Skip to content

image-ppm.md

Latest commit

 

History

History
80 lines (50 loc) · 2.08 KB

image-ppm.md

File metadata and controls

80 lines (50 loc) · 2.08 KB

image-ppm — Netpbm Format Encoder & Decoder

import('image-ppm') provides encode/decode helpers for the Netpbm family of image formats: PPM (RGB), PGM (grayscale), and PBM (bitmap), in both binary and ASCII variants.

Quick Start

ppmLib := import('image-ppm')

// Encode a binary PPM (P6) image
pixels := [[255, 0, 0], [0, 255, 0], [0, 0, 255], [255, 255, 255]]
data := ppmLib.ppm(2, 2, pixels)

// Decode a PPM file
result := ppmLib.decodePPM(data)
// result.width, result.height, result.pixels

// Encode grayscale PGM
grayPixels := [0, 64, 128, 255]
data := ppmLib.pgm(2, 2, grayPixels)

// Encode bitmap PBM
bits := [1, 0, 0, 1]
data := ppmLib.pbm(2, 2, bits)

PPM (RGB Color)

ppm(width, height, pixels)

Encodes a P6 (binary) PPM image. Pixels are a flat row-major list of [r, g, b] lists or 3-byte strings.

ppmPlain(width, height, pixels)

Encodes a P3 (ASCII) PPM image. Same pixel format.

decodePPM(data)

Decodes a P3 or P6 PPM file. Returns {width, height, pixels} where pixels are [r, g, b] lists.

PGM (Grayscale)

pgm(width, height, pixels)

Encodes a P5 (binary) PGM image. Pixels are a flat row-major list of integers [0..255].

pgmPlain(width, height, pixels)

Encodes a P2 (ASCII) PGM image.

decodePGM(data)

Decodes a P2 or P5 PGM file. Returns {width, height, pixels} where pixels are integers.

PBM (Bitmap)

pbm(width, height, pixels)

Encodes a P4 (binary) PBM image. Pixels are a flat row-major list of 0 (white) or 1 (black).

pbmPlain(width, height, pixels)

Encodes a P1 (ASCII) PBM image.

Format Summary

Magic Format Type Channels
P1 PBM ASCII Bitmap 1-bit
P2 PGM ASCII Grayscale 8-bit
P3 PPM ASCII RGB 3×8-bit
P4 PBM Binary Bitmap 1-bit
P5 PGM Binary Grayscale 8-bit
P6 PPM Binary RGB 3×8-bit

Notes

  • Maximum sample value is 255 for PPM/PGM.
  • Decoders automatically skip comments (#) and whitespace in headers.
  • Binary formats are more compact; ASCII formats are human-readable.