Problem : Solution Improve blurring in compressed web images

Problem: The Blur option in the Save For Web dialog box produces less than stellar results

Solution: Use selective blurring.

Image compression can be a tricky thing; after all, you want the best quality and the lowest file size possible. That alone is a contradiction in terms. However, people do it all the time using various techniques. Granted, blurring an image isn't usually the way to go, but depending on the image, it can be a legitimate solution to reducing the size of a file. Let's take a look at a great built-in feature Photoshop has for saving web images: the Save For Web feature.

Looking at the Save For Web feature

With the Save For Web feature, located in the File menu, you can compress an image for the web with a great deal of control. This feature allows you to compare multiple compression settings in one dialog box. To use the Save For Web feature, open an image you want to compress. Then, choose File Save For Web to open the Save For Web dialog box, which shows four versions of your image. (If this preview window isnt showing, click on the 4-Up tab.) From here, you can adjust the settings of your image to create your final compressed image. Choose from high, medium, and low JPEG settings in the Saved Sets Of Optimization Settings dropdown list to preview how these settings will affect your image.

The Preset (Settings) section of the Save For Web dialog box also has a Blur option. You can use this to apply a Gaussian-type blur over the entire image, which helps reduce the artifacts that can appear around sharp lines. The Blur option has a range of 0 to 2; Adobe recommends a setting of 0.1 to 0.5 if you need to use it. Blurring your image reduces the file size without applying more compression. This can be a good thing or a bad thing.

Our Problem image shows our image with the maximum Blur amount at a JPEG High quality setting. As you can see, all elements in the image lose detail, while we'd prefer that the boat stay in focus. So, in general, we recommend staying away from using the Blur option or only applying the slightest amount. You're better off applying more compression. However, if you want to try using a blur, we have another suggestion.

Applying selective blurring

Rather than applying the Blur option in the Save For Web dialog box, you should apply a blur directly in Photoshop. For example, we selected everything in the image except the boat, and then we applied a Gaussian Blur with a Radius of 1.5. This keeps the boat in focus and allows the background to blur. We then chose File Save For Web. The resulting high-quality JPEG file size, shown in our Compression at its finest

Compressing images is a little easier when you use the Save For Web feature. This feature offers some of the most sophisticated tools available on the market. Depending on your image, you may also want to experiment with the blur factor.