Image MIME Reference
AVCS
AVC Image Sequence (HEIF Container)
image/avcs
VS
Global Graphics Page Graphics Buffer
image/vnd.globalgraphics.pgb
Harlequin-PGB
A complete technical comparison of AVC Image Sequence (HEIF Container) and Global Graphics Page Graphics Buffer — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | AVCS | Harlequin-PGB |
|---|---|---|
| Transparency (Alpha) | Yes | ✕ No |
| Animation Support | Yes | ✕ No |
| Progressive Loading | ✕ No | ✕ No |
| HDR Support | Yes | ✕ No |
| EXIF Metadata | Yes | ✕ No |
| ICC Color Profile | Yes | Yes |
AVC Image Sequence (HEIF Container)
image/avcs
Extension
.avcs.heifs
Container
HEIF / ISOBMFF (ISO/IEC 14496-12)
Compression
Lossy / Lossless
Algorithm
AVC (Advanced Video Coding / H.264)
Color Depth
8-bit, 10-bit, 12-bit
Developed by
Moving Picture Experts Group (MPEG) / ISO/IEC JTC 1
Released
2015
Magic Bytes
XX XX XX XX 66 74 79 70 61 76 63 73
Global Graphics Page Graphics Buffer
image/vnd.globalgraphics.pgb
Extension
.pgb
Container
Proprietary Harlequin Raster Container
Compression
Uncompressed / Run-Length Encoding (RLE)
Algorithm
Proprietary RLENone
Color Depth
1-bit (Monochrome Separations), 8-bit (Grayscale), 8-bit/10-bit (Contone), CMYK / N-Color Spot Channels
Developed by
Global Graphics Software (Hybrid Software Group)
Released
1990s
Magic Bytes
Unknown (Proprietary Harlequin Header)
Browser Support Comparison
| Browser | AVCS | Harlequin-PGB |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ | ✕ |
AVCS
AVCS Strengths
- Efficiently stores bursts of images or animations utilizing inter-frame compression
- Leverages the highly compatible and widely hardware-accelerated AVC (H.264) codec
- Robust HEIF container supports extensive metadata, alpha channels, and depth maps
Limitations
- Zero native support in web browsers
- Largely superseded in efficiency by newer sequence formats like HEICS (HEVC) or Animated AVIF (AV1)
- Complicated container structure requires specialized parsing libraries
Harlequin-PGB
Harlequin-PGB Strengths
- Unlike generic 1-bit TIFFs, PGB files inherently encapsulate vital print-job metadata within their headers (e.g., job name, page number, separation colors, screening angles)
- Highly optimized for ultra-fast viewing and processing within professional printing workflows
Limitations
- Completely proprietary and closed-source, locking its usage strictly to Harlequin-powered RIP environments
- Zero support in standard desktop operating systems, web browsers, or consumer image editing software like Photoshop or GIMP
When to choose which format
AVCS
Use AVCS when…
- Burst Photography
- Short Animations
- Camera Capture
- Archival Storage
Harlequin-PGB
Use Harlequin-PGB when…
- Commercial Printing Output
- Computer-to-Plate (CTP) Manufacturing
- Prepress Soft Proofing (e.g., FirstPROOF)
- Harlequin RIP Spooling Pipelines