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Image MIME Reference
PaintShop-Pro-PSP

PaintShop Pro Image

image/x-paintshoppro
VS

T.38 Fax over IP (FoIP)

image/t38
T.38

A complete technical comparison of PaintShop Pro Image and T.38 Fax over IP (FoIP) — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature PaintShop-Pro-PSP T.38
Transparency (Alpha) Yes ✕ No
Animation Support ✕ No ✕ No
Progressive Loading ✕ No ✕ No
HDR Support Yes ✕ No
EXIF Metadata Yes ✕ No
ICC Color Profile Yes ✕ No
PaintShop Pro Image
image/x-paintshoppro
Extension
.psp.pspimage.tub.pat
Container PSP Chunk-based Format
Compression Uncompressed / RLE (Run-Length Encoding) / LZ77
Algorithm
RLELZ77
Color Depth 8-bit (Indexed), 16-bit (Grayscale), 24-bit (RGB), 32-bit (RGBA), 48-bit (High Color)
Developed by Jasc Software / Corel Corporation (Alludo)
Released 1990
Magic Bytes
7E 42 4B 00
Full PaintShop-Pro-PSP reference →
T.38 Fax over IP (FoIP)
image/t38
Extension
.t38
Container UDPTL or TCP (Network Transport)
Compression Lossless (MH, MR, MMR / T.4, T.6)
Algorithm
MH (Modified Huffman)MR (Modified Read)MMR (Modified Modified Read)
Color Depth 1-bit (Monochrome B&W)
Developed by ITU-T (International Telecommunication Union)
Released 1998
Magic Bytes
None (Network Stream)
Full T.38 reference →

Browser Support Comparison

Browser PaintShop-Pro-PSP T.38
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
PaintShop-Pro-PSP

PaintShop-Pro-PSP Strengths

  • Provides robust, non-destructive editing capabilities with full support for vector layers, adjustment layers, and layer blend modes
  • Historically offered a highly capable and affordable alternative to Adobe Photoshop's PSD format for Windows users
  • Features proprietary support for 'Picture Tubes' (.tub), a unique brush technology that paints sequential or random raster objects along a path
Limitations
  • Deeply proprietary format tied exclusively to the Corel/Alludo ecosystem
  • Third-party software support (like GIMP or ImageMagick) is often limited to parsing older .psp files, frequently failing to render complex layers in modern .pspimage files
  • No support in modern web browsers; must be exported to a flattened web format (JPEG/PNG) for online viewing
T.38

T.38 Strengths

  • Designed specifically to overcome the timing and packet-loss issues that plague traditional fax over standard VoIP audio codecs (like G.711)
  • Reduces bandwidth requirements by transmitting fax protocol data rather than uncompressed audio tones
  • Universally supported by enterprise SIP trunks and Session Border Controllers (SBCs) for FoIP
Limitations
  • Not an actual image file format, causing confusion due to its 'image/' MIME classification
  • Extremely complex to implement correctly over lossy UDP networks (relies on UDPTL redundancy mechanisms)
  • Zero support in web browsers or standard image viewing software

When to choose which format

PaintShop-Pro-PSP
Use PaintShop-Pro-PSP when…
  • PaintShop Pro Multi-layer Project Archival
  • Digital Art and Photo Retouching
  • Picture Tubes (.tub) and Custom Patterns (.pat)
T.38
Use T.38 when…
  • Fax over IP (FoIP) Transmissions
  • SIP/SDP Media Negotiation
  • VoIP Gateways and PBX Systems
  • Enterprise Fax Servers

More comparisons

PaintShop-Pro-PSP vs ACES → T.38 vs ACES → PaintShop-Pro-PSP vs APNG → T.38 vs APNG → PaintShop-Pro-PSP vs AVCI → T.38 vs AVCI → PaintShop-Pro-PSP vs AVCS → T.38 vs AVCS → PaintShop-Pro-PSP vs AVIF → T.38 vs AVIF → All comparisons →
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