Only one thing annoys me more than uncompressed images and that’s SPAM!

A decent digital camera is cheap these days. Just about everyone owns one. Unfortunately, not everyone understands that a 2 Megapixel jpeg weighs in at about half a megabyte. Don’t get me wrong, I like when people send me big files to work with but having 45 half-meg pics on a web page all shrunk down to size using height and width attributes is nothing but annoying, even with broadband. That’s not to mention those that use these gigantic files as an avatar on their favorite forums.

Speaking of forums, those that allow image uploads really get abused by these guys. Come on, people, let’s compress and resize those images and treat your favorite forums better. Bandwidth isn’t free, ya know?

OK, so let’s get down to business. I use Adobe Photoshop so I’ll show you how to get those images down to size the way I do it.

Step one - Crop and Resize

Don’t use height and width attributes in your image tags to resize your images. Make the picture the size you need it to be. This is the number one way to reduce image size and bandwidth use.

Here is my test image [edit - test image removed because some morons were hotlinking to it] weighing in at 796kb straight from my 2.2 Megapixel Kodak DX3500 (which exports jpegs at 230 pixels per inch). Computer monitors usually show information at 72 pixels per inch so that is how I set all of my images.

I am going to open it in Photoshop and crop out any parts I don’t want to show in the final product and then go to the Image menu to “Image size…” and change this:

to this (notice the resolution):

resulting in this:

which is a 288kb file. Much better but not good enough.

*Note - If, after resizing your image down to size, the image looks jagged and unnatural, then undo the resize (in the edit menu) and then apply a little bit of Gaussian Blur in the Filters menu and then resize it. Who knew blurring an image can make it look sharper when you shrink it down?

Step two - Compress

Next I use the “Save for web…” item in the File menu.

and simply set it to “Medium” under the presets (for jpegs).

Now if you are going compressing a logo or similar graphic (not a photograph) with only a few colors or large spots of a single color then a gif will serve you much better. If you need color matching you don’t want to use jpegs because their compression is based on throwing out some information to get the files smaller. Some of that information is color information and a jpeg over a gif background will sometimes not match but the differences will only show on certain platforms using certain browsers.

After compressing my picture this is the result:

coming in at tidy 28kb. That’s about a 90% savings in file size from the resized and over 99% savings in file size from the original.

So, come on, people! Let’s compress those images and save the bandwidth!

This entry was posted on 27Dec05 @ 2140 and is filed under Web standards. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.