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Contrast Grading Theory


This video shows the theory of contrast grading.

You can buy the Contrast Grading 2nd edition tutorials.



]Purchase Page


---
"After that shutter closes it’s all over. The physical light captured on film is all that is left, a history of light preserved in chemical form, and I have to move on to the next one."

http://martinhensonphotography.co.uk
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Re: Contrast Grading Theory


very interesting what you say about CM versus BW converstion

makes me want togo back to CM conversions but- don't you just use the desat slider?

Doesnt that not lose the CM advantage you mentuion here in sharpness?

---
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That's a part of what I seem, but not apart from what I am

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Re: Contrast Grading Theory


I would not recommend you desaturate to -100 if your original image is derived from an RGB file unless all you need to do is remove colour from the image.

Its all about the collision of the three channels, R G B and the way which you collide these channels will give you greater control of both tonality and luminosity.

The Contrast Masking approach will work better if you start out with the best colour file you possibly can and in some cases this may mean increasing colour luminosity with adjacent colours as this will give you greater separation on tonality for when you start to use the Contrast Masking tools.

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Re: Contrast Grading Theory


quote:

IanBarber wrote:

I would not recommend you desaturate to -100 if your original image is derived from an RGB file unless all you need to do is remove colour from the image.

Its all about the collision of the three channels, R G B and the way which you collide these channels will give you greater control of both tonality and luminosity.

The Contrast Masking approach will work better if you start out with the best colour file you possibly can and in some cases this may mean increasing colour luminosity with adjacent colours as this will give you greater separation on tonality for when you start to use the Contrast Masking tools.



Sure - but i the example above , you would already have done that in LR or ACR wouldn't you before bringing into photoshop

But my question really was concerning the difference in sharpness, not contrast, between the different methods Martin shows in his video

It appears that the CM method gives a sharper starting point than the BW filter in ps

I'd love to see a similar comparison done between images opened in Ps and those prepared with te various methods in LR

e.g. would there be a difference betweenusing the BE conversion in LR and desaturating in LR in apprarent sharpness


I imagine that shift in Ps in sharpness between the two methods was due to the same effects to some degree that yu'd get if you upped the green too much or loweredthe blue to much - it appears to lose sharpness in the image

Anyway - point being - we spend a fortune and expend loads of effort to get resolution and sharpness, well, if it's being sloughed off at the outset then were not doijg ourselcves any favours, so IF the initial conversion to BW method has a part to play in this then we need to explore it in depth


---
I am a part of what I am, not apart from what I dream,
That's a part of what I seem, but not apart from what I am

~ Simon
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Re: Contrast Grading Theory


i am wondering if you are referring to position 6:30 in the video.

The shadows on the leaf on the right hand image are going to be darker because a curves adjustment was applied to it and the curve was pulled down so all the darker values by default would have become darker.



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Re: Contrast Grading Theory


quote:

IanBarber wrote:

i am wondering if you are referring to position 6:30 in the video.

The shadows on the leaf on the right hand image are going to be darker because a curves adjustment was applied to it and the curve was pulled down so all the darker values by default would have become darker.




4:47-5:15 approx

he's talking about SHARPNESS

Last edited by Digital Finger, 13/Sep/14, 10:15 am


---
I am a part of what I am, not apart from what I dream,
That's a part of what I seem, but not apart from what I am

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Re: Contrast Grading Theory


I am not sure how or why a conversion from Colour to Monochrome can change sharpness.

The only thing that I can see having looked agin at the video is perceptual sharpness.

Because a curve adjustment was made on the right image and that curve was pulled down, perceptually, the edge contrast of the leaf may appear to look sharper due to the shift in contrast.


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Re: Contrast Grading Theory


what does Martin have to say about it?

---
I am a part of what I am, not apart from what I dream,
That's a part of what I seem, but not apart from what I am

~ Simon
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Re: Contrast Grading Theory


Well the images where both put into PS, I did not do any adjustments only ticked the conversion boxes in the Black and White conversion and Channel mixer, the Channel mixer did visually look sharper on screen.

Maybe it because the Black and White conversion tool uses different logarithms and all the channels, however I cannot confirm that.


---
"After that shutter closes it’s all over. The physical light captured on film is all that is left, a history of light preserved in chemical form, and I have to move on to the next one."

http://martinhensonphotography.co.uk
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Re: Contrast Grading Theory


quote:

martinimages wrote:

Well the images where both put into PS, I did not do any adjustments only ticked the conversion boxes in the Black and White conversion and Channel mixer, the Channel mixer did visually look sharper on screen.

Maybe it because the Black and White conversion tool uses different logarithms and all the channels, however I cannot confirm that.



Ihave been doing some tests and certainly think that the contrast appears different which might explain it but will also try some moreexacting tests

---
I am a part of what I am, not apart from what I dream,
That's a part of what I seem, but not apart from what I am

~ Simon
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