Add PATENTS file
diff --git a/PATENTS b/PATENTS
new file mode 100644
index 0000000..5a1eaf0
--- /dev/null
+++ b/PATENTS
@@ -0,0 +1,73 @@
+Digital Negative (DNG) Specification patent license
+
+Adobe is the publisher of the Digital Negative (DNG) Specification
+describing an image file format for storing camera raw information
+used in a wide range of hardware and software. Adobe provides the DNG
+Specification to the public for the purpose of encouraging
+implementation of this file format in a compliant manner. This
+document is a patent license granted by Adobe to individuals and
+organizations that desire to develop, market, and/or distribute
+hardware and software that reads and/or writes image files compliant
+with the DNG Specification.
+
+Grant of rights
+
+Subject to the terms below and solely to permit the reading and
+writing of image files that comply with the DNG Specification, Adobe
+hereby grants all individuals and organizations the worldwide,
+royalty-free, nontransferable, nonexclusive right under all Essential
+Claims to make, have made, use, sell, import, and distribute Compliant
+Implementations.
+
+“Compliant Implementation” means a portion of a software or hardware
+product that reads or writes computer files compliant with the DNG
+Specification.
+
+“DNG Specification” means any version of the Adobe DNG Specification
+made publicly available by Adobe (for example, version 1.0.0.0 dated
+September 2004).
+
+“Essential Claim” means a claim of a patent, whenever and wherever
+issued, that Adobe has the right to license without payment of royalty
+or other fee that is unavoidably infringed by implementation of the
+DNG Specification. A claim is unavoidably infringed by the DNG
+Specification only when it is not possible to avoid infringing when
+conforming with such specification because there is no technically
+possible noninfringing alternative for achieving such conformity.
+Essential Claim does not include a claim that is infringed by
+implementation of (a) enabling technology that may be necessary to
+make or use any product or portion thereof that complies with the DNG
+Specification but is not itself expressly set forth in the DNG
+Specification (for example, compiler technology and basic operating
+system technology), (b) technology developed elsewhere and merely
+incorporated by reference in the DNG Specification, or (c) the
+implementation of file formats other than DNG.
+
+Revocation
+
+Adobe may revoke the rights granted above to any individual or
+organizational licensee in the event that such licensee or its
+affiliates brings any patent action against Adobe or its affiliates
+related to the reading or writing of files that comply with the DNG
+Specification.
+
+Any Compliant Implementation distributed under this license must
+include the following notice displayed in a prominent manner within
+its source code and documentation: "This product includes DNG
+technology under license by Adobe Systems Incorporated.”
+
+No warranty
+
+The rights granted herein are provided on an as-is basis without
+warranty of any kind, including warranty of title or noninfringement.
+Nothing in this license shall be construed as (a) requiring the
+maintenance of any patent, (b) a warranty or representation as to the
+validity or scope of any patent, (c) a warranty or representation that
+any product or service will be free from infringement of any patent,
+(d) an agreement to bring or prosecute actions against any infringers
+of any patent, or (e) conferring any right or license under any patent
+claim other than Essential Claims.
+
+Reservation of rights
+
+All rights not expressly granted herein are reserved.
