Spot the Difference The image on the left has poor contrast, and it misses real blacks and pure whites.
Brightness / Contrast This is the most basic tool, and the most intuitive to use for the less experienced ones. The two sliders basically do what its written on the tin.
Histogram Digital SLR cameras optionally display the histogram of the pictures taken.
Histogram In statistics, a histogram is a graphical representation showing a visual impression of the distribution of data. It is an estimate of the probability distribution of a continuous variable
Histogram An image histogram is a type of histogram that acts as a graphical representation of the tonal distribution in a digital image. It plots the number of pixels for each tonal value The horizontal axis of the graph represents the tonal variations, while the vertical axis represents the number of pixels in that particular tone
Levels Tool The Levels tool can be used to adjust the white and black point It also provides a slider to set the mid- tone point.
Curves Tool Curves provides enhanced control over the distribution of contrast and brightness. Control Points can be placed to make sections of the curve slope steeper (increase contrast) or less steep (decrease contrast).