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

TIP: Using your pop-up flash as a commander

I recently got to see Joe McNally and David the Strobist Hobby in action when the Flash Bus Tour stopped in Philadelphia. Man, they make things look so easy. It was an amazing time to see these two pros and living legends in action.

Joe McNally is a big proponent of Nikon CLS/i-TTL, so he's been using an SB-800/900 Speedlight or even the pop-up flash as a commander. No news here right? We all know as well that you can set your Speedlight so that it does NOT contribute to the exposure of your scene. But it will still produce some visible light via the pre-flash that can land you in a snafu because you've got a "blinker" on your hands. What's the alternative? Radio triggers? SU-800 since it's IR and not visible light? Remote cord so your commander is off-axis and not going to be in your subjects direct line of vision? All good options. But what about if you are using your pop-up flash as a commander and that's all you've got?

Electrical tape.

Just grab a small bit of electrical tape and cover up your pop-up flash, not entirely, but enough that it hides the direct visible light that would usually fire directly into your subjects eyes and thus cause them to blink. For me on my D700, the tape acts like a curtain and light spills out the sides and bottom from behind the tape and this is what allows you to still trigger your Speedlights. I've successfully tested this, indoors, in a variety of situations. Just as long as you get the sensor on the Speedlight to point towards you, it works.

I'm sure there are situations that this would inhibit things and outdoors could be out of the question for this but its a cheap alternative to the other more costly alternatives.