WebP2 triangle preview

We use triangulation + colormap to compress images into a very small preview. See the paper presented at ICIP 2018.
The compressed data is the base64 input of the text-area below. The decoder is ~400 lines of javascript + WebGL.

The libwebp2 repository is located at https://chromium.googlesource.com/codecs/libwebp2.
You can generate preview base64-strings using for instance: extras/mk_preview input.png -b64.
The mk_preview research tool contains a lot of optimizing options to play with.

Some pre-calculated examples:

250 bytes	Decoded result

[ grid = 64 x 96, nb_colors = 5 nb_pts = 218]
Colormap (w/ use counts): (76) (72) (31) (34) (9)
show triangles noise amplitude decoded image width
Text version of the compressed data: 64 96 5 0 4 32 30 1 14 40 32 1 26 42 34 1 36 50 34 1 44 58 34 1 c..............................................................c .........c...................................................... ........................................................c....... ..................................c............................. c..............................................c................ .......................c........................................ ................................................................ ..................................c............................. .........................c...................................... .............................................c.................. ...............................a.........d.....................c ..........................b...........a......................... ................................................................ ................................................................ .......................b.d...e.................................. c....d...............d...................a.d......d............. ....................d.................a......................... ..........................................................d..... .c......d............b.........d..........a...c................. ......................b..e.................b...................c ......c...c.....d...........d.......b..............c..d......c.. ..................d.b.a..b...b...b.............................. .b..............c.....................a...............d.d....... ........................e......d...d......a........b............ ...........................d..d.....b........................c.. ............b.........a............................c............ ....b...................d.......d..............b......c......... .....................................a.............b............ .............................b.....b..................b......... ...............................................................a a..............................................b................ ...............................c.....................a.......... ........................a..d...............a.................... .............b......................a.a......................... ...........a...............a...a................................ .........b........b.................b........................... ..................................b.......................b..... ..............b.........a....................a..b.....b......... ..................b......a..............a............b....b..... ................a..a....................................c....... ...............................d.......b.......a................ ........b..................d........d....................b.....a .......b................................b............c.......... ....................a..................b........................ ......................b.d.e................a.................... .......................................b..........a.....c..c...b ..............b....a............................b............... ................a..................e........c...........a...b... ......................e..........................a.............. .......................................b....a................... ...........b.........b.......e...e......................a....... ..b.....................................a....................... ............a..............b....................a........a...... .....b............................b............................. ....................................a....................b...... a........b.....a................................................ ..............................................b.........a....... ...........a.....a.............................................a 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........b........d..d....d...a.................................. ................................................................ .......a......a........d...d............a.......a............... ..................................b........b.................... ..................b.....................b....................... .............a.................................................. ..................c................b............................ ................................................................ ....................d.b......................................... ...............................b...............a................ ............a.b.............b....b...a.......................... .........................................a...................... a...................b....a..........aa.........................a a............................................................... ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ a..............................................................a

WebP2 triangle preview

Colormap (w/ use counts):(76) (72) (31) (34) (9)

Colormap (w/ use counts):
(76)
(72)
(31)
(34)
(9)