Comment by perihelions
Comment by perihelions 2 days ago
I think the .png images on this website are larger than the uncompressed originals (1-bit depth, 1 bit per pixel).
Comment by perihelions 2 days ago
I think the .png images on this website are larger than the uncompressed originals (1-bit depth, 1 bit per pixel).
I know; I mean to say they're larger file sizes—the PNG compression ratio is effectively less than one.
Take the first one, "acius.png", at 84,326 bytes. If you losslessly scale back to the original size (1/4th) and convert to 1-bit NetPBM, it's 51,851 bytes, without compression. I thought that was remarkable.
The PNG files seem to be very poorly compressed.
$ oxipng -o max --strip all -avZ --fast acius.png
Processing: acius.png
2304x2880 pixels, PNG format
8-bit Indexed (2 colors), non-interlaced
IDAT size = 84251 bytes
File size = 84326 bytes
Transformed image to 1-bit Indexed (2 colors), non-interlaced
Trying filter None with zopfli, zi = 15
Found better result:
zopfli, zi = 15, f = None
IDAT size = 24466 bytes (59785 bytes decrease)
file size = 24541 bytes (59785 bytes = 70.90% decrease)
24541 bytes (70.90% smaller): acius.png
Yep, I upscaled them by 400% so they’re easier to view on modern displays.