Understanding+Levels

 The Levels Tool

When it comes to editing images in Photoshop the first thing we always want to do is fix any overall tonal and/or color problems in the image (commonly referred to as "global" problems) before moving on to more specific problem areas ("local" problems), and the tool of choice for the task is the same today as it's been for years - Photoshop's **Levels** command, which not only handles the job like a pro, it makes overall tonal and color correction incredibly simple and easy.



Here are some sample Levels Histograms you might find: 

When considering adjusting the black and white point levels of your histogram, ask yourself: is there any region in the image which should be completely black or white, and does the image histogram show this? Most images look best when they utilize the full range dark to light which can be displayed on your screen or in a print. This means that it is often best to perform levels such that the histogram extends all the way from black (0) to white (255). Images which do not extend to fill the entire tonal range often look washed out and can lack impact. The image below was taken in direct sunlight and includes both bright clouds and dark stone shadows-- an example of where there should be at least some regions that are portrayed as nearly white or black. This histogram can be extended to fill the entire tonal range by adjusting the levels sliders.



On the other hand, be wary of developing a habit of simply pushing the black and white point sliders to the edges of the histogram-- without also paying attention to the content of your image. Images taken in fog, haze or very soft light often never have fully black or white regions. Adjusting levels for such images can ruin the mood and make your image less representative of the actual scene by making it appear as though the lighting is harsher than it actually was. One should also be cautious when moving the black and white point sliders to the edge of the histogram, as these can easily clip the shadows and highlights. A histogram may contain highlights or shadows that are shown with a height of just one pixel, and these are easily clipped. This is often the case with low-key images.

Adjusting Mid Tones Moving the midtones slider compresses or stretches the tones to the left or right of the slider, depending on which direction it is moved. Movement to the left stretches the histogram to the its right and compresses the histogram to its left (thereby brightening the image by stretching out the shadows and compressing the highlights), whereas movement to the right performs the opposite. Therefore, the midtone slider's main use is to brighten or darken the midtones within an image. When should you use the midtone slider? Consider the following: your image should contain full black and white, and even though the histogram extends to full black, it does not extend to white. If you move the white point slider so that it reaches the edge of the histogram, you end up making the image much brighter and overexposed. Using the midtone slider in conjunction with the white point slider can help you maintain the brightness in the rest of your image, while still stretching the highlights to white:



Some Samples for you to adjust