Playback
========
LEFT and RIGHT arrows play the video in that direction at the configured FPS.
Hold SHIFT + direction to play at 10x speed.
Hold CTRL + direction to step through one frame at a time.
(Alternatively, COMMA and PERIOD can be used to step left and right respectively)

Contrast
========
Contrast is controlled by rescaling the pixel intensities between a min and max threshold.
Hold UP/DOWN to change the lower threshold (increasing it blacks out dim pixels).
Hold SHIFT + UP/DOWN to change the upper threshold (decreasing it whites out bright pixels).

Events
======
LETTER keys mark the start of an event associated with that letter.
SHIFT + LETTER marks the end of the event.
Events of different types can overlap.
Delete an event initiation by terminating it at the same frame, and vice versa.

Status
======
SPACE shows in-progress events.
RETURN shows the current result table in the console.
BACKSPACE shows the current frame number and contrast thresholds in the interval [0, 1].

Prompts
=======
DELETE shows a prompt asking which in-progress event to delete.
CTRL + n shows a prompt asking which in-progress event to add a note to, and the note.

In order to interact with a prompt, you will need to click on the console and enter your response.
Then, click on the fran window to keep annotating.

Other
=====
CTRL + s to save
CTRL + z to undo
CTRL + r to redo
CTRL + h to show this message
