If you use Smugmug for photo hosting, there is a gallery feature called “Sharpening” that automatically sharpens every photo that is displayed. But, there is very little instruction on what each of the four settings of this feature really mean. I’ll show you what settings I use…
My goal in this post is not to explain technically what each setting means, but rather to give you my settings that work so that you can copy them and have nicely sharpened photos on Smugmug. If you want a technical explanation, then Smugmug has help files that explain that.
Here are the Smugmug sharpening settings that I use:
- Amount: 0.300 This is 30% sharpened. 20% replicates the photo faithfully, but I want a little bit more so I go with 30%. More than this and I start to see artifacts.
- Radius: 0.500 This is just like radius in Lightroom or Photoshop sharpening. I use 0.5 because it gives finer sharpness to the edges. Also this radius is suited for monitors and that is what people will be using to view the photos.
- Threshold: 0.050 I go with the default here. This specifies how much difference there must be between pixels before they get sharpened. If an image is very noisy, then this number should be higher. But, I de-noise all of my photos before uploading, so I go with the default and it works.
- Sigma: 0.500 This is the most confusing parameter of all. In simple terms, it is a measure of how far from the center of a pixel to be sharpened that a nearby pixel can be and still have a say in the sharpening required. The basic formula is that this number should match the radius if the radius is less than 1. I have 0.5 for radius, so sigma is 0.5 also.
The sharpening is applied to photos as they are uploaded (display copies), so if you change these sharpening settings after uploading, then you have to either re-upload a photo or just rotate it then rotate it back – a trick to get Smugmug to re-generate display copies.
The original photos are not sharpened, so if they are sent to a printer they have your original sharpening and not the display sharpening that Smugmug does.
Why have this display sharpening at all? When photos are re-sized as they are when displayed on Smugmug or anywhere on the internet, they lose sharpness due to pixel convolution. Basically I think of it as pixels can’t all fit in the smaller image size, so some get shifted or on top of others, making the overall image a little more blurry or un-focused. Smugmug corrects this with the sharpening panel in the gallery settings and uses these settings to make copies that are sharper. This way, people viewing your photos will be able to see the sharpness that you see when viewing at full size, while they are viewing smaller sized photos on your Smugmug site.
Where do these settings come from that Smugmug uses? They come from a program called Image Magik. This is the code that is used on the Smugmug site.
Thank you for reading what I wrote — I hope your enjoyed it.