I am using the
convert tool from the ImageMagick package to create the web versions of my photos. So far I have used something like
convert -resize 1024x1024 for web versions and
convert -resize 300x300 for thumbnails. However, many people seem to prefer adding a little bit of sharpening after resizing, and hence I have started to experiment with the -unsharp option.
We have an excellent answer on this site that explains the parameters of the "unsharp mask" tool and gives some recommendations of reasonable values for web use. However, one of my problems is that the unsharp mask option in ImageMagick seems to be somewhat different from the unsharp mask filter in Photoshop or GIMP.
Hence the question: What are the recommended parameters of the
-unsharp option in ImageMagick for web use?
I am looking for "harmless" settings that I can safely use in bulk conversions, without any significant risk of creating visible artefacts (e.g., halos). Of course for optimal results I would have to manually fine-tune the settings for each photo, but I am interested in a quick solution that I can use for a large bunch of photos.
Right now I am using the following values (which may or may not correspond to something like radius = 0.5, amount = 50%, threshold = 2):
This seems to give reasonable results. The effect is very slight; it is barely visible in many cases, and it seems to be non-distracting in all photos that I have tried so far. Nevertheless, it helps a bit. But the question is: could I do better? What are your favourite values of these parameters?