PhotoPad allows for photos to be edited non-destructively, meaning that a series of modifications can be applied without losing any image data.
For example, if darkening an image, parts of the image may become completely black. After this modification is applied, brightening the image would turn these black areas into a shade of gray, and the detail of the image would be lost. With PhotoPad's non-destructive editing, the parameters of any modification can be changed at any time after the modification is applied. So in this example, instead of attempting to brighten a darkened image, the amount of darkening performed originally can be adjusted.
Each modification made in a PhotoPad project is represented with an Effect layer. To take advantage of non-destructive editing, it is best to only create one of each effect layer needed. When making adjustments to an image, reuse the effect layers you have already created rather than creating new ones.