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  • Chain
    replied
    Re: this frequency separation you all speak of...

    Originally posted by Godmother View Post
    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

    Leave a comment:


  • Boneappetit
    replied
    Re: this frequency separation you all speak of...

    Originally posted by John Wheeler View Post
    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 !

    Leave a comment:


  • Guest's Avatar
    Guest replied
    Re: this frequency separation you all speak of...

    Originally posted by Restret View Post
    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.

    Leave a comment:


  • Boneappetit
    replied
    Re: this frequency separation you all speak of...

    Originally posted by Godmother View Post

    Haha, Thanx Natalia, for posting the Einstein Monroe combo on your blog... Everyone should take a look... Exelente !
    Last edited by Boneappetit; 06-24-2011, 07:03 AM.

    Leave a comment:


  • Restret
    replied
    Re: this frequency separation you all speak of...

    Originally posted by John Wheeler View Post
    ...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.

    Leave a comment:


  • drode
    replied
    Re: this frequency separation you all speak of...

    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 View Post
    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.

    Leave a comment:


  • Boneappetit
    replied
    Re: this frequency separation you all speak of...

    Originally posted by P_fuzz View Post
    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

    Leave a comment:


  • Boneappetit
    replied
    Re: this frequency separation you all speak of...

    Originally posted by John Wheeler View Post
    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

    Leave a comment:


  • RobertAsh
    replied
    Re: this frequency separation you all speak of...

    Originally posted by John Wheeler View Post
    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.

    Leave a comment:


  • RobertAsh
    replied
    Re: this frequency separation you all speak of...

    Originally posted by Chain View Post
    (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 View Post
    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 View Post
    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
    Last edited by RobertAsh; 06-22-2011, 06:42 PM.

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  • Guest's Avatar
    Guest replied
    Re: this frequency separation you all speak of...

    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.

    Leave a comment:


  • Boneappetit
    replied
    Re: this frequency separation you all speak of...

    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...
    Last edited by Boneappetit; 06-22-2011, 04:41 PM.

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  • Guest's Avatar
    Guest replied
    Re: this frequency separation you all speak of...

    Originally posted by Boneappetit View Post
    ... that would be because "frequency" is an "audio term", not a painting or drawing term as far as I know, (I could be wrong thou...)
    Not used as commonly in the graphics arts field yet used often by Mathematicians, Physicists, and Engineers (may give a clue about the background of the person who came up with the technique and coined it).

    Anything that changes with regular periodicity per any parameter can be characterize by frequency. With time it is called temporal frequency, with distance it is spacial frequency and can also be used in combination of time and distance (referred to in cases such as removing falling snow in a video which changes in both time and position).

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

    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

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

    Leave a comment:


  • Chain
    replied
    Re: this frequency separation you all speak of...

    (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.

    Leave a comment:


  • RobertAsh
    replied
    Re: this frequency separation you all speak of...

    Originally posted by Boneappetit View Post
    Hi: IMHO, technically speaking Jonas is right, but I can understand why you understand it using the other terminology, and that would be because "frequency" is an "audio term", not a painting or drawing term as far as I know, (I could be wrong thou...) Like, Bass notes (low frequencies) and a flute notes (high frequencies) also like a woofer and a tweeter... and there are also the mid range tones like a tenor sax or a trombone...
    Originally posted by Chain View Post
    Yeah, the word "frequency" is more often used in relation to things like audio, and not really encountered in painting and drawing. With digital images I've only encountered it in the case of frequency separations and FFT.

    It is the correct term, although I can understand if some people like to think of it as texture/tone instead of high/low frequency.
    Exactly right. But Jonas' url has a post that explains it's not color frequency or anything like audio frequency the way I was thinking - it's spatial frequency.

    That makes perfect sense. Because you're separating your laters into:
    • Attributes that change very frequently as you pass over the surface of the image -- like tonal changes that define skin pores or hair, etc. (i.e., the frequency of change is often or high, aka high frequency items or attributes), which are typically related to texture.
    • Attributes that change less frequently -- like changes in color, highlights and shadows over broader areas like an entire face (i.e., the frequency of change is seldom or low, aka low frequency).

    Leave a comment:

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    by Caravaggio
    I like the frequency separation technique and am starting to use it and get more familiar with it. The only problem I have is where areas of extremely strong contrast meet or "edges". If I clone over those areas on the high frequency layer, it introduces a tonal change into the image when...
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  • SimonG
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  • drode
    "asymmetric" frequency separation?
    by drode
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