Adobe released a quick summary on their blog of their new DNG (Digital Negative) 1.4 specifications. Here is a quick summary:
Default User Crop:the new tags allows the crop setting to be respected but to also allow the customer to “un-crop” the image to see the entire sensor area.
Transparency: when images are “stitched together” in an alignment process or panorama process the resulting image could have “undefined” pixels around the edges. The new specification update now allows for those undefined areas to exist in a raw file format.
Floating Point (HDR):HDR images have a high dynamic range that will not fit into a 16-bit linear integer encoding. Floating point storage of information allows for a larger amount of dynamic range to be stored within a file.
Lossy Compression:a lossy compressed DNG file is much smaller but maintains the flexibility of raw data.
DNG Proxies:combine the ability to utilize lossy compression with downsampling.