Tonal Correction

i)Tonal corrections are those adjustments and changes you make to the brightness and contrast of your image. For years, Photoshop's workhorse tonal-correction tools have been the Levels control and the Curves dialog box, both of which can be applied either destructively or as adjustment layers.

The Levels control remains untouched in the Photoshop CS3 beta, but Adobe has made major changes to both the Curves and Brightness/Contrast tools.

ii) Tonal correction is use in image processing for Adjusts the contrast and color by identifying shadows, midtones, and highlights in the image, rather than in individual color channels. It neutralizes the midtones and sets the white and black points using a default set of values.