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Image MIME Reference
PaintShop-Pro-PSP

PaintShop Pro Image

image/x-paintshoppro
VS

Progressive JPEG (Legacy IE Alias)

image/pjpeg
PJPEG

A complete technical comparison of PaintShop Pro Image and Progressive JPEG (Legacy IE Alias) — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

PJPEG wins on browser support

Feature Support

Feature PaintShop-Pro-PSP PJPEG
Transparency (Alpha) Yes ✕ No
Animation Support ✕ No ✕ No
Progressive Loading ✕ No Yes
HDR Support Yes ✕ No
EXIF Metadata Yes Yes
ICC Color Profile Yes Yes
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 →
Progressive JPEG (Legacy IE Alias)
image/pjpeg
Extension
.jpeg.jpg.pjpeg.pjp.jfif
Container JPEG (ISO/IEC 10918-1)
Compression Lossy (DCT)
Algorithm
Discrete Cosine Transform (DCT)
Color Depth 8-bit, 12-bit
Developed by Joint Photographic Experts Group / Microsoft (Alias)
Released 1992
Magic Bytes
FF D8 FF E0 (JFIF) / FF D8 FF E1 (Exif)
Full PJPEG reference →

Browser Support Comparison

Browser PaintShop-Pro-PSP PJPEG
Chrome Chrome
✕
✓ All
Firefox Firefox
✕
✓ All
Safari Safari
✕
✓ All
Edge Edge
✕
✓ All
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
PJPEG

PJPEG Strengths

  • Progressive JPEGs (which this MIME type attempted to describe) provide excellent perceived loading speeds on slow connections by rendering a low-resolution preview first
  • Files sent with this MIME type are fully backwards compatible with any standard JPEG decoder
Limitations
  • It is a non-standard MIME type that violates IANA specifications
  • Causes strict file upload validation scripts to fail if not explicitly whitelisted or mapped
  • Creates unnecessary confusion, as the official image/jpeg MIME type already fully encompasses progressive encoding

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)
PJPEG
Use PJPEG when…
  • Legacy Internet Explorer File Uploads
  • Progressive Image Rendering (Historical context)

More comparisons

PaintShop-Pro-PSP vs ACES → PJPEG vs ACES → PaintShop-Pro-PSP vs APNG → PJPEG vs APNG → PaintShop-Pro-PSP vs AVCI → PJPEG vs AVCI → PaintShop-Pro-PSP vs AVCS → PJPEG vs AVCS → PaintShop-Pro-PSP vs AVIF → PJPEG vs AVIF → All comparisons →
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