If you’re letting your web-based photo gallery software or service resize your image files for you, you’re wasting your time. Many of these kinds of software and services have a limit on either the number or volume of files that you may upload at once, so uploading a batch of pictures from a digital camera that weight in at 1.5 megs or more each is going to take you an unecessarily long amount of time because (1) the larger a file is the longer it takes to upload, (2) even though you have a broadband connection at home, most broadband connections download much faster than they upload, and (3) if you have a lot files you will need to split them up into smaller batches that fall under the number or volume cap set by the software or service you’re using.
ImageMagick is free software that will let you resize all of your image files yourself, quickly and easily. ImageMagick is not a suite like Adobe Photoshop; it’s a set of powerful command line tools for creating, editing and composing images. Operating from the command line means that you can issue one command and go do something else while ImageMagick churns away at a directory full of image files.
Installing ImageMagick
To install ImageMagick, visit the ImageMagick download page and pick a download. Wait for the installer to download and then double-click on it; ImageMagick will install itself. As the website says, you can test whether the installation was a success by opening up a command prompt (click Start, click Run, type cmd, press Enter) and issuing the following commands:
convert logo: logo.gif
identify logo.gif
imdisplay logo.gif
If the installation was a success, the ImageMagick logo will appear on your screen.
Resize your images
Now comes the fun part: you are going to resize an entire directory full of images with one command. It doesn’t matter how many images are in the directory. There could be hundreds, or even thousands. ImageMagick’s mogrify program will take care of them all.
First, gather all of the images you are going to resize and copy them into one folder. We say copy because the program we are about to use, mogrify, is going to overwrite the image files with the newly resized versions. If you operate on the original image files with mogrify, you will lose them.
Second, decide to what dimensions you would like your images resized. For images destined for a web-based photo gallery or even e-mail, we usually pick 500 - 600 pixels in width. We emphasize width because mogrify maintains aspect ratio when resizing images. This means that if resizing to 600×500 would distort your image, mogrify will resize to 600 pixels wide and figure out the appropriate height to keep your image looking identical to the original.
Third, start up the command line. Click Start, click Run, type cmd and press Enter.
Lastly, change to the directory containing your image files and issue the mogrify command:
cd
mogrify -resize 600×500 *
Example:
Once mogrify finishes working, you’re ready to upload.
Further reading
ImageMagick is a powerful set of programs that can do a lot more than just resize images. To learn more, start reading at Command-line Tools at ImageMagick.com.
[tags]image editing,graphics,image magick[/tags]
