Brightness and Contrast
The Brightness/Contrast adjustment lets you make simple adjustments to the tonal range of an image. Moving the brightness slider to the right increases tonal values and expands image highlights, to the left decreases values and expands shadows. The contrast slider expands or shrinks the overall range of tonal values in the image.
The Levels Adjustment
Levels is a tool in Photoshop which can move and stretch the brightness levels of an image histogram. You can adjust brightness, contrast, and tonal range by specifying the location of complete black, complete white, and mid tones in a histogram. Since every photo’s histogram is unique, there is no single way to adjust the levels for all your photos. A proper understanding of how to adjust the levels of an image histogram will help you better represent tones in the final image.
Hue and Saturation
Hue/Saturation lets you adjust the hue, saturation, and lightness of a specific range of colors in an image or simultaneously adjust all the colors in an image
The Photoshop Curves command is your most powerful tool for adjusting tones to brighten, darken, add contrast and shift colours in your image.
Fill Adjustment Layer
Fill layers let you fill a layer with a solid color, a gradient, or a pattern. Unlike adjustment layers, fill layers do not affect the layers underneath them.
Black and White Adjustment Layer
The Black & White adjustment lets you convert a color image to grayscale while maintaining full control over how individual colors are converted. You can also tint the grayscale by applying a color tone to the image, for example to create a sepia effect.
The Curves Hidden Auto Features
In this video you will learn how to add contrast and colour correct using Curves and the hidden features under the Auto button.