” (
http://www.cit.gu.edu.au/~anthony/graphics/imagick6/formats/) is an excellent place to start. The page discusses formats and how IM handles them.
Most image file formats store more than pixels (or vectors). For instance, your digital camera likely stores a lot of EXIF data along with the image. This data can include the date and time you took the photo, camera settings, and more.
When you edit an image, this metadata may or may not be preserved. An image editing program might also preserve data that becomes misleading — for instance, by not revising the “image generated” date to the time you converted the image.
