Free webp to jpg
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Image MIME Reference
PWG-Raster

PWG Raster Format

image/pwg-raster
VS

Silicon Graphics Image

image/sgi
SGI

A complete technical comparison of PWG Raster Format and Silicon Graphics Image — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature PWG-Raster SGI
Transparency (Alpha) ✕ No Yes
Animation Support ✕ No ✕ No
Progressive Loading ✕ No ✕ No
HDR Support ✕ No ✕ No
EXIF Metadata ✕ No ✕ No
ICC Color Profile ✕ No ✕ No
PWG Raster Format
image/pwg-raster
Extension
.pwg.ras
Container CUPS Raster v2 Container
Compression PackBits (Run-Length Encoding)
Algorithm
PackBits (Apple RLE variant)
Color Depth 1-bit (Monochrome/K), 8-bit (Grayscale), 24-bit (sRGB / Adobe RGB), 32-bit (CMYK)
Developed by IEEE-ISTO Printer Working Group (PWG)
Released 2011
Magic Bytes
52 61 53 32
Full PWG-Raster reference →
Silicon Graphics Image
image/sgi
Extension
.sgi.rgb.rgba.bw.int.inta
Container SGI Image Format
Compression Uncompressed / Lossless (Run-Length Encoding)
Algorithm
RLENone
Color Depth 8-bit, 16-bit (Per Channel)
Developed by Paul Haeberli (Silicon Graphics)
Released 1990
Magic Bytes
01 DA
Full SGI reference →

Browser Support Comparison

Browser PWG-Raster SGI
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
PWG-Raster

PWG-Raster Strengths

  • The undisputed global standard for modern, driverless printing environments, eliminating the nightmare of installing manufacturer-specific print drivers
  • Extremely lightweight to decode on embedded hardware, requiring minimal RAM buffers on the printer side
  • Strict color space and resolution rules guarantee that the printed output will successfully process without syntax errors
Limitations
  • Generates massive file sizes and network payloads compared to vector-based formats like PDF or PostScript, as every page is fully rasterized at 300+ DPI before transmission
  • No support for native rendering in web browsers, image viewers, or graphic design software without specialized CUPS developer tools
  • Cannot store complex metadata, vector text, or layers
SGI

SGI Strengths

  • Pioneered multi-channel and 16-bit per channel imaging capabilities required for high-end 1990s visual effects
  • Extremely robust and simple header structure
  • Reliable Run-Length Encoding provided solid lossless compression for flat-shaded 3D renders
Limitations
  • Completely obsolete for modern web and application development
  • Zero native web browser compatibility
  • Largely replaced by TIFF and OpenEXR in modern professional VFX and 3D pipelines

When to choose which format

PWG-Raster
Use PWG-Raster when…
  • Driverless Network Printing (IPP Everywhere)
  • Apple AirPrint and Mopria Print Service Pipelines
  • CUPS (Common UNIX Printing System) Spooling
SGI
Use SGI when…
  • Legacy 3D Animation & VFX
  • Silicon Graphics IRIX Workflows
  • Historical CGI Archiving

More comparisons

PWG-Raster vs ACES → SGI vs ACES → PWG-Raster vs APNG → SGI vs APNG → PWG-Raster vs AVCI → SGI vs AVCI → PWG-Raster vs AVCS → SGI vs AVCS → PWG-Raster vs AVIF → SGI vs AVIF → All comparisons →
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