Light adjustment
A color image is having two parts-
One is known as a gray scale tone and the second part contains the information because of these information we can see a colored image. 'TONE' is stands for Grey scale information.
If a photo is too dark or is too bright than it means that the tonal area of that photo is disturbed.
To fix this problem photoshop has added few tools......
LEVEL
Level tool is very easy to use and also the best one to adjust the tone of photo.
Go to Image -- adjustment -- Level
Level dialog box will open,
There are three sliders in the dialog box
First is shadow slider and second is midtone slider and third one is highlight slider
If we will adjust the shadow slider towards right than image will be dark.
If we will adjust the midtone slider towards right than image will be dark & midtone will decrease.
If we will adjust the midtone slider towards left than image will be light.
If we will adjust the highlight slider towards left than image will be light.
Midtone slider is ideal for increase tone of an image.
AUTO LEVEL
Auto level is available in IMAGE -- ADJUSTMENT -- AUTO LEVEL
It can adjust the tone of the image automatically but its accuracy rate is poor, so i will suggest that adjust the tone manually instead of using auto level.
AUTO CONTRAST
Auto contrast is available in IMAGE -- ADJUSTMENT -- AUTO CONTRAST
Auto contrast is also similar to auto level.