Image upload limit

[Luashine]

I uploaded this totally cool new thing Notepad++ Jass/vJass syntax highlighter and wanted to attach a big beautiful web image that showed syntax highlighting of a big boring code file with vJass.
The screenshot was 8-bit palette PNG, why would you need to know? Because I optimized it very well to be small in size But the website didn't let me upload it and responded with an error.

Format           : PNG
Format/Info      : Portable Network Graphic
File size        : 642 KiB

Image
Format           : PNG
Format/Info      : Portable Network Graphic
Compression      : Deflate
Width            : 1 021 pixels
Height           : 19 804 pixels
Color space      : RGB
Bit depth        : 8 bits
Compression mode : Lossless
Stream size      : 642 KiB (100%)

I think the size/resolution also called bits per pixel is reasonable and should've been allowed.