27) After you have converted the image, you can now adjust the Levels. In order to leave the color information unaltered, you should modify the Levels only on the “L” channel as shown in figure 26.

28) There's another way and a better one in the same time. It is called Blending Modes. You will notice that at the top left of the Layers palette there is a drop down list which is labeled "Normal" as shown in figure 27 . Use this control to change the Blending Mode for each layer in an image. Blending Modes determine how each layer is combined (blended) with the one underneath it. Look at the very bottom of the list where you will find "Luminosity". If we change the Blending Mode on an Adjustment Layer to Luminosity, the choices in it will only affect how bright the layer underneath it is, leaving its hue and saturation unchanged.

29) After you have made all the desired modifications to the image and the result, contrast and brightness-wise, is satisfactory, all you have to do is save the final image under the desired name, location and file type (File > Save as).

30) In the end here are some tips for using with the Levels settings. Minimize use of the levels tool, because if you stretch the image histogram, you increases the possibility that posterization will occur (posterization occurs when the bit depth of an image decreases so much that it has a visual impact on the image). { see figure 28 and figure 29 }

Performing adjustment to levels on an individual color histogram or channel can adversely affect the color balance, so color channel levels should only be performed when necessary or intentional color shifts are desired.