tga

Go package for decoding and encoding TGA (Truevision TARGA) images.

• Decode: uncompressed and RLE image types 1, 2, 3, 9, 10, 11; bit depths 8, 15, 16, 24, 32.
• Encode: grayscale, true-color (16/24/32), and paletted (8) output; optional RLE compression.
• TGA 2.0 read support: footer, extension/developer areas, metadata, and postage-stamp thumbnails.
• TGA 2.0 write support: footer, extension/developer areas, and metadata fields.
• Encode options: PixelDepth, ColorMapDepth, OriginBottom, ImageID.

Decode output types are specialized by format:

• *image.Gray for Gray8,
• *image.Paletted for indexed images,
• *image.NRGBA for true-color and Gray16.

TGA 2.0 premultiplied alpha metadata returns *image.RGBA.

Note

TGA has no stable magic bytes, so global registration via image.RegisterFormat can conflict with other decoders. Use direct tga.Decode/tga.DecodeConfig by default. If you still need image.Decode, opt in with blank import: import _ "github.com/woozymasta/tga/register".

Install

go get github.com/woozymasta/tga

Usage

import "github.com/woozymasta/tga"

// Decode (direct; no registration)
img, err := tga.Decode(r)
cfg, err := tga.DecodeConfig(r)

// To use image.Decode with TGA: import _ "github.com/woozymasta/tga/register"

// Decode with resource limits for untrusted input.
img, err := tga.DecodeWithOptions(r, tga.DecodeOptions{
  MaxPixels:       16 * 1024 * 1024,
  MaxDecodedBytes: 64 * 1024 * 1024,
})

// Decode TGA 2.0 metadata, including optional thumbnails, from a seekable reader.
img, info, err := tga.DecodeWithMetadata(readSeeker)

// Encode
err := tga.Encode(w, img)

// Encode with RLE compression
err := tga.EncodeWithOptions(w, img, &tga.EncodeOptions{RLE: true})

// Encode true-color as 24-bit
err := tga.EncodeWithOptions(w, img, &tga.EncodeOptions{PixelDepth: 24})

// Encode true-color as 16-bit
err := tga.EncodeWithOptions(w, img, &tga.EncodeOptions{PixelDepth: 16})

// Encode paletted image with 32-bit palette entries
err := tga.EncodeWithOptions(w, palettedImg, &tga.EncodeOptions{ColorMapDepth: 32})

// Encode with TGA 2.0 metadata (footer + extension/developer areas)
err := tga.EncodeWithOptions(w, img, &tga.EncodeOptions{
  Metadata: &tga.TGA2Metadata{
    Author:    "WoozyMasta",
    Gamma:     2.2,
    Timestamp: time.Now(),
  },
})

// Encode with bottom-left origin and Image ID field
err := tga.EncodeWithOptions(w, img, &tga.EncodeOptions{
  OriginBottom: true,
  ImageID:      []byte("preview-id"),
})

// Set explicit TGA2 alpha-attribute semantics (advanced)
err := tga.EncodeWithOptions(w, img, &tga.EncodeOptions{
  Metadata: &tga.TGA2Metadata{
    AttributesType: 3,
  },
})