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.
Custom images can contain a transparent color; the transparent color is often used as the background color of a custom image. By using a transparent color in a custom image, the custom image inherits the color of the user interface in which it is displayed.
Prior to AutoCAD 2017-based products, transparency in a custom image was handled by assigning the pixels of a
Starting with AutoCAD 2017-based products, the technique of using the color value 192,192,192 in BMP image files as a transparent color is no longer supported. All custom images that need to contain a transparent color must be saved as a PNG file. Existing custom images stored in BMP files must be converted to PNG files in order for the images to support transparency once again. After the existing custom images have been converted, the commands that are defined in a CUIx file and reference the original BMP files must be updated to reference the new PNG files.