To be implemented: 

1. Compression using zlib. In server side we wil compress with PHP as an example. On the Firmware will decompress with miniz.
2. BLE configuration. To make it portable, this will enable an easy configuration via an Android application, so it will just wait for Bluetooth if WiFi credentials are not set or cannot connect
3. Speed improvements

Point 1 is on the works and so far the most interesting at the moment since it will improve the download time about 8 times:

https://github.com/martinberlin/eink-calendar/issues/1

It could be rendering the image in 3 seconds instead of 12 which is a great speed improvement and also a battery lifespan increase.

Info about server side PHP compression: 

https://github.com/martinberlin/eink-calendar/blob/feature/compression/screenshot/compress.php#L105

It will use PHP native and fast: gzcompress with a high compression ratio. 

Serial output decompressing a 640 x 384 BMP / 1 Bit Depth: 

Done downloading compressed BMP. Length: 3078 
uncompress status: 0 length: 30866 millisDownload: 806 millis Decomp: 4 ms
BMP headers: Output File size: 30866
Width * Height: 640 x 384 / Bit Depth: 1