Methods disclosed permit compositing operations to be performed on images using an associated mask even in situations where the image and the mask differ in size. In some embodiments, image and mask data may be specified as a soft mask image in a page description language such as PDF. Scaling operations may be performed on the image, mask, or on both the image and mask when they differ in size. Compositing operations may be performed on the scaled image and/or mask after they have been scaled to the same size. Composting operations in situations where the original mask and image are of the same size are not affected by scaling operations.