Picture Transfer Protocol

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Picture Transfer Protocol (PTP) is a widely supported protocol developed by the International Imaging Industry Association to allow the transfer of images from digital cameras to computers and other peripheral devices without the need of additional device drivers. The protocol has been standardised as ISO 15740.

It is further standardized for USB by the USB Implementers Forum as the still image capture device class. USB is the default network transport media for PTP devices. USB PTP is a common alternative to USB MSC, as a digital camera connection protocol. Some cameras support both modes.

PTP specifies a way of creating, transferring and manipulating objects which are typically photographic images such as a JPEG file. While it is common to think of the objects that PTP handle as files, they are abstract entities identified solely by a 32-bit object ID. These objects can however have parents and siblings so that a file system-like view of device contents can be created.

A number of protocols have been developed that extend PTP. PTP/IP, developed by FotoNation and first implemented by Nikon, allows data transfer over a wireless network. Media Transfer Protocol, developed by Microsoft, allows for transfer over wireless or wired networks based in part on FotoNation's PTP/IP, but also allows users to transfer other media aside from pictures, as well as for tagging objects with extended metadata (such as title, artist and similar).

Both Microsoft and Apple include PTP support in their operating systems, from Windows Me onwards (excluding Windows CE), and Mac OS X v10.1 onwards, respectively. Microsoft implements PTP on Windows through Windows Image Acquisition.^[1]^[2] PTP on Linux and other free software/open source operating systems is supported by a number of libraries, such as libgphoto and libptp, libraries used by applications such as digikam and f-spot.