Opinion of 8-bit PNG for Orthophotos

I generated a tilemap from a large orthophoto using gdal2tile. Looking at a file of 256x256 at dense areas, file sizes above 150kb.

This adds up a bit when loading many tiles when i compared to bingmaps etc (below 100kb) .

Tested a few tiles, i converted it to PNG 8-bit format using paint.net

Visually it looks the same but the file sizes are 1/3 of the original.

My question are

  1. Is it accepted to use 8-bit PNG. The original file is a colored orthophoto of a city.

  2. Reading up on transparency, it seems 8-bit supports it. It is needed in my application.

TIA

Cesium supports any PNG image. Second part is out of the scope of Cesium, but transparency is only preserved in 32-bit when I save out a file in paint.net.

Thanks,

Gabby