Understanding the USM

Nikolai

I am in the process of writing a review for Chapter 6 of the new edition of Dan Margulis book, Professional Photoshop, Fifth Edition. The title of the chapter is "Sharpening with a Stiletto".
While describing his techniques Dan made a huge point that sharpening, in fact, is based on blurring :huh :scratch .

I felt compelled to figure that out for myself.
The result were shocking - I could not believe I did this:



If you're interested to see how it's done - check my tutorial:
http://nik.smugmug.com/gallery/2269143

It will also become a part of my chapter review, but I wanted to share this particular piece earlier. Consider it a Christmas present :-)

HTH

CookieS

sorry , that is still way over my head.

rutt

The best part of this story is that it's called UnSharp Mask for a reason. The original technique goes way back to the early days of astrophotography. Using a literal unsharp positive as a mask for the negative produced halos and had a sharpening effect, making the stars easier to see.

The power of blurring as an element in sharpening becomes even more clear in subsequent chapters.

Nikolai

Cookie,

CookieS wrote:

sorry , that is still way over my head.

Dan's books are not "101" kinda stuff. If you're new to the whole post-processing thing, I'd suggest you start with Scott Kelby's books.
I did (a few years ago), and I am very glad I did. They let me to collect and acquire some basic knowledge and techniques so I could eventually start to understand what exactly am I doing and why. Then came Kevin Ames, then came Dan Margulis...
HTH

Nikolai

John,

rutt wrote:

The best part of this story is that it's called UnSharp Mask for a reason. The original technique goes way back to the early days of astrophotography. Using a literal unsharp positive as a mask for the negative produced halos and had a sharpening effect, making the stars easier to see.

The power of blurring as an element in sharpening becomes even more clear in subsequent chapters.

Thank you for an interesting comment.
It really bogs your mind at first, but in the end you reach the revelation :ivar

ratcheer

rutt wrote:

The best part of this story is that it's called UnSharp Mask for a reason. The original technique goes way back to the early days of astrophotography.

My understanding is that it goes back much farther than that. The Rennaisance painters (or maybe earlier painters, but I know it was hundreds of years ago) discovered that if they put a thin white outline around a dark object or vice versa, the objects appeared sharper to the eye.

If I find the reference where I learned this, I will post it.

Tim

Nikolai

Tim,

ratcheer wrote:

My understanding is that it goes back much farther than that. The Rennaisance painters (or maybe earlier painters, but I know it was hundreds of years ago) discovered that if they put a thin white outline around a dark object or vice versa, the objects appeared sharper to the eye.

If I find the reference where I learned this, I will post it.

Tim

Ages before Renaissance (at least ancient Egypt, ancient China and most likely all over the wrold) it was our beautiful better halves who discovered the beauty of the eye-liners. Same idea of introducing the local area of high contrast, but inverse: thin dark line right next to the eye's white).
Dan actually mentiones it, too:-)