Brightness refers to amount of light, 100% is maximum light and 0% is minimum light or no light - black.
Levels in Photoshop are color and brightness correction.
color correction,brightness-contrast correction,converting to black-white...
Photoshop can be used to crop pictures, remove or replace unwanted objects, adust the brightness/exposure, saturation, and hue, or to add artistic effects to a photo.
in photoshop you change it via adjustments panel. just go to the window tab and click on adjustments and then the sun icon. from here you can change the brightness and contrasts.
The features that come with the Photoshop CS3 are it's accuracy, it's new interface design, it's performance, the new curves, the new brightness and contrast, and/or it's black and white adjustments.
You can adjust if they are applied to Shadows, Midtones, Highlights, or the Saturation, you can adjust the strenth of each variation, you can adjust the hue of the variation, or you can adjust the brightness by using variations.
In Photoshop U can use Curves from Adjustments palette or Brightness/Contrast and in Camera Raw all adjustments are non-destructive.
You can turn color pictures into black and white. You can adjust the sharpness and brightness. You can also make pictures bigger or smaller.
To adjust the brightness levels of the overal picture, or individual R,G,and B values by either boosting or limiting the light and dark values, or adjusting the bias of the gamma.
you can do this under Image> Adjustments> Brightness/Contrast and pull the slider on the Brightness down. You may want to increase the contrast if needed. Duplicate the Background layer, then set the Blending Mode of that layer to Multiply. From there you can add a Layer Mask and paint away any areas that got too dark.
Easiest and non-destructive (means you can change settings at any time after applying them even after saving and reopening image) way is to use Brightness/Contrast adjustments from Adjustments panel (Window > Adjustments) or go to Layer > New Adjustments Layer > Brightness/Contrast.
Photoshop Elements is Photoshop but with less features, so Photoshop is better but it is professional level software. For home use or to get started Photoshop Elements is OK.