Grayscale, hard-edged pattern
Indexed-palette flat-fill logo
tRNS chroma-key transparency (PDF color-key /Mask)
Each opaque PNG below embeds via byte-for-byte /FlateDecode pass-through - the PNG's own compressed pixel data, unchanged - instead of being decoded and re-encoded as a lossy JPEG. Every edge stays exactly as sharp as the source, and the embedded file is typically smaller too.