Comment by Eric_WVGG | Hacker News Reader

Comment by Eric_WVGG | Hacker News Reader

This is a different thing, but it actually is possible for larger JPEGs to be faster (smaller file size) than smaller JPEGs.

Back when 4x "retina" resolution displays first hit the market, someone observed that you could take a 4x sized image, crank up the JPEG compression (from say 80% quality to 40%), and the resulting JPEG artifacts would visually disappear. The file size of larger, compressed images are frequently smaller than that of smaller, less-compressed images. And the render quality of "squishing" a 4x image down to 1x on a lower-resolution display similarly looks fine.

The images on the article in question are ironically broken, of course, but anyway I've been sampling images this way for years now. https://alidark.com/responsive-retina-image-mobile/

Lossy compression is fascinating because of how we can make certain optimizations based on the human eye, not keeping data in the right order necessarily. JPEG has seemed to stand the test of time so far, but new image formats like AVIF are definitely interesting.

In the inverse, smaller images can be bigger. There's a piece of software that I interact with a lot that's always trying to save space by crushing PNGs down to smaller dimensions, but in the process can introduce a lot of new complexity to the data (by turning what were crisp pixel edges into blurs), hurting PNG compression and increasing file size.

Yup, that makes sense.

Really I find the whole topic just infuriating… so much of the bullshit we've been dealing with since the nineties, from browser incompatibilities to javascript stagnancy to CSS layout (grid, flexbox) has gotten immeasurably better over the years. I never would have imagined that we'd still be stuck with JPG/PNG forever, though. (I hope that WebP is the savior but people still seem to be waffling on it.)

using the terms "small" and "big" referring to the weight of an image is confusing... it is better to use "light" or "heavy".

How do you measure the "weight" of an image? Sounds quite confusing to me.

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