Talk:Unsharp masking
From Wikipedia, the free encyclopedia
[edit] Apparent sharpness
Why is the word "apparent" used here? If you take an image and remove the high-frequency components, it doesn't just "appear" soft -- it is soft, since you've filtered out the detail. And correspondingly, if you apply an unsharp mask operator to an image, the result just doesn't "appear" to be sharp, it is very much sharp (or at least sharper), since this operator amplifies whatever high-frequency components were present in the image (proof: fourier transform the operator). mdf 22:56, 10 January 2006 (UTC)
- On the same subject, there's a small tautology in the article that ought to be removed. I edited it, but it still says
- The resulting print appears sharper than one made without the unsharp mask; the apparent accutance is increased.
- The second clause is just a restating of the first; "appearing sharper" is the same thing as "apparent accutance is increased". If someone can explain how the apparent accutance increases (i.e., how the magic trick works), that would be worth noting. +ILike2BeAnonymous 19:19, 15 October 2006 (UTC)
[edit] history
The article mentions the first use in Germany in the 1930's. Curiously, the unsharp mask operation is just a single step of the more general iterative deconvolution algorithm described by P. H. van Cittert in 1931. Is this a coincidence? mdf 22:56, 10 January 2006 (UTC)
[edit] unsharp mask creates illusion?
The intro reads: 'creating the illusion that the resulting image is sharper than the original.'. I was wondering if this is actually correct. Shouldn't it be 'resulting in a sharper image than the original but without increase of information'?
This clearly depends on the definition of 'sharper', which is in my opinion 'a more clear distinction between objects', which is exactly what the unsharpen mask does. It does not mean 'more information' I think. 71.206.215.239 01:16, 13 February 2007 (UTC)
