What do curves do in photoshop

Contrast defines the relationship between the tones in your photo. A high contrast image will generally have strong shadows and highlights, with a lot of saturation.

Low contrast photos will look flat and almost gray. A lot of photos can benefit from an increase in contrast. So how can you do this? First of all, click on the line about a quarter of the way in from the left. This will darken your entire image. After this, you should create a second point, this time about three-quarters of the way along and drag it up a little. Again, only a small amount is needed for this to work. This S-Curve is probably one of the most common ways for you to create contrast with Curves.

Notice how the line now resembles the shape of the letter S. As another way of working, start by placing a point in the center. This will be your anchor point. Now create the point for your shadows and drag it down. By clicking and dragging the center up, you both brighten the image and increase contrast. If you want to control the image more, just add more points.

You can also move the endpoints of the line in. This adjustment makes a huge difference with this image, where most of the tonal information is in the center of the histogram. Notice that as you move the endpoints in the black and white points on the Input Slider move to a corresponding position — so you could also just move these sliders. Note how these change the histogram and most importantly, also notice how these changes influence the image: reflection detail on the side and underside of the boat become clearer for the inverted S-curve while water texture becomes more washed out and the opposite for the S-curve.

Why redistribute contrast if this is always a trade-off? Since actual scenes contain a greater lightness range dynamic range than we can reproduce on paper, one always has to compress the tonal range to reproduce it in a print.

Curves allows us to better utilize limited dynamic range. Midtone contrast is perceptually more important, so the shadows and highlights usually end up bearing the bulk of this tonal compression. Most films and photo papers therefore use something similar to an S-curve to maintain midtone contrast. Move your mouse over the image right to see how an S-curve can help maintain contrast in the midtones,and note its similarity to an actual film curve below.

Each film's unique character is primarily defined by its tonal curve. The camera therefore has to apply its own tonal curve to the RAW file format to maintain accuracy. In summary: tonal curves are required for every image in one form or another — whether this be by our eyes, the film emulsion, digital camera, display device or in post-processing. The key concept with curves is that you can never add contrast in one tonal region without also decreasing it in another.

In other words, the curves tool only redistributes contrast. All photographs therefore have a "contrast budget" and you must decide how to spend it — whether this be by spreading contrast evenly straight diagonal line or by unequal allocation varying slope.

Furthermore, curves always preserves the tonal hierarchy unless uncommon curves with negative slope are used. This means that if a certain tone was brighter than another before the conversion, it will still be brighter afterwards — just not necessarily by the same amount. Three anchor points shown above each for shadows, midtones and highlights are generally all that is needed in addition to the black and white points. A tricky aspect is that even minor movement in an anchor point can result in major changes in the final image.

Abrupt changes in slope can easily induce posterization by stretching tones in regions with gradual tonal variation. Therefore moderate adjustments which produce smooth curves usually work best. If you need extra fine-tuning ability, try enlarging the size of the curves window. Pay close attention to the image histogram when making adjustments. If you want to increase contrast in a certain tonal peak, use the histogram to ensure that the region of greater slope falls on top of this peak. The exception to the contrast trade-off is when you have unused tonal range, either at histogram edges or as gaps in between tonal peaks.

If these gaps are at the histogram's edges, this unused tonal range can be utilized with the black and white anchor points as with levels tool.

If the gaps occur in between tonal peaks, then a unique ability with curves is that it can decrease contrast in these unused tones — thereby freeing up contrast to be spent on tones which are actually present in the image. Moving a point either up or to the left maps a lower Input value to a higher Output value, and the image lightens. Optional To adjust the color balance, in the Properties panel, choose the channel you want to adjust from the menu to the left of the Auto button.

Dragging a control point left or right increases or decreases the contrast. You can add up to 14 control points to the curve. To remove a control point, drag it off the graph. As you adjust the tonality, the graph continues displaying the original diagonal baseline and image histogram as references. These options can be turned off, see Set Curves Display Options. Points on the curve remain anchored until you move them. You can make an adjustment in one tonal area without affecting other areas.

Light Displays the intensity values for RGB images in a range from 0 to , with black 0 at the lower-left corner. Show Channel Overlays Displays color channel curves superimposed on the composite curve.

Histogram Displays a histogram of the original image tonal values behind the graph. Baseline Displays the original image color and tonality as a degree angle line for reference, Intersection Line Displays horizontal and vertical lines to help you align control points as your drag them relative to the histogram or grid.

Auto applies an automatic color correction using the current default setting. To change the default setting, choose Auto Options from the Properties panel menu and set the options in the Auto Color Correction Options dialog box. For more information on these options, see Set Auto adjustment options. When applying a Curves adjustment, use the black and white sliders to quickly set the black and white points pure black and pure white values in the image.

Drag the black and white point sliders to any point along the horizontal axis. Note that the Input value changes as your drag. If the image uses the full tonal range, but needs midtone contrast, Click the Curves icon in the Adjustments panel. Drag the curve into an S shape.

Legal Notices Online Privacy Policy. Buy now. Curves adjustment Search. Make it. Curves overview. Adjust image color and tone with Curves. To apply a Curves adjustment, do one of the following:. Click the Curves icon in the Adjustments panel.