1. A method, comprising: receiving an electronic document implementing a personalized product design receiving by one or more processors a scene image comprising a placeholder element: receiving a scene description, the scene description comprising computer-readable scene rendering instructions implementing warping and composing functionality to specify how an injectable scene element is to be warped and composited with a scene to dynamically generate a composite image processing the received scene description using the received scene image as the scene image in the scene description, and further using the electronic document as the received injectable scene element, the processing comprising performing the warping and compositing functionality specifying how the injectable scene element is to be warped and composited with the received scene image to dynamically generate a personalized composite scene image; embedding the personalized composite scene image into a browser-renderable document: wherein the scene description comprises a warping specification which defines one or more geometric transformations that change the geometry of an image, and a compositing specification which defines how to composite the specified scene images and the received injectable scene elements and specifies application of one or more of the defined geometric transformations to one or more of the specified scene images and received injectable scene elements, and wherein the compositing specification specifies a composition tree comprising a plurality of individual composite descriptions, the method further comprising: processing each of the plurality of individual composite descriptions to generate a respective individual flattened composite image prior to processing a different composite description which includes the respective individual composite description and such that the respective individual flattened composite image is utilized in place of the respective individual composite description in processing the different composite description.