format has been criticized due to the limited amount of depth that can be displayed in an 8-bit greyscale. 2d-plus-Depth cannot handle transparency (semi-transparent objects in the scene) and occlusion (an object blocking the view of another). The 2d plus DOT format takes these factors into account. Additionally, it cannot handle reflection, refraction (beyond simple transparency) and other optical phenomena. Creation of accurate 2D-plus-Depth can be costly and difficult, though recent advances in range imaging have made this process more accessible. 2d-plus-Depth lacks the potential increase in resolution of using two complete images. Depth cannot be reliably estimated for a monocular video in most cases. Notable exceptions are camera motion scenes when object motion is static or almost absent, and landscape scenes when depth map can be approximated well enough with a gradient. This allows automatic depth estimation. In general case only semi-automatic approach is viable for 2D to 2D-plus-Depth conversion. Philips developed a 3D content creation software suite named BlueBox which includes semi-automated conversion of 2D content into 2D-plus-Depth format and automatic generation of 2D-plus-Depth from stereo. A similar semiautomatic approach to high quality 2D to 2D-plus-Depth conversion is implemented in YUVsoft's 2D to 3D Suite, available as a set of plugins for After Effects and NUKE video compositing software. Stereoscopic to 2D-plus-Depth conversion involves several algorithms including scene change detection, segmentation, motion estimation and image matching. Automatic stereo to 2D+Depth conversion is now possible due to new high performance software and GPU technology, even in live real-time mode. Alternatives Other 3D formats are stereo (left-right or alternating frames) and multiview 3D format (such as Multiview Video Coding and Scalable Video Coding), and 2D plus Delta. Notes References Graphics file formats Stereoscopy