Editing Soft Shadows in a Digital Photograph

Abstract

This technique for modeling, editing, and rendering shadow edges in a photograph or a synthetic image lets users separate the shadow from the rest of the image and make arbitrary adjustments to its position, sharpness, and intensity.

Interactive Shadow Editing from Single Images

“…User-aided methods generally achieve more accurate and reliable shadow detection results at the practical cost of varying degrees of user input, such as quad map [5], shadow boundary [6,8], and sample of intensity [9,10,1]. As for the removal phase, some of them [2][3][4][5]7] adopt pixel-wise optimisation while others [11,6,[8][9][10]1] rely on the analysis of intensity profiles passing through shadow boundary.…”

“…The applications of this work only apply simple image manipulation to the original shadow matte and do not provide a manipulatable model for arbitrary shadow modification. A shadow editing system is first proposed in [11] which requires users to specify some boundary points of shadow. Their shadow edge model is manipulatable and supports controls for sharpness, darkness and shape of shadows.…”

“…Unlike previous work (e.g. [11]), our shadow editing model is fast, highly flexible and provides many more controls of shadow properties. The model is also universal and compatible with several shadow removal methods.…”

“…This shadow removal method gives a shadow-free image, a shadow mask, and many shadow scale attenuation profiles perpendicular to the shadow boundary. Some other shadow removal methods [11,6,[8][9][10] rely on intensity profile analysis are also compatible to our system. Synthesisation of shadow scale attenuation Shadow creation is simplified by synthesising intensity attenuation.…”

“…In previous work [11], users are required to specify multiple sparse control points defining shadow boundary. This user interaction requires multiple delicate mouse clicks to ensure accuracy of shadow modification.…”