Even when you are shooting in 4K resolution on the Panasonic GH4 or Samsung NX1, for instance, applying some additional sharpening to your footage still might make sense in certain situations. Maybe you’ve slightly missed the focus in some of your shots, or intentionally you want to emphasize on certain parts of your image. Either way, using the Unsharp Mask filter may come in handy and save your work occasionally.
As-a-rule-of-thumb, you should avoid using the in-camera sharpening as in most of the time it will add too much of the effect on your footage thus introducing some unwanted texture and grain making it look too unnatural and video-ish. This, of course, is personal preference to some, as others prefer a bit of in-camera sharpening, which on the GH4 in particular is not too nasty unless you go crazy with it.
Furthermore, the in-camera sharpening will be baked in all of your clips, and you will lose the ability to fiddle the setting later in post. On the other hand, keeping your in-camera sharpening all the way down and applying the effect directly in your NLE will give you far better control over your final image.
The following tutorial produced by Casey Ferris shows how to sharpen your footage like a pro and get optimal results without overdoing the process.
The other common mistake that many unexperienced videographers and editors make is adding too much of the effect which in most of the time ruins the footage as a result. All in all, you should be very careful when using the sharpening filter as it’s easy to oversharpen your image. The first step of the process is to look for the Unsharp Mask filter in your NLE and apply it to your clip. The power of sharpening in post is actually in the three separate controls that the filters provide – the Amount, Radius and Threshold.
Generally speaking, when you sharpen an image by changing the Amount parameter, the filter takes the edge between two colors and makes the light pixels lighter and the dark pixels darker. Amount determines how light the lighter pixels get, and how the darker pixels get. If you set the amount too high, your picture will look grainy and overly contrasty.
Radius, on the other hand, affects the size of the edges to be enhanced or how wide the edge rims become, so a smaller radius enhances smaller-scale detail. A high radius means a wider area will be affected. Setting the radius too high will result in weird outlines or halos around the edges of your image.
Threshold determines how much contrast there needs to be between colors for them to be sharpened. Higher threshold values exclude areas of lower contrast. Low values should sharpen more because fewer areas are excluded. Using the threshold of the Unsharp Mask filter actually, can help you to select only those parts of the image that you really need to sharpen.
In given example Casey Ferris adjusts the Radius and the Amount settings first, and then the Threshold parameter in the end. Various recommendations exist as to good starting values for these parameters,and the meaning may differ between implementations. Generally, a Radius of 0.5 to 2 pixels and an Amount of 25–100% is a reasonable start.
Ultimately, the chances are you won’t have enough time to adjust the sharpness of every clip on your timeline. However, it’s a good practice to use the effect that you’ve already applied on one of your clips and then add it to the rest of the clips and tweak them further from that point. Last but not least, it’s recommended to apply the Unsharp Mask Filter as the very end after you’ve already colour graded your footage, thus making sure that you won’t lose any colour detail while sharpening any of your clips.