This tool is used to remove parts of the active layer or selection. It can be useful when working with multi-layered images as portions of an upper layer erased will allow lower layers to show through.
The Eraser works by marking areas of the layer as being transparent (i.e. having an Alpha value of zero) or partially transparent (Alpha < 255).
Areas completely erased will have the original RGB color information replaced with white (hexadecimal code #FFFFFF).
Areas undergoing partial erasure will retain the original color information and have a lower opacity value applied.
Erasing may result in a checkerboard pattern being shown. This pattern is used to denote areas of the image that are transparent - the pattern is not actually part of the image and will not be seen outside of paint.net's editing environment.
Example - Eraser Tool
Original ImageAfter using the Eraser Tool in the middle of the image. Note the gray and white checkerboard pattern (denoting transparency).
The Eraser inherits the Brush Width and Hardness settings from the Tool Bar.
The Brush Width determines how wide the circular tip of the Eraser will be. Note that the tip of the Eraser will always be circular - it is not
possible to alter this.
Example - Brush Width
Eraser Tool showing three brush widths.
At the top the Brush Width is set to five pixels wide.
In the middle the Brush Width is 20 pixels.
At the bottom the Brush Width is 65 pixels.
Hardness indicates how hard or soft the erased edges are.
A low setting gives a softer or more diffuse edge, while a high setting gives a harder or more well defined edge.
Example - Hardness
Eraser Tool showing three hardness settings.
At the top the Hardness is set to 10%. Note the soft edge.
In the middle the Hardness is to 50%.
At the bottom the Hardness is 100%.
Hardness can be considered the strength of the anti-aliasing used to soften edges.
Because of this link, the Hardness setting is ignored if Anti-Aliasing is disabled.
The Eraser inherits the Alpha value of the Primary color if the Left Mouse button is used.
It inherits the Alpha value of the Secondary color if the Right Mouse button is used. This makes it possible to make the 'soft' erasings.
Example - Alpha Setting
Eraser Tool showing three Alpha settings.
On the left, the Alpha Setting is set to 60. The opacity of the erased area will be 255-60=195 and the original color information will be retained.
In the middle the Alpha Setting is set to 120. The opacity of the erased area will be 255-120=135. Again, the original color information will be retained.
On the right, he Alpha Setting is set to 255 (maximum). The opacity of the erased area will be 255-255=0. The original color information will be replaced with white (#FFFFFF)
The Eraser tool in Microsoft Paint works by painting with white. If this behavior is desired, use the Paintbrush tool and select white as Primary color in the Colors Window.