Custom images can be created and assigned to a command to identify it when it is placed on a user interface element.
Button images can be created with the Button Editor in the Customize User Interface (CUI) Editor or an external image editing software. The images you create should be in one of two sizes: 16x16 and 32x32 pixels. Once an image is created, it can be assigned to the Small Image and Large Image properties of a command. After an image is assigned to a command, it is imported into the working customization (CUIx) file to make it easier to share customization.
When a command is added to a ribbon panel, toolbar, or pull-down menu, the assigned image is displayed on the ribbon panel or toolbar button, or the image is displayed to the left of the menu item.
If your images are defined with sizes other than 16x16 or 32x32 pixels and assigned to a command that is used on a ribbon panel, set the RIBBONICONRESIZE system variable to 0. The program does not resize ribbon button images to a standard size when RIBBONICONRESIZE is set to 0. You must also set the Button Style property for the command or drop-down menu to LargeWithoutText.