Curves are hard to use.

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machoman
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Curves are hard to use.
5 months ago

I'm trying to use curves to manipulate contrast and find it very difficult to be successful at it. I usually use Levels but find it does destroy quite a bit of data as it cuts the shadows & highlights points. Does anyone regularly use curves to improve contrast - or do you still fall back to levels?

Technically curves has a lot of benefit but it's so hard to get a nice photo out of it.

Alpha Doug
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Re: Curves are hard to use.
In reply to machoman, 5 months ago

What program are you working in?  There are usually several different ways to accomplish adding more contrast or less to your images.  Curves is only one way, but it can be very powerful.  First, you should practice adding control points, so that you can make changes to just a small part of the spectrum.  See how moving those points changes the "range" of adjustment.  Look at what an "S" curve with a central control point does to the image.

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Babine
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Re: Curves are hard to use.
In reply to machoman, 5 months ago

machoman wrote:

I'm trying to use curves to manipulate contrast and find it very difficult to be successful at it. I usually use Levels but find it does destroy quite a bit of data as it cuts the shadows & highlights points. Does anyone regularly use curves to improve contrast - or do you still fall back to levels?

Technically curves has a lot of benefit but it's so hard to get a nice photo out of it.

And, if your curves adjustment does what you want but causes concerns in other portions of the project, fill the mask with black and apply selectively with a white brush at whatever opacity. Also, try soft light mode as a blend.

Unsharp mask, again applied selectively, will also increase contrast.

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Tom Axford
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Re: Curves are hard to use.
In reply to machoman, 5 months ago

machoman wrote:

I'm trying to use curves to manipulate contrast and find it very difficult to be successful at it. I usually use Levels but find it does destroy quite a bit of data as it cuts the shadows & highlights points. Does anyone regularly use curves to improve contrast - or do you still fall back to levels?

Technically curves has a lot of benefit but it's so hard to get a nice photo out of it.

I used to use Curves quite a lot, but there are a number of drawbacks and I have mainly switched to using the adjustments in Lightroom 5. LR provides 6 sliders for controlling the tone curve (exposure, contrast, highlights, shadows, whites and blacks) and I find these are much easier to use than fiddling with the shape of the curve myself, while giving a lot more control than Levels.

There is another huge advantage to using LR 5 (or another raw processor) in that they preserve the colours in a way that simply doesn't happen if you use Levels or Curves (assuming you are working in RGB colour space, which is usual).

By the way, you can use LR to process jpeg files, but you'll get better results if you shoot in raw and process the raw file.

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drh681
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Perhaps if we better understood what...
In reply to machoman, 5 months ago

You are trying to do we could be more helpful.

You need to understand that tone curves do not need to be the classic lazy s that pumps contrast.

Sometime you can invert that s to good effect. Or use a bow curve or a double curve.

Using layers and masks you can put different curves on different parts of an image.

The more powerful tools are in the Shadow/Highlight dialog or in Bridge/ACR

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ImageAmateur
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Re: Curves are hard to use. blend modes
In reply to machoman, 5 months ago

machoman wrote:

I'm trying to use curves to manipulate contrast and find it very difficult to be successful at it. I usually use Levels but find it does destroy quite a bit of data as it cuts the shadows & highlights points. Does anyone regularly use curves to improve contrast - or do you still fall back to levels?

Technically curves has a lot of benefit but it's so hard to get a nice photo out of it.

Along with curves /other adjustment layers, may I suggest to be judicious in what blend mode you use.

The Luminosity blend mode in Photoshop or PSP X6 will ensure that you can adjust the overall contrast without affecting color balance.

And be gentle with adjustments at first, to gauge effect carefully.

Good Luck.

PS Here is a wonderful site for an introduction into the post processing including curves. I suggest reading blend modes as well as curves, at least.

http://www.ronbigelow.com/articles/articles.htm

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machoman
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Re: Curves are hard to use. blend modes
In reply to ImageAmateur, 5 months ago

I've gone back and tried Curves again -  nah...it's not working for me. Changing the blend mode to luminosity did improve things slightly but it's still yucky. i've tried everything - using the arrows, nudging them slightly (trust me - my S curve is very very mild - anything more and it looks terrible) but still Levels wins hands down on ease of use and also ultimately the quality speaks for Levels.

extra info - i'm editing on the soft proof copy as it gives me the best paper/screen match.

I'm giving up on curve and will use Levels as my main contrast tool.

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WineO
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Re: Curves are hard to use.
In reply to machoman, 5 months ago

Levels are an axe -- Curves are an ice pick. Learn to use them correctly and you will find that you can be far more accurate than with levels but both have their place. Google some tutorials as watching these will shorten the learning curve.

Claude

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artcihoke Steve
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Re: Curves are hard to use.
In reply to WineO, 5 months ago

Some people have a problem with the concept of curves.  They are a wonderful tool, but I have been on a internet class when a smart, knowledgeable user, just could not grasp.  With a lot of patience, the user got it, but it was not easy.

Some grasp it easily, but for some it is a real challenge.  If you are a PC user, there is a plug in- Curvermeister. It works in photoshop and photoshop elements.  Try curvemeister.com  The host there is very patient.

Bottomline, LR sliders are okay for quick snapshots, but every image needs one or two passes with curves.  They can be subtle, they can sledgehammer.

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Joseph Mama
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Re: Curves are hard to use.
In reply to artcihoke Steve, 5 months ago

Bah.  I don't bother with curves as the various levels adjustments move the curve for you.  They are basically just shortcuts or macros to curve.   Contrast adjustment simply applies the S curve for you and you generally can get more granularity out of a contrast slider than you can setting curve points.

For most pictures, I believe that the sliders are perfectly fine and sufficient.  I have yet to see a picture where curves did something desirable that the sliders could not reproduce.

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Ron AKA
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Re: Curves are hard to use.
In reply to machoman, 5 months ago

machoman wrote:

I'm trying to use curves to manipulate contrast and find it very difficult to be successful at it. I usually use Levels but find it does destroy quite a bit of data as it cuts the shadows & highlights points. Does anyone regularly use curves to improve contrast - or do you still fall back to levels?

Technically curves has a lot of benefit but it's so hard to get a nice photo out of it.

I find the exposure, contrast, highlights, shadows, whites, blacks, and Clarity (midtone contrast) sliders all I need. I may occasionally run out of slider room and have to save, then reapply a second pass. Adobe has progressively improved these sliders with each new version of their Process (2003, 2010, & current 2012).

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suddie1215
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Re: Curves are hard to use. blend modes
In reply to machoman, 5 months ago

Heh... Levels are a simplified version of Curves. In fact adjustments in Photoshop like Brightness/Contrast, Color Balance and Exposure use Curves in the background (Notice that they are all grouped together in the adjustment layers palette and in the Image > Adjustments menu). They just present Curves with a different user interface that is hopefully more intuitive.

And if you think about Levels for a minute you'd understand how it is just a different implementation of Curves. The composite Levels adjustment allow you to shift tonal values within the 256 or 65,536 possible tones (depending on the bit depth of the image) by adjusting Highlights, Shadows and mid-tones (the gamma values). You do exactly the same in Curves by dragging the endpoints of the composite RGB curve to adjust Hightlights and Shadows, and the mid-point to adjust the mid-tone/gamma values.

machoman wrote:

I've gone back and tried Curves again - nah...it's not working for me. Changing the blend mode to luminosity did improve things slightly but it's still yucky. i've tried everything - using the arrows, nudging them slightly (trust me - my S curve is very very mild - anything more and it looks terrible) but still Levels wins hands down on ease of use and also ultimately the quality speaks for Levels.

extra info - i'm editing on the soft proof copy as it gives me the best paper/screen match.

I'm giving up on curve and will use Levels as my main contrast tool.

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drh681
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Re: Curves are hard to use. blend modes
In reply to machoman, 5 months ago

machoman wrote:

I've gone back and tried Curves again - nah...it's not working for me. Changing the blend mode to luminosity did improve things slightly but it's still yucky. i've tried everything - using the arrows, nudging them slightly (trust me - my S curve is very very mild - anything more and it looks terrible) but still Levels wins hands down on ease of use and also ultimately the quality speaks for Levels.

extra info - i'm editing on the soft proof copy as it gives me the best paper/screen match.

I'm giving up on curve and will use Levels as my main contrast tool.

There's the problem then.

You're working in the most confined space.

Akin to practicing Tai-Chi in a closet.

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Johanfoto
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Re: Curves are hard to use. blend modes
In reply to machoman, 5 months ago

machoman wrote:

I've gone back and tried Curves again - nah...it's not working for me. Changing the blend mode to luminosity did improve things slightly but it's still yucky. i've tried everything - using the arrows, nudging them slightly (trust me - my S curve is very very mild - anything more and it looks terrible) but still Levels wins hands down on ease of use and also ultimately the quality speaks for Levels.

extra info - i'm editing on the soft proof copy as it gives me the best paper/screen match.

I'm giving up on curve and will use Levels as my main contrast tool.

There are more ways than one to increase the contrast of an image and you have to understand the histogram before you decide what method is best. If your image lacks contrast because there are empty gaps on the left and/or right of the histogram, applying an S-curve is not the way to correct that. In that case you have to use Levels and move the left and/or right slider to the beginning of the histogram (like you probably do right now). Or do the same thing in Curves by moving the end points of the curve to the beginning of the histogram (making the curve steeper but keeping it straight). As said by others, Levels is just a simplyfied version of Curves, so anything you are doing with Levels right now, can be done with Curves as well.

If your image lacks contrast despite having a 'full' histogram however, an S-curve is the best (only) way to solve that, because using Levels would cut off (clip) pixels at both ends. That is when Curves is clearly better than Levels and why you should not give up on trying to understand it.

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NikonNature
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Re: Curves are hard to use. blend modes
In reply to machoman, 5 months ago

machoman wrote:

I've gone back and tried Curves again - nah...it's not working for me. Changing the blend mode to luminosity did improve things slightly but it's still yucky. i've tried everything - using the arrows, nudging them slightly (trust me - my S curve is very very mild - anything more and it looks terrible) but still Levels wins hands down on ease of use and also ultimately the quality speaks for Levels.

extra info - i'm editing on the soft proof copy as it gives me the best paper/screen match.

I'm giving up on curve and will use Levels as my main contrast tool.

Preparation for printing should be your last step. You should start with the original, preferably RAW, file.

If you have a RAW file, try adjust highlights and shadows in the RAW converter (2nd tab in ACR). Then when you get the image in Photoshop make a duplicate layer and do a shadow/highlights adjustments.

As someone mentioned, if the histogram shows a gap on the far left or right, then use a Levels adjustment to deal with that (but keep in mind that every image may not need deep shadows or bright highlights).

Next, if you feel it needs more contrast, then do a Curves adjustment layer. Note that you can target a specific channel (R,G,or B) with your curve. And using a mask, you can restrict how the curve is applied to various parts of the image. You can further temper the effects using the opacity slider for that layer.

There is also another more advanced technique that is worth learning, which uses Luminosity Masks. You would have to Google/YouTube it for a tutorial, but it basically calculates a range of tones - highlights, mid-tones, shadows and saves it as a channel. You can then use that channel as a pre-made mask for any adjustment layer. They work particularly well with curves. So in practice, you could create a curves layer that only targets mid-tones (for example).

The bottom line is that post processing is just like photography - you will never stop learning. Don't give up on curves, just keep trying and learn as you go.

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realgeek
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Re: Curves are hard to use.
In reply to machoman, 5 months ago

Don't use them. You can do the same thing in other ways.

Check this out:  http://scottkelby.com/2009/the-diminishing-role-of-curves-in-photoshop/

Kelby has gotten more and more strident on the issue since 2009.  Curves are the old way of doing things.  It's great for people who already know how to use it, but people who are learning photo editing now needn't bother to learn how to use it.  It's kept primarily for legacy reasons.

Even if he goes a bit too far, it's still true that you don't have to learn how to use curves any more.  You certainly can get by without it.

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ImageAmateur
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Re: Curves are hard to use.
In reply to realgeek, 5 months ago

realgeek wrote:

Don't use them. You can do the same thing in other ways.

Check this out: http://scottkelby.com/2009/the-diminishing-role-of-curves-in-photoshop/

Kelby has gotten more and more strident on the issue since 2009. Curves are the old way of doing things. It's great for people who already know how to use it, but people who are learning photo editing now needn't bother to learn how to use it. It's kept primarily for legacy reasons.

Even if he goes a bit too far, it's still true that you don't have to learn how to use curves any more. You certainly can get by without it.

The article above reads to me, that one need not use curves FOR COLOR ADJUSTMENTS as much as before, but he still uses them for tonal and contrast adjustments and indeed, does not say that they should not be used at all.

The curves tool is used much for general contrast and tonality, not just color as he is referring to in the article.

Actually, to me, at the editing stage, color should already be almost where one wants it anyway, from the initial RAW conversion and color profile.

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realgeek
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Re: Curves are hard to use.
In reply to ImageAmateur, 5 months ago

ImageAmateur wrote:

realgeek wrote:

Don't use them. You can do the same thing in other ways.

Check this out: http://scottkelby.com/2009/the-diminishing-role-of-curves-in-photoshop/

Kelby has gotten more and more strident on the issue since 2009. Curves are the old way of doing things. It's great for people who already know how to use it, but people who are learning photo editing now needn't bother to learn how to use it. It's kept primarily for legacy reasons.

Even if he goes a bit too far, it's still true that you don't have to learn how to use curves any more. You certainly can get by without it.

The article above reads to me, that one need not use curves FOR COLOR ADJUSTMENTS as much as before, but he still uses them for tonal and contrast adjustments and indeed, does not say that they should not be used at all.

The curves tool is used much for general contrast and tonality, not just color as he is referring to in the article.

Actually, to me, at the editing stage, color should already be almost where one wants it anyway, from the initial RAW conversion and color profile.

Yes, you are right.  The page I link to only speaks of color adjustments.

But, as I added, he has gotten more strident on the issue since 2009.  I can't find it in writing, but I've heard him on his show, The Grid.  (See Episode 52, starting at 36:30 -- or at 20:00, if you have the time.)  He's quite negative on curves.  It's like the darkroom -- it's obsolete.  Until recently, he used curves to add some contrast.  But with Adobe Camera Raw Process 2012 (Photoshop CS6 or Lightroom 4), the contrast slider has been improved, and he now uses the contrast slider instead of curves.

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ImageAmateur
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Re: Curves are hard to use.
In reply to realgeek, 5 months ago

realgeek wrote:

Yes, you are right. The page I link to only speaks of color adjustments.

But, as I added, he has gotten more strident on the issue since 2009. I can't find it in writing, but I've heard him on his show, The Grid. (See Episode 52, starting at 36:30 -- or at 20:00, if you have the time.) He's quite negative on curves. It's like the darkroom -- it's obsolete. Until recently, he used curves to add some contrast. But with Adobe Camera Raw Process 2012 (Photoshop CS6 or Lightroom 4), the contrast slider has been improved, and he now uses the contrast slider instead of curves.

Curves are just another tool within the 'lightroom' PP, I do not see as obsolete, one is surely working with the tonal range and contrast with whatever tool one uses, that includes curves or whatever user interface tool one uses to make it more user friendly, surely?

Each PP program has their version of bringing up highlights and shadows, changing the tonal range, most have curves and levels.

If one is comfortable with using them, fine. If not, Capture One has highlight and shadow recovery, as well as all the usual sliders, like contrast, saturation etc etc. Works well also.

ACDsee Pro has excellent  (that works very well), 'Lighting adjustments, that do the same thing, plus the usual other sliders.

But they both have levels and curves too.

Just different user interface tools.

Cant help but wonder if there is not some 'marketing speil' involved in referring to ACR Process 2012 'making curves obsolete'.... the curves just reflect what is in the image.

The sliders are just a user interface way of adjusting, surely?

I agree however, that the user interface tools in many of the programs have come a long way and are excellent.

Which is where GIMP, excellent program though it is, should look to improve i.e. user interface.

That is really all that separates it from the 'commercial' programs, they have spent some time on making the UI friendly.

Cheers.

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Johanfoto
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Re: Curves are hard to use.
In reply to realgeek, 5 months ago

realgeek wrote:

ImageAmateur wrote:

realgeek wrote:

Don't use them. You can do the same thing in other ways.

Check this out: http://scottkelby.com/2009/the-diminishing-role-of-curves-in-photoshop/

Kelby has gotten more and more strident on the issue since 2009. Curves are the old way of doing things. It's great for people who already know how to use it, but people who are learning photo editing now needn't bother to learn how to use it. It's kept primarily for legacy reasons.

Even if he goes a bit too far, it's still true that you don't have to learn how to use curves any more. You certainly can get by without it.

The article above reads to me, that one need not use curves FOR COLOR ADJUSTMENTS as much as before, but he still uses them for tonal and contrast adjustments and indeed, does not say that they should not be used at all.

The curves tool is used much for general contrast and tonality, not just color as he is referring to in the article.

Actually, to me, at the editing stage, color should already be almost where one wants it anyway, from the initial RAW conversion and color profile.

Yes, you are right. The page I link to only speaks of color adjustments.

But, as I added, he has gotten more strident on the issue since 2009. I can't find it in writing, but I've heard him on his show, The Grid. (See Episode 52, starting at 36:30 -- or at 20:00, if you have the time.) He's quite negative on curves. It's like the darkroom -- it's obsolete. Until recently, he used curves to add some contrast. But with Adobe Camera Raw Process 2012 (Photoshop CS6 or Lightroom 4), the contrast slider has been improved, and he now uses the contrast slider instead of curves.

Knowing your tools is always where it starts. It's true that there are newer tools that can be used where curves was used in the past. Color correction is a good example. I also hardly ever use curves for that. The contrast slider in ACR or Lightroom may be improved, but it still lacks the control you do have in curves, so while it may often be enough to use that slider, it still doesn't make curves absolete. The most important point in this discussion however is not only knowing when to use curves, but first and foremost how to use it.

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