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Increasing the Setting for Contrast
  
 
gschlact
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p.1 #1 · p.1 #1 · Increasing the Setting for Contrast


First let's not debate raw vs jpg in this thread.

1. My first question and area of confusion is what do Pros mean when a suggestion is made to increase contrast? (And the relevant change in the setting necessary to increase contrast)
2. Is this one of those questions /answers that are inconsistently used in forums?
3. Is it like when people indicate a photo is a 30% crop and we are left wondering whether it is the remaining 30% of he original image, or whether he cropped off 30%, and is it a percent of area or linea dimension etc ?

I ask for the following reason and underlying point of confusion ...
When increasing the contrast setting in camera, the brights and darks get pushed toward the edges of the histogram. Thus the slope of the histogram flattens and perceptually to our eyes makes the image 'opens up' and look like it has Less contrast. I have questioned this adjective of Less contrast especially when we increase the Setting for contrast. However, in Lightroom and other tools, increasing contrast or boosting it does the opposite and increases the slope of the histogram by eliminating gradient at the bottom and top of the histogram. (Flatter left and right sides.)
4. So why does it seem that the verb of increasing or decreasing the Setting for contrast has opposite meaning than the Adjective of the resulting contrast?




Sep 23, 2017 at 02:56 PM
snapsy
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p.1 #2 · p.1 #2 · Increasing the Setting for Contrast


The histogram grows wider when you increase contrast because it depicts tones for the entire image, without regard for whether those tones are spatially near each other in the actual image.


Sep 23, 2017 at 03:16 PM
gschlact
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p.1 #3 · p.1 #3 · Increasing the Setting for Contrast


Snapsy,
I agree and described the same thing.
Yet Lightroom does the opposite when we boost or increase contrast which often helps the localized contrast and perception. Thus seemingly opposite descriptions / results.



Sep 23, 2017 at 03:32 PM
snapsy
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p.1 #4 · p.1 #4 · Increasing the Setting for Contrast


gschlact wrote:
Snapsy,
I agree and described the same thing.
Yet Lightroom does the opposite when we boost or increase contrast which often helps the localized contrast and perception. Thus seemingly opposite descriptions / results.


When I increase contrast in LR I see the same expected behavior on the histogram - it grows wider. Perhaps we're not on the same wavelength on exactly what's being discussed. Can you describe what you mean in different terms?



Sep 23, 2017 at 06:44 PM
gschlact
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p.1 #5 · p.1 #5 · Increasing the Setting for Contrast


Snapsy,
I appreciate the dialog..,,
So I also see the edges gaining more pixels toward black and the other end white with Increased contrast. For a moment, take this to the limit where any pixel is either black or the brightest possible. Theoretically this is the Most possible Increase of Contrast. Right? But now let's back it off a bit and say we needed to critique the image. We know visually we need to imply to 'open up' the shadows and close down at the whites to provide More Shading levels. Based on this discussion we would say that they need to decrease the contrast setting. However, I contend On the forums many people would suggest to increase the image contrast to get the additional sharing levels, which you and I now agree is incorrect terminology. But, don't you agree that many people do Incorrectly suggest to Add Contrast to 'open up the image?'



Sep 24, 2017 at 06:58 PM
RustyBug
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p.1 #6 · p.1 #6 · Increasing the Setting for Contrast


Can't say I've heard anyone express "Adding Contrast" to "open up the image" in respect to opening up the shadows.

About the closest I've heard would be that "Adding Contrast" gives the image "more pop".

I really don't know of this being a common issue as you suggest.

BTW ... any particular reason why a photographer in Chicago would have your FM www go to Condo Rentals in Colorado?



Sep 24, 2017 at 08:10 PM
dgdg
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p.1 #7 · p.1 #7 · Increasing the Setting for Contrast


I don't routinely see people on FM making these kinds of comments. Maybe I've missed the threads you have in mind.

There are several main ways, in LR for example, to adjust the emphasis of light and dark in an image globally, each with their own effect. They are expsoure, white point, black point, shadows, highlights, and contrast. Similar effects are accomplished with levels, curves, and exposure blending. I think you just have to become used to these tools and then decide how to achieve the final results you desire.



Sep 24, 2017 at 08:37 PM
Milan Hutera
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p.1 #8 · p.1 #8 · Increasing the Setting for Contrast


Not sure about the theory of contrast. If you want to increase the contrast, play a bit with contrast slider. Usually this way is more subtle, unless you go for some crazy numbers like 50-60 or 100. Sometimes they are needed though. If you want do boomify the photo more, play with the tone curve drop down menu and increase the curve from linear to medium contrast. Usually, I change the curve to this setting, but sometimes it is too heavy handed, so I leave it to linear and play with the contrast slider instead.


Sep 24, 2017 at 08:46 PM
gschlact
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p.1 #9 · p.1 #9 · Increasing the Setting for Contrast


I understand fully all the tools and adjustments to edit the photo to achieve processed results. This thread questioned the language used to describe or suggest a change in the look of a photo versus the adding or subtracting of the Contrast Setting. Again, I reference and example where the shadows are too closed and hence all very dark, by our terminology this is actually too much contrast and needs to be reduced to provide more levels or steps in the shadows. Doesn't it seem a bit counterintuitive that Less contrast would provide More detail as shadows open up.

@Rustybug where are you seeing my rental URL, I know my Smugmug icon shows under my profile detail in the left for my photography. At one point I was probably trying some SEO and adding inbound links for that site.



Sep 24, 2017 at 08:59 PM
jcolwell
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p.1 #10 · p.1 #10 · Increasing the Setting for Contrast


gschlact wrote:
...Doesn't it seem a bit counterintuitive that Less contrast would provide More detail as shadows open up.


Not at all. That's why I used Astia for landscapes, in low contrast situations. Tons of detail.



Sep 24, 2017 at 09:04 PM
 

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gschlact
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p.1 #11 · p.1 #11 · Increasing the Setting for Contrast


Jim- the counterintuitive part is because the human brain has increased sharpness perception etc via Increased edge contrast, yet global contrast Reduction, Increases perceivable detail by opening up the shadows and closing down the whites for more levels/shades


Sep 24, 2017 at 09:16 PM
RustyBug
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p.1 #12 · p.1 #12 · Increasing the Setting for Contrast


gschlact wrote:
@Rustybug@ where are you seeing my rental URL, I know my Smugmug icon shows under my profile detail in the left for my photography. At one point I was probably trying some SEO and adding inbound links for that site.


Your WWW button.



Sep 24, 2017 at 09:17 PM
jcolwell
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p.1 #13 · p.1 #13 · Increasing the Setting for Contrast


I'm just saying that I don't find it to be counter-intuitive. Everybody doesn't have the same intuition about any given situation, regardless of expectations.


Sep 24, 2017 at 09:23 PM
snapsy
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p.1 #14 · p.1 #14 · Increasing the Setting for Contrast


gschlact wrote:
Doesn't it seem a bit counterintuitive that Less contrast would provide More detail as shadows open up.

Contrast adjustment stretches tones around a median point, making tones lighter than that point lighter and tones darker than that point darker. With that established I think it becomes clear that less contrast will "open up" the shadows.

Many times I'll use a global contrast adjustment to stretch the tones, then use an antagonistic adjustment to pull in one end of that adjustment. For example, I'll use contrast to make the lower midtones and shadows richer but then reduce the highlights to bring that end of the tone back down to where it was before the contrast adjustment.


Edited on Sep 24, 2017 at 09:35 PM · View previous versions



Sep 24, 2017 at 09:35 PM
RustyBug
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p.1 #15 · p.1 #15 · Increasing the Setting for Contrast


gschlact wrote:
Jim- the counterintuitive part is because the human brain has increased sharpness perception etc via Increased edge contrast, yet global contrast Reduction, Increases perceivable detail by opening up the shadows and closing down the whites for more levels/shades


+1 via increased contrast

If the shadows are too blocked up, then there is NOT enough contrast between values to be detected. By "opening up" the shadows, we are making the (shadow) values farther apart from each other (yet, closer to the whites on an absolute value) ... i.e. creating detectable difference (contrast).

Reducing the contrast is reducing the operand against the values (0-1)

If we have have values of:

.1, .2, .3, .4 and .5 and apply an (easy math) operand of ^2 (diff method's / diff operands), then the resultant is .01, .04, .09, .16, .25 for a total range of .24 variance.

If we reduce the operand back to ^1, we get our original values of .1 - .5 for a total range of .40 (i.e. more difference). Something in between, yields something in between.

Since we start off with values between 0-1, and our limits remain 0-1, the mathematical formulas operate on decimal values a bit differently than we tend to associate when we think of values on the 0-255 scale.

Adding contrast is in essence changing the operand value (the formula is a not quite this simplistic) that drives those numbers below .5 downward, and those numbers above .5 upward.

So, while the global application of the higher operand value will drive the sub .5 and the super .5 values farther apart like a wedge, the operand within the subset will drive those values closer together (thus lesser contrast allows them to remain farther apart to afford sufficient variance for detection).

I probably stated it awkwardly, but the math is applied to decimal values is why we can have less contrast = more detail ... where too much contrast can "cram" everything together so tightly you can no longer tell the difference, even if it is still driving your shadows farther from your lights.


HTH


P.S. Yeah, what Snapsy said (i.e. the midpoint fulcrum)



Edited on Sep 24, 2017 at 09:51 PM · View previous versions



Sep 24, 2017 at 09:35 PM
Herb
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p.1 #16 · p.1 #16 · Increasing the Setting for Contrast


verbs? adjectives? At my age I have forgone even caring about what those words mean.......


Sep 24, 2017 at 09:46 PM
gschlact
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p.1 #17 · p.1 #17 · Increasing the Setting for Contrast


RustyBug wrote:
+1 via increased contrast

If the shadows are too blocked up, then there is NOT enough contrast between values to be detected. By "opening up" the shadows, we are making the (shadow) values farther apart from each other (yet, closer to the whites on an absolute value) ... i.e. creating detectable difference (contrast).

Reducing the contrast is reducing the operand against the values (0-1)

If we have have values of:

.1, .2, .3, .4 and .5 and apply an (easy math) operand of ^2 (diff method's / diff operands), then the resultant is .01, .04, .09, .16, .25 for a total range of .24
...Show more

So based on your explanation, isn't my OP premise correct regarding Feedback Terminology on the forums being confusing?....
when indicating more contrast is needed in a photo (improved perception needed) to improve some of the subtle detail is a localized "increase" of Contrast using a decreased global contrast value, to spread he localized values apart increasing contrast. (head spinning) Hence my original description of inconsistent or maybe better said, incomplete wording ie: missing the word Localized when saying increase contrast within the shadows. I understand his dispite spinning head and reassure my premise of somewhat confusing feedback terminology. YET all the while some feedback is spot on when you actually want darker darks for global contrast increase that sometimes produces localized contrast increase as well. Dohhh!



Sep 25, 2017 at 12:56 AM
dgdg
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p.1 #18 · p.1 #18 · Increasing the Setting for Contrast


I just move all the sliders around and it seems to work out ok.


Sep 25, 2017 at 01:07 AM
RustyBug
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p.1 #19 · p.1 #19 · Increasing the Setting for Contrast


gschlact wrote:
So based on your explanation, isn't my OP premise correct regarding Feedback Terminology on the forums being confusing?....
when indicating more contrast is needed in a photo (improved perception needed) to improve some of the subtle detail is a localized "increase" of Contrast using a decreased global contrast value, to spread he localized values apart increasing contrast. (head spinning) Hence my original description of inconsistent or maybe better said, incomplete wording ie: missing the word Localized when saying increase contrast within the shadows. I understand his dispite spinning head and reassure my premise of somewhat confusing feedback terminology. YET all the
...Show more

I think you're trying to make something out of something into something that's the same as something else.



Sep 25, 2017 at 01:22 AM
gschlact
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p.1 #20 · p.1 #20 · Increasing the Setting for Contrast


Nahhh. Really I was just confirming my understanding and sanity. :-)



Sep 25, 2017 at 02:29 AM
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