Classic run-length encoding algorithm used in TIFF images, PostScript, and early Apple computer systems. Simple but effective for data with runs of identical bytes.
| Property | Value |
|---|---|
| Category | Compression Algorithms |
| Sub-category | Run-Length Encoding |
| Security status | Not classified |
| Complexity | Not specified |
| Inventor | Apple Computer |
| Year | 1984 |
| Origin | 🇺🇸 United States |
| Source | algorithms/compression/packbits.js |
Status: not classified — treat as unverified.
No vulnerabilities are recorded for this implementation.
8 vectors ship with this algorithm and run in the test suite. Byte values are hexadecimal.
Vector 1 — Empty input
| Field | Value |
|---|---|
input |
(empty) |
expected |
(empty) |
Vector 2 — Single byte literal
| Field | Value |
|---|---|
input |
41 |
expected |
0041 |
Vector 3 — Simple run of 3 identical bytes
| Field | Value |
|---|---|
input |
414141 |
expected |
fe41 |
Vector 4 — Three different literals
| Field | Value |
|---|---|
input |
414243 |
expected |
02414243 |
Vector 5 — Run followed by literals
| Field | Value |
|---|---|
input |
41414141424344 |
expected |
fd4102424344 |
Vector 6 — Literals followed by run
| Field | Value |
|---|---|
input |
41424344444444 |
expected |
02414243fd44 |
Vector 7 — Maximum run length (128 bytes)
| Field | Value |
|---|---|
input |
41414141414141414141414141414141 41414141414141414141414141414141 41414141414141414141414141414141 41414141414141414141414141414141 41414141414141414141414141414141 41414141414141414141414141414141 41414141414141414141414141414141 41414141414141414141414141414141 |
expected |
8141 |
Vector 8 — Maximum literal sequence (128 bytes)
| Field | Value |
|---|---|
input |
000102030405060708090a0b0c0d0e0f 101112131415161718191a1b1c1d1e1f 202122232425262728292a2b2c2d2e2f 303132333435363738393a3b3c3d3e3f 404142434445464748494a4b4c4d4e4f 505152535455565758595a5b5c5d5e5f 606162636465666768696a6b6c6d6e6f 707172737475767778797a7b7c7d7e7f |
expected |
7f000102030405060708090a0b0c0d0e 0f101112131415161718191a1b1c1d1e 1f202122232425262728292a2b2c2d2e 2f303132333435363738393a3b3c3d3e 3f404142434445464748494a4b4c4d4e 4f505152535455565758595a5b5c5d5e 5f606162636465666768696a6b6c6d6e 6f707172737475767778797a7b7c7d7e 7f |