BUTTERAUGLI(1)

💖 BUTTERAUGLI 💖

okay so bestie, butteraugli — measuring perceived differences between images. that's the whole vibe. let's get into it 🦋

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✨ NAME ✨

butteraugli — measuring perceived differences between images 👀

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🌸 SYNOPSYS 🌸

no cap, it's literally just this:

butteraugli {image1.(png|jpg|jpeg)} {image2.(png|jpg|jpeg)}
[heatmap.ppm]

two images in, receipts out. that third one is optional, iykyk 💅

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🎀 DESCRIPTION 🎀

so listen. Butteraugli is a project that estimates the psychovisual similarity of two images. yes, psychovisual. it's giving brain-meets-eyeballs fr fr 🧠👁️

it gives you a score for the images, and that score is reliable in the domain of barely noticeable differences. that's the whole flex — it's accurate exactly where it's hardest, when the difference is so tiny you'd barely clock it.

and here's the part that's lowkey iconic: Butteraugli doesn't just give you a scalar score. it also computes a spatial map</> of the level of differences. like, where in the image are things different, not just how different. main character energy for real 👑

now, the motivations, because the lore matters:

• one of the main motivations for this project is the statistical differences in location and density of different color receptors, particularly the low density of blue cones in the fovea. yep, your eyeballs are built weird, and Butteraugli knows 🫶
• another motivation comes from more accurate modeling of ganglion cells, particularly the frequency space inhibition</> ✨

so it's not just "do the pixels match" — it's "would a human notice", modeled properly. obsessed.

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💜 AUTHOR 💜

this manual page was written by ChangZhuo Chen <czchen@debian.org> for the Debian GNU/Linux system — but may be used by others. sharing is caring, slay 💖

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aaaand that's the page bb 🎀 no cap, you now know Butteraugli better than like 90% of people. periodt 💅

this page is from 03/30/2026, filed under BUTTERAUGLI(1) — go forth and measure some perceived differences, bestie 🌈⭐