compress any image to 16 bytes — and reconstruct it

Algorithm · Demo · Bugs · Contributing

SplatHash encodes any image into exactly 16 bytes (a 22-char base64url string) and decodes it back to a 32×32 blurry preview in 0.067 ms. Go, TypeScript, and Python all produce bit-for-bit identical hashes.

Columns: original · SplatHash 32×32 · ThumbHash · BlurHash. Regenerate: mise run compare.

Install

Language	Package	Docs
Go	go get github.com/junevm/splathash/src/go	src/go/README.md
TypeScript / JS	npm install splathash-ts	src/ts/README.md
Python	pip install splathash-py	src/py/README.md

Go is the reference implementation. All others are verified bit-for-bit against it.

Benchmarks

Go benchmarks on Intel Core i5-9300H (go test -bench=. -benchmem).

	SplatHash	ThumbHash	BlurHash
Decode	0.067 ms	0.50 ms	6.55 ms
Encode	3.53 ms	0.86 ms	445 ms
Decode allocs	7	1,168	5
Bytes	16 fixed	25–37	20–25
String	22 chars	34–50 chars	27–30 chars

Decode runs on every page load for every user. Encode runs once at upload. Optimize for decode.

Raw output

BenchmarkEncodeSplatHash-8      303      3530083 ns/op   100760 B/op   29 allocs/op
BenchmarkEncodeThumbHash-8     1431       863553 ns/op     1015 B/op    6 allocs/op
BenchmarkEncodeBlurHash-8         3    445696421 ns/op 33358234 B/op    8 allocs/op
BenchmarkDecodeSplatHash-8    17182        67622 ns/op    29584 B/op    7 allocs/op
BenchmarkDecodeThumbHash-8     6559       503366 ns/op    58408 B/op 1168 allocs/op
BenchmarkDecodeBlurHash-8       171      6553100 ns/op   547552 B/op    5 allocs/op

Comparison

Feature	SplatHash	ThumbHash	BlurHash
Fixed output size	Yes (16 bytes)	No	No
Storable as 128-bit integer	Yes	No	No
Perceptual color space (Oklab)	Yes	No	No
Spatially localized basis	Yes (Gaussians)	No	No
Global weight optimization	Yes (Ridge)	No	No
Alpha channel support	Yes	Yes	No
Bit-exact cross-language parity	Yes	No	No
Configurable quality vs. size	No	No	Yes

How It Works

Background color + six Gaussian blobs placed by matching pursuit, color-optimized by Ridge Regression, all in Oklab, packed into 128 bits. Full spec: ALGORITHM.md.

Development

mise install     # install Go and Node at pinned versions
mise run test    # run all tests (Go + TypeScript + Python)
mise run bench   # Go benchmarks
mise run compare # regenerate docs/comparison.png

License

See LICENSE.