Hey guys, one of our members has asked for a tutorial on Curves, I have chosen to do the tutorial in two parts, so here is the first.
Photoshop Curves is similar to Levels, they both take the image tones and allow you to stretch or compress them, brightening or darkening an image. The big difference between the two is that Levels is limited to black, white and midpoint control, and Curves is able to adjust tones using upto 16 anchor points. Curves offers more flexibility over levels, it offers control over the parts of an image that you want to adjust.
So, to open up the Curves dialog you can either click, Image > Adjustments > Curves (Ctrl/Cmd+M) to directly change the image, or choose to add an adjustment layer (which can be tweaked and changed or deleted, during processing) Layer > New Adjustment Layer > Curves.
Below is an image of the Curves ‘grid’, this is a basic way at seeing how curves works. In addition to this notice the axis gradients, the one that runs horizontally depicts the original tonal range of the image and the vertical axis depicts any changes you make.
By clicking and dragging any part of the line you will make an adjustment to the tones of the image. To show examples of this, I have taken the image used in our HDR experiment.
So by dragging the line to curve to the left, you will produce a lighter image…..
…..and by dragging the line to curve to the right, you will produce a darker image.
To increase the contrast of your image (making light parts lighter and dark parts darker) you can drag the line to form an ‘S’ shape.
You will find a drop down menu, with the word ‘default’ currently displayed, by clicking on this you will find a number of preset curve adjustments, each producing a different outcome, take some time to experiment with these, you will produce some interesting results.
There are however a couple of things that should be avoided unless they are used to produce an intended result.
By adjusting the line to the below image, you will produce a ‘flat spot’ which kills the contrast of an image and anything on that line becomes grey…..
….. and by creating a ‘down spot’ in the line you will turn that part of the image into a negative version.
So now the basics of Curves has been covered, I have included below an example of how to use this in the processing of the image previously used above.
1. Open image in Photoshop (I use CS5). Add new adjustment layer – Layer > New Adjustment Layer > Curves. Adjust default setting to Darker (RGB).
2. Add new adjustment layer – Layer > New Adjustment Layer > Curves. Adjust default setting to Increase Contrast (RGB).
3. Add new adjustment layer – Layer > New Adjustment Layer > Hue/Saturation. Adjust Saturation to -50. I choose to do this, as increased contrast comes with increased saturation.
The end result takes you from this…..
…..in three easy steps. Whilst this technique is simple, it is also effective for processing images for a darker feel.
You can view part two of this tutorial here.
Hope you guys find this helpful… if you have any questions please ask away
If you have a tutorial you would like to see, then please let us know here.