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Using "Blend If" for Selective Corrections.

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  #21  
Old 09-16-2004, 11:29 AM
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kiska kiska is offline
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It's rough, NOT my thing, but appropo.
kiska
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  #22  
Old 09-16-2004, 12:16 PM
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Flora Flora is offline
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WOW ... thanks Kiska!!!

...that's great!!!! ....



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  #23  
Old 09-16-2004, 03:26 PM
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Now that says it all!

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  #24  
Old 06-23-2005, 04:30 PM
hpycmpr hpycmpr is offline
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Wow!

Flora and Roger, Blend If is a topic all my $50 PS books won't touch with a ten foot pole. Thanks so much. You should seriously consider writing one yourselves. Suggested title: "PS Topics Not Found Elsewhere".

Flora, your tutorial seems to be a follow up on your Neat Image tutorial. Can you elaborate in more detail on how to apply Blend If to NI? An example will help. I assume that NI needs to be a plugin in this case?
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  #25  
Old 06-27-2005, 09:46 AM
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Flora Flora is offline
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Hi hpycmpr,

sorry for my delay in reacting ...

Quote:
Originally Posted by hpycmpr
Flora and Roger, Blend If is a topic all my $50 PS books won't touch with a ten foot pole. Thanks so much. You should seriously consider writing one yourselves. Suggested title: "PS Topics Not Found Elsewhere".
Thank you so much for your kindness!!!

Quote:
Originally Posted by hpycmpr
Flora, your tutorial seems to be a follow up on your Neat Image tutorial. Can you elaborate in more detail on how to apply Blend If to NI? An example will help.
... Originally it was ... but then I changed it to 'replacing a dull sky' .... as I thought it would be of a more practical usage ... but here is the example on using it with Neat Image ....

Attachment 1 is a cropped part of a picture taken from inside a boat ... the curtain came out nearly black when photographed against the bright light outside ...

Attachment 2 shows the curtain after I lifted the shadows in PS .... as you can see, the noise is very strong in the lightened parts, while there's practically no noise in the original lighter parts which were untouched by my 'lightening' procedure .... Before discovering what could be done with the 'Blend if' Option, I would have created a 'Shadow Mask' and denoised that only as described in the 'Using Neat Image with Selections' Tutorial .... If unhappy with the result, I would have had to repeat the whole 'denoising' procedure until I was satisfied ...

Attachment 3 shows what my picture looked like after duplicating the corrected-for-light Layer and running the duplicate through Neat Image (quite strong settings)... I was satisfied with the curtain, but the originally lighter parts of the picture had been blurred nearly beyond recognition .... That's when I used the Blend if Option ...

Attachment 4 shows the only changes I did with Blend if Option .... As you can see, I didn't change anything in the darker parts of the image since I wanted to keep the corrections done with Neat Image unchanged in those areas ... but I wanted to bring back some 'noise' and details in the originally lighter parts that's why I tweaked the right (light) sliders only.

Attachment 5 shows the end result ... The noise is balanced and I have all my details back in the originally lighter parts of my Image...

Quote:
Originally Posted by hpycmpr
.... I assume that NI needs to be a plugin in this case?
No, it doesn't .... as long as you 'place/drag' the denoised layer/image on top of your corrected-for-light one ....

There might be pictures for which the Luminosity/Shadows Masks method works better .. but with 'Blend if' you have much more control on how much of the correction done you want to have in the different parts of your picture .... I could have just as well decreased the strenght of the denoising procedure on the curtain as well by simply tweaking the left (dark) sliders ...

using the power of Blend if, you can influence the strenght of your correction on the pixels from black to white in the channels individually (Blend If Red, Green or Blue etc. Options), or together (Blend If 'Gray' Option).
Attached Images
File Type: jpg Neat+Blend.jpg (97.0 KB, 22 views)
File Type: jpg Neat+Blend1.jpg (98.2 KB, 22 views)
File Type: jpg Neat+Blend2.jpg (97.5 KB, 21 views)
File Type: jpg SNAP-0019.jpg (97.1 KB, 20 views)
File Type: jpg Neat+Blend3.jpg (98.6 KB, 25 views)
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  #26  
Old 07-06-2005, 08:28 AM
hpycmpr hpycmpr is offline
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Belated thanks

I finally got around to trying your NI blend_if tutorial, and found it working wonderfully for me. Thank you so much. May I suggest adding this last example to your blend_if tutorial so that it can help other NI users as well.

I do have some additional questions (so what's new?). Can you clarify what the blend_if split sliders do? You mentioned that the width between them controls the "transition". Is that kind of like feathering a selection? Again, an example will be great.

I noticed that the blue channel of my film scans typically has the most noise. I often wonder would it make sense to only denoise the blue channel, or to denoise it aggressively first and then followed by another round of denoising the composite channels. This should work particularly well for images with a clear blue sky. Since NI does not work in rgb, I have not been able to try either approach. I have tried blend_if the r and g channels instead of gray to denoise only the b channel, and it seems to work. Are there better ways to do this?
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