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IHP related question.

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  #1  
Old 02-06-2011, 11:19 AM
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nebulaoperator nebulaoperator is offline
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IHP related question.

I have come across one image where different IHP layers have been used. They were just above the background layer.One of them was marked as IHP-IHP-75/25 and the other one IHP-45/15. I was clicking off and on to see what the change they are maiking. IHP-75/25 was taking off highlights and IHP-45/15 was altering shadows( to be more precise it was black skin).Then layers above IHP were curves. Mostly they would do again shadows and highlights tweaks on the skin. My question would be : Is this a technique something to do with D&B? What is the purpose of the inverted high pass with a different settings? Are 45/15 and 75/25 have to do with blur and high pass ratio. Thank you.
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Old 02-06-2011, 11:54 AM
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Re: IHP related question.

The inverted highpass (IHP) is surely used to even tones. The number indicate the HP and the Blur amount
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Old 02-06-2011, 01:33 PM
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Re: IHP related question.

Would you tell me why IHP and then curves has been used to tweak shadows and highlights. Isn't one of the methods suitable to do all the job? Thank you
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The inverted highpass (IHP) is surely used to even tones. The number indicate the HP and the Blur amount
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Old 02-06-2011, 01:39 PM
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Re: IHP related question.

As I do not have the PSD File, I don't know why this particular person used the curves, but I would think that this is used for pixel based D&B, whereas the IHP's are used to even the tones resp. even out transitions between highlight and shadows beforehand. It's a nifty shortcut, but of course all can be done with D&B alone!
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Old 02-06-2011, 02:41 PM
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Re: IHP related question.

As Amica said, everything could have been done with dodge & burn, but that'd have taken longer.

The reason why IHP couldn't been used all the way is that it is based on blur (averaging) and therefore not all of the changes through curves were doable with it alone (e.g. lighting an area that is between dark areas).
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Old 02-06-2011, 03:18 PM
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Re: IHP related question.

Something popped into my head Der_w. Here is the link to that PSD file by Natalia Tafarel : http://www.modelmayhem.com/po.php?thread_id=673913 She left a PSD file there.
There you'll see(if you don't mind) Low -dust & scratch layer , then above AI( what is this layer??) seems like it bringing detail back and then curves applied on the top takes the pores away. How does that AI with curves work both together? i am expanding a little bit that thread. Thank you

Last edited by nebulaoperator; 02-06-2011 at 03:29 PM.
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Old 02-06-2011, 08:15 PM
julianmarsalis julianmarsalis is offline
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Re: IHP related question.

Ask godmother herself she won't bite I think lol....
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Old 02-06-2011, 11:23 PM
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Re: IHP related question.

Nebula, The combination of Dust & Scratches and the AI (Applied Image) layer is a type of frequency separation and is a variant of the technique described in the following thread called "High Pass Sucks" at ModelMayhem. The link is here:
http://www.modelmayhem.com/po.php?th...=439098&page=1
The curve which is clipped to the High Frequency (AI) layer reduces contrast of that layer unilaterally by pinning all all of the pixels which are brighter than 128 and increasing the value of those pixels which are lower than 128, to 128. By separating the image at a carefully selected radius (in this case a low radius representing mostly the pores, what you have done is an "on mass" Dodge of the pores. You can see it better if you zoom in to 200 or 300%. If the opposite side of that curve were "grounded" or pulled to 0, the contrast would have been lowered by lowering the value of pixels > 128 to 128. The net effect would have been to burn on-mass edges below a certain radius.
This technique is clearly exponentially faster than doing a pixel by pixel D&B which can be hugely time consuming when you have an image such as this one. Like every technique that affects large numbers of pixels with the same adjustment, you need to be very careful where and how you use it.
Regards, Murray
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Old 02-07-2011, 06:48 AM
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Re: IHP related question.

I have tried ,,high pass sucks,, ans something went wrong. I have Background layer then two copies above. GB which i have tried 1.7 and then 5.1( here i am a bit confused (when suggested on ModelMayhem website) to put same input as to HP. So i have tried both. Then i went to image apply and followed all the steps to alter layer above GB, the top one. It gives me that liner light affect only. I don't know whether i misunderstand here something?!
Talking about Dust &scratches and AI(image apply) and the curves on top technique , do you know what are the settings for AI? I have tried but din't work out this time
Thank you.
Quote:
Originally Posted by mistermonday View Post
Nebula, The combination of Dust & Scratches and the AI (Applied Image) layer is a type of frequency separation and is a variant of the technique described in the following thread called "High Pass Sucks" at ModelMayhem. The link is here:
http://www.modelmayhem.com/po.php?th...=439098&page=1
The curve which is clipped to the High Frequency (AI) layer reduces contrast of that layer unilaterally by pinning all all of the pixels which are brighter than 128 and increasing the value of those pixels which are lower than 128, to 128. By separating the image at a carefully selected radius (in this case a low radius representing mostly the pores, what you have done is an "on mass" Dodge of the pores. You can see it better if you zoom in to 200 or 300%. If the opposite side of that curve were "grounded" or pulled to 0, the contrast would have been lowered by lowering the value of pixels > 128 to 128. The net effect would have been to burn on-mass edges below a certain radius.
This technique is clearly exponentially faster than doing a pixel by pixel D&B which can be hugely time consuming when you have an image such as this one. Like every technique that affects large numbers of pixels with the same adjustment, you need to be very careful where and how you use it.
Regards, Murray
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Old 02-07-2011, 07:24 AM
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Re: IHP related question.

Quote:
Originally Posted by julianmarsalis View Post
Ask godmother herself she won't bite I think lol....
I was thinking the same thing :P

This is a bit taken from the handouts I wrote for the Workshops (Might expand it into an ebook, since the DVD might be pricey for some)

IHP

IHP is something like an automatic (not as detailed and not as undestructive) way of getting tight skin and evening out the hard transitions between shadow and light, among other things, while keeping the texture intact.

What we do is retain a certain defined frequency using the high pass , blurred (for the same reason we use a soft edged brush when Dodging and burning) , inverted (to get the negative of the details light/shadow) and blended using the linear light blending mode.

This blending mode burns or dodges by decreasing or increasing the brightness, depending on the blend tone. If the blend tone is lighter than 50% gray, the image is lightened by increasing the brightness. If the blend color is darker than 50% gray, the image is darkened by decreasing the brightness.
Very much like D&B with a 50% gray layer, that’s why I call this automatic D&B


What for:

Saving time is one of the mayor advantages of this technique

• Smoothing transitions between shadow and light
• Removing Strong Highlights
• Removing strong shadows
• Flattening light – so you can introduce new highlights and also shadows by manual D&B
• Smoothing median texture
• Straightening and tightening fabrics in clothing and accessories.
• Smoothing floors, carpets, grass and any kind of textured surrounding (as long as there’s no recognizable pattern)
• Straightening hair
• Removing blotches in legs and body

Experiment with it, and will lead to a lot of other uses.
How to:

• Make a stamp ( Command(Mac)+option(Mac)+shift+E or Control(PC)+alt(PC)+shift+E)

• Find the problematic area

I found that visualizing the problem can be done using the “preview window” in the Gaussian blur filter. Simply move the slider until the problem area blends with the surrounding area. Take a mental note of that radius but make sure to chose a number that is divisible by 3 (i.e.: If the right radius is 26 then go up to 30, always round up, never down) – Once you have decided on the radius, cancel the Gblur. This is just to visualize the radius in a simple and intuitive way.

• Working on the stamp layer, go to Image/Adjustment/Brightness-Contrast and reduce the contrast to -50 making sure to tick the “Use Legacy” box. (This step corrects the base layer to apply a regular HP)
It will reduce the contrast, making it look faded. But in itself will not reduce the effect.

• Still working on the stamp layer go to Filters/Other/High Pass and insert the chosen radius (on the second step)
• Invert the stamp layer
• Run Gaussian Blur filter at 1/3 of the HP radius
• Blend it using the linear light blending mode
• Add a Mask to hide / Paint back where need it, using a big soft brush – 50 to 100% opacity (If you chose the radius correctly, 100% will be perfect)

Notes - Recommendations:

• Using a small radius to work on fine texture is highly not recommended.
• Do not use hard brushes. Do not work over edges (mouth, nose, borders)
• This technique is like drinking, a little bit is fine, but if you go overboard you end up throwing up in a corner; and that’s not attractive. ☺
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