Sharpening for the Web

Here is something that I've known about for some time, put it on my list of things to learn and do, but haven't taken the time to just do it until now...sharpen my images for the Web.

Some of us, me included, don't post SOTC (straight out of the camera), full-size images on the Web. That means you have to resize them using Photoshop, Lightroom, or whatever your image editing software of choice is. Resizing an image also means resampling the image from one dimension to another, say 2832x4256 (12MP) to 683x1024. When you resample an image this way, that is downsampling, you are reinterpreting the pixels and you are losing data! There's all sorts of names for the phenomenon that goes on when you do this, ringing, aliasing, blurring, artifacts, etc. There are also all sorts of algorithms that can be used to resample your images and each has a pretty significant impact on the quality of your image.

I won't go into a a long technical discussion about resampling algorithms and sharpening algorithms. You can read up all about them on the Web if you are interested. Instead i'll just show you a workflow that I'm using now that creates great looking images from your full-sized images for the Web. Perfect for Facebook, Flickr, Tumblr, and the like.

1. After you prepare you image and have completed all your post processing, export or create a full-sized JPEG of your photograph. Then open the JPEG in Photoshop. Here is the original, full-sized JPEG of the image I'll be working with here (Click on the image to see it full-size).

2. Resize your image to your new dimensions. Here I am sizing this to 683x1024 for the Web. Select Bicubic Sharper (Best for reduction) for the resampling algorithm.

3. Now that your image has been resized and resampled, it's time to apply some more sharpening to try to reel in some of the detail that has been lost. For this I use the Unsharpen Mask... Filter. I typically try amounts from 200% to 400% and a radius of 0.3 pixels and leave threshold at 0.













4. Now your image is ready for the Web!


Here's a comparison between the unsharpened image and the sharpened version after resizing the images. Roll-over the image with your mouse to see the sharpened version.

These images are zoomed at 300%. Notice the difference in texture of the football and the sharpening and detail in the face. While there are some visible artifacts in the sharpened version, remember we are viewing this image enlarged at 300%. At 100% you won't be able to see these (see the next image below).

roll-over with your mouse to see the sharpened version

Here are the two final images, again for comparison, now at just 100%. Roll-over with your mouse to see the sharpened version.

Can you spot the artifacts now? I don't think so.

Which one looks better? The sharpened version if you ask me.

This is my nephew btw. I can see much better detail in the football, his face, his hair, his tattoes, his shirt, and his pants. The overall effect isn't obviously noticeable but it results in a better looking image. Isn't that the point? So now you can create great images for the Web and have everyone envious asking "how do you take such great photos?"

roll-over with your mouse to see the sharpened version