Levels and Curves 1

In general, 'levels' are the first thing addressed when you edit an image in Adobe Photoshop. Levels refer to defining the darkest and brightest areas of a photo. This image analysis requires the use of a histogram, which is the graphic illustration of the frequency distribution of the brightness values in a photo. It illustrates the allocation of different tonal values. If they aren't distributed throughout the total spectrum of black to white, you have to manually adjust them with the help of the levels.

To further improve the appearance of the photo, you can then use 'curves' for further modification.

In this video, Karsten Franke guides you through the process.