Join Tim Grey for an in-depth discussion in this video The S curve, part of Photoshop: Curves (2010).
Even if you've never used curves before, if you had any exposure to Photo Shop,you've probably heard of the S curve. The thruth is, an S curve will improve just about any image because it enhances the overall contrast and contrast is generally perceived as a good thing for a photo. The s curve is named because it resembles the letter s, albeit an s that has been straightened out quite a bit. Let's go ahead and create an s curve, and then examine exactly what is happening to the image as a result. In most cases, when I'm applying a general s curve, I'll start by adding an anchor point about 20% of the way in from the black point.
I'll simply click and drag downward at that point, to darken up mostly the shadow areas of the image. I'll then move to 20% in from the white point, and click and drag upward, in order to brighten the brighter areas of the image. It's obvious just from looking at the image that contrast has been increased. The darks are a little darker, and the brights are a little brighter. Let's take a look at exactly what's happening within the curve. The mid-tone region, the central area of the curve has been increased in steepness, which means we're increasing contrast for those mid-tones. But then the curve tapers off and actually the end points of the curve, the highlight range and the shadow range, are less steep than the original curve. That means we've actually reduced contrast in the darkest shadows and the brightest highlights.
You wouldn't normally think that you want to reduce contrast, and really, I don't think of this as reducing contrast in any area of the image. Rather, I think of it as tapering off my increase in contrast so that we're not sacrificing shadow or highlight detail in the process. This is one of the things that makes curves tremendously better then the levels adjustment. With levels the only way we can increase contrast is to bring in the black or white points. Bring those black or white points in too far, and you're losing detail in the image.
With an S curve, we can increase contrast without sacrificing any inforamtion at all. Nearly every image I have ever adjusted in Photoshop gets some form of an s curve applied to it. Quite simply, just about any photograph will benefit from at leas a slight increase in mid-tone contrast. And the s curve provides that mid-tone contrast, without a loss of highlight or shadow detail. The s curve really is a beautiful thing that can add to the beauty of your photos.
- Reading a curve
- Creating a Curves adjustment
- Working with the Adjustments panel
- Using presets and eyedroppers
- Adding and adjusting anchor points
- Using the Luminosity blend mode
- Curves for color
- Creativity with Curves