Use Opacity to specify a multiplier to apply to the image's starting opacity.

Values below 1.0 increase transparency; 0.0 is invisible. For images that have some transparency, values above 1.0 increase the opacity of the transparent portions.

If you add transparency to an image with the Opacity transformation, Image and Video Manager creates derivative images in formats that support alpha-channel transparency. With alpha-channel transparency, images can have gradient levels of transparency, not just the binary options of fully transparent or fully opaque. If you do not want transparency in the derivative images, you can apply the Background Color transformation after Opacity. Because Image and Video Manager applies transformations starting at the top of the list, this ensures that the background color fills in the transparency that Opacity created.

If you add the IMQuery transformation to a policy, use the im variable, and select Opacity, you can use a query string to adjust the opacity of any image using this policy. See Syntax and Examples for the syntax for the query string parameter.