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Image MIME Reference
HEIF-Sequence

High Efficiency Image File Format Sequence

image/heif-sequence
VS

Truevision TGA (Legacy MIME Alias)

image/x-tga
TGA

A complete technical comparison of High Efficiency Image File Format Sequence and Truevision TGA (Legacy MIME Alias) — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature HEIF-Sequence TGA
Transparency (Alpha) Yes Yes
Animation Support Yes ✕ No
Progressive Loading ✕ No ✕ No
HDR Support Yes ✕ No
EXIF Metadata Yes ✕ No
ICC Color Profile Yes ✕ No
High Efficiency Image File Format Sequence
image/heif-sequence
Extension
.heifs.heif.hif
Container HEIF / ISOBMFF (ISO/IEC 14496-12)
Compression Lossy / Lossless
Algorithm
Codec Agnostic (HEVC, AVC, JPEG, AV1)
Color Depth 8-bit, 10-bit, 12-bit, 16-bit
Developed by Moving Picture Experts Group (MPEG)
Released 2015
Magic Bytes
XX XX XX XX 66 74 79 70 6D 73 66 31
Full HEIF-Sequence reference →
Truevision TGA (Legacy MIME Alias)
image/x-tga
Extension
.tga.icb.vda.vst
Container Truevision TGA Footer/Header
Compression Uncompressed / Run-Length Encoding (RLE)
Algorithm
NoneRLE
Color Depth 8-bit (Grayscale or Indexed), 16-bit (High Color), 24-bit (True Color), 32-bit (True Color with Alpha Channel)
Developed by Truevision Inc.
Released 1984
Magic Bytes
54 52 55 45 56 49 53 49 4F 4E 2D 58 46 49 4C 45 2E 00 (At the end of the file)
Full TGA reference →

Browser Support Comparison

Browser HEIF-Sequence TGA
Chrome Chrome
Firefox Firefox
Safari Safari
Edge Edge
IE IE (Legacy)
HEIF-Sequence

HEIF-Sequence Strengths

  • Codec-agnostic container allows for extreme flexibility when storing multi-frame photographic data
  • Maintains the space-saving benefits of ISOBMFF shared frame data blocks
  • Excellent for archiving computational photography workloads like exposure brackets or focal stacks
Limitations
  • Codec ambiguity means a decoder might be able to parse the container but fail to decode the underlying pixels
  • Zero native web browser support
  • Complex container structure requires specialized parsing libraries to extract individual frames
TGA

TGA Strengths

  • Incredibly simple byte layout allows developers to write custom loaders and exporters in a few dozen lines of code, bypassing the need for heavy external libraries
  • Native support for 8-bit alpha channels ensures flawless transparency masking for real-time 3D rendering
  • Fast, predictable RLE decoding requires almost no CPU overhead compared to DEFLATE (PNG) or DCT (JPEG)
Limitations
  • RLE compression is relatively weak by modern standards, resulting in large file sizes
  • Lacks a standard magic byte header at the beginning of the file, making file-sniffing unreliable for older v1.0 files
  • Zero support in web browsers; must be converted to PNG or WebP for web delivery

When to choose which format

HEIF-Sequence
Use HEIF-Sequence when…
  • Burst Photography
  • Focal Stacking
  • Exposure Bracketing
  • Time-Lapse Data
TGA
Use TGA when…
  • Video Game 3D Textures and Materials
  • 3D Rendering and Animation Sequences
  • Legacy Video Production Workflows
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