Standard
Portable Network Graphics: a lossless raster image format supporting palette (PNG-8) or full-color modes with alpha transparency, widely used on the web.
PNG-8 at 124 colors encoded a red-text test poster in 48,481 bytes at an edge error of 0.13 Delta E, smaller and cleaner than every JPEG export. For flat graphics like this one, an export tool that converts everything to JPEG ships bigger files with dirtier red text.
Reality
Oizom replaced an hourly Python heatmap job with an on-demand Go service that renders 20 air-quality images in 30 ms. Per-function timing then traced 80% of each render to PNG encoding, on test images small enough to keep the interpolation cheap.
Reality
Headless Chrome 149 wrote the same 1,345,909-byte PNG via canvas.toBlob at quality 0.1 and at 1.0, one developer's measurements show. A PNG export slider only changes the file if the tool downscales, quantises colours or switches to WebP or AVIF.
Reality
Browsers decode eight image formats and encode three. A dev.to post documents what happens when you ask the canvas API for one of the other five: the success callback fires, and the blob it carries is a PNG.
Reality
Real headers and an exact byte count pull against each other, and every format loses the fight differently. One generator author walked 25 of them and catalogued the bugs that browsers forgive and CI parsers refuse.
Reality
The HTML spec mandates the silent substitution, blob.type is the only record that it happened, and a user-agent lookup table cannot stand in for the check.
Reality
One developer's APNG test set inflated by up to 2.41x when adaptive per-scanline filtering was switched on. The spec's rule scores byte magnitude; DEFLATE charges for repetition.
Reality
A browser image tool's writeup on binary-searching JPEG quality, and on PNG, where the quality-shaped proxy it searches cannot address 155 of the 255 available palette sizes.
Reality