Zocoi Vietnamese /ʒoʊ kɔɪ/: (informal) Let's watch/read together

Imagemagick convert pdf to images with high quality

This is called supersampling technique. You set the density, say 4 times larger than nominal (72 dpi), thus -density 288 before reading the pdf. Then after reading it, you resize down by a factor of 4 or 25%
convert -density 288 image.pdf -resize 25% resultimage.png