this frequency separation you all speak of...

[Boneappetit]

LOL Science Channel ! Cool ! One learn something new everyday... I guess part of the confusion comes with the term "Frequency Separation" itself, having this cleared up, I guess the term should be "Spatial Freq. Separation". I'm not a pro retoucher, I just speak based on my experience in music recording...

[John Wheeler]

Hi Charles (Boneappetit)
I like your expansion on the labeling - Spatial Freq Separation - SFS
If I refer to it in a post again, I will use your new coining. It will help remove confusion.

[RobertAsh]

Originally Posted by Chain

(Nobody said we separated "color frequency", although I guess we could if we wanted to).

It is indeed spatial frequency as the last post clarifies. Nice post for those who were still confused.

Thanks To clarify, the problem was not that anyone said we're separating color frequency, it's that (to me, at least) frequency in the sense of audio/radio frequency or color frequency in the sense that violet is a higher frequency wavelength of light than red is, is almost always what is meant when anyone uses the term frequency in such a term as frequency separation.


The word frequency used in the typical sense typically always refers to wavelength periodicity, and implies that the wavelengths are:

• On a monotone, gradual, adjustable, continuous spectrum of some kind (e.g. radio, audio, light waves) and...
• Are being actively originated (e.g., by a radio broadcast, loudspeaker, light source, wave machine, etc.)

Spatial frequency in the graphic arts sense (i.e., imagining oneself moving slowly over a surface like Jonas' url suggests) is quite an orthogonal way of thinking about frequency, and has quite different characteristics:

• It is not monotone - frequently occuring attributes like pores and hair are orders of magnitude more frequent than color changes across an entire face.
• It is not continuous. There are no tiny steps like 98.1 MHz then 98.3 MHz for FM radio. It more like 2 changes per linear inch on one layer (color) vs 15,000 changes per linear inch on the other layer (texture).
• It is not gradual. Otherwise we'd need 5000 'frequency' layers instead of just 2 'frequency' layers.
• Not being actively originated. Spatial frequency describes a static surface at a moment in time (at least in a photograph does), not an active streaming of waves over time.

All in all, an orthogonal usage of the term frequency, but a very nifty concept Whoever thought of it was really insightful.

Originally Posted by John Wheeler

Link on Wikipedia for spacial frequency: http://en.wikipedia.org/wiki/Spatial_frequency

Really good article, I googled it up after reading through Jonas' url.

Originally Posted by John Wheeler

And right now you may be wondering how this thread got changed to the Science Channel

You folks have to excuse John and me We get like this sometimes..... (John and I met on the NAPP forum awhile back, then we both joined RetouchPro recently). But we always try to keep it relevant and appropriate. And hopefully useful and interesting! I really enjoy the posts here and learn a lot from them, and try to give something back now and then

[RobertAsh]

Originally Posted by John Wheeler

Hi Charles (Boneappetit)
I like your expansion on the labeling - Spatial Freq Separation - SFS
If I refer to it in a post again, I will use your new coining. It will help remove confusion.

I second the motion That's an easy solution for the terminology confusion, a solution that really works well.

[Boneappetit]

Originally Posted by John Wheeler

Hi Charles (Boneappetit)
I like your expansion on the labeling - Spatial Freq Separation - SFS
If I refer to it in a post again, I will use your new coining. It will help remove confusion.

I appreciate that, John. I'm very glad to know, that my opinion can help someone else. Thanx

[Boneappetit]

Originally Posted by P_fuzz

and btw, how does it set itself appart (as a technique) from, say, DnB?

This is a good question... Not to be confused with Dog and Broom technique ! LOL

[drode]

I'm nowhere near the level of some forum members here but I use FS and D&B on most images. I have an action I run on virtually every portrait I retouch that creates FS layers in a group and a D&B (softlight) layer above. I expect to use both techniques for any retouch. They have different uses and different strengths.

Originally Posted by Boneappetit

Although the FS technique, achieves something different then D&B, as some other members stated above, most retouchers use it along with D&B. This technique is also used for some other things, like sharpening, blur, replace texture, hair retouch etc.

[Restret]

Originally Posted by John Wheeler

...Maybe a more interesting link (well for some) is how the eye's ability to recognize items of different contrast is also a strong function of spatial frequency of what you are observing. The eye's sensitivity drops off at both low and high spatial frequency (not unlike the ear with audio/temporal frequency): http://vision.psy.mq.edu.au/~peterw/csf.html

Linky no worky, at least for now.

[Boneappetit]

Originally Posted by Godmother

maybe this helps http://nataliataffarel.tumblr.com/po...ng-and-cloning

Haha, Thanx Natalia, for posting the Einstein Monroe combo on your blog... Everyone should take a look... Exelente !

[John Wheeler]

Originally Posted by Restret

Linky no worky, at least for now.

Checked the link on my original post and also in the quote on your post and both worked just fine for me at this time. Hope no others have issues with it.

[Boneappetit]

Originally Posted by John Wheeler

Checked the link on my original post and also in the quote on your post and both worked just fine for me at this time. Hope no others have issues with it.

It is working fine for me... Nice link John !

[Chain]

Originally Posted by Godmother

maybe this helps http://nataliataffarel.tumblr.com/po...ng-and-cloning

Godmother, you confused Band Pass and Band Stop in that link - at the end where you write "This is called 'Band Pass' and it has a lot of variations.". I remember confusing the two at first as well

It is "Band Stop" since we elmininate a range of frequencies and keep the rest.
"Band Pass" would be if we only "passed" one range of frequencies and removed the rest.

http://en.wikipedia.org/wiki/Band-stop_filter
http://en.wikipedia.org/wiki/Band-pass_filter