Image caching

The technology was first implemented in 1995 by Avid Technology in the Ikegami Camcutter professional digital video camera of the “Editing” series "Under the trade name eng. Retro Loop (literally - reverse loop ) ^[1] . Due to the use of a hard disk instead of a VCR with instant access to any place in the video, the camera allowed recording a “loopback” of video in standby mode. At the same time, the beginning of the video recording, which was outdated by 1 minute, was replaced with fresh material, and after the expected event, all content saved for this time interval was transferred by the button to the recorded status. Thus, the finished video does not start from the moment you press the button, but a minute before. To record an event that is unpredictable in time, it is sufficient to enable this mode, which can record a video loop for an unlimited interval ^[2] .

In modern digital video cameras, this same function is more often called “image caching” or “recording in cache memory” ( English Picture Cache Recording ) ^[3] . For example, the professional Sony HDW-650 camcorder thus saves up to 8 seconds of audio and video data that have fallen into the buffer memory before pressing the record button ^{[4] [5]} . Another model “Sony PMW-320” saves 15 seconds preceding the start of the recorder ^[6] . In Panasonic cameras, the mode received the trade name “pre-recording” ( Pre-Rec or Pre Record ), and in JVC equipment this function is called “retro-cache” ( English Retro-Cache ) ^{[7] [8]} .

A similar method of taking snapshots of events that occurred before pressing the shutter button is implemented in expensive camera phones using the Pro Capture mobile application. Shooting is carried out continuously with high frequency with the trigger button being half-pressed. In this case, the pictures are stored in the buffer for a specified interval, after which their place is occupied by more recent ones. After pressing the shutter button completely, all recorded images can be saved to a memory card , including those taken before pressing the button. In 2016, this feature was added to the mirrorless Olympus OM-D E-M1 Mark II ^[9] . Due to continuous shooting with a high frequency of up to 60 frames per second, caching allows you to find snapshots of fast processes that cannot be captured directly by pressing a button. This possibility compensates for the shortcomings of human reaction, and is relevant when shooting sports or wildlife.

• Bullet time

• Mikhail Kashin. Pandemonium in Las Vegas // 625: scientific and technical journal. - M .: Publisher 625, LLC, 1995. No. 3 . - ISSN 0869-7914 .