Photoshop Large Document Format (.psb)
Adobe StandardPhotoshop Large Document Format (PSB) is Adobe Photoshop's 64-bit large-canvas format, designed to support massive graphics files up to 300,000 pixels in dimension and file sizes exceeding standard 2 GB limits.
Convert PSB to PNG
Free in-browser PSB to PNG converter. Convert files instantly on your device.
Inspect & Metadata
Operating systems and file analyzers identify PSB files by inspecting the leading binary byte sequence:
Byte-Level Header Signature (Magic Bytes)
Operating systems and file analyzers identify PSB files by inspecting the leading binary byte sequence:
HEX SIGNATURE (OFFSET 0):
38 42 50 53 00 02ASCII REPRESENTATION: 8BPS..
Standardization: Adobe Photoshop File Format Specification (Version 2)
Technical Specifications
| Container Architecture | Photoshop document structure using 64-bit file offsets and length descriptors (Version 2) |
| Compression | RLE (PackBits), ZIP without prediction, ZIP with prediction, or uncompressed raw planar bytes |
| Byte Endianness | Big-Endian (Motorola byte order) |
| Color Spaces | sRGB, Adobe RGB, ProPhoto RGB, CMYK, Lab Color, Embedded ICC Profiles |
| Channels & Structure | Unlimited layers, masks, smart objects, adjustment layers, text paths, and alpha channels |
| Max Dimensions | 300,000 x 300,000 pixels (up to 4 Exabytes theoretical file size) |
| Transparency | Full multi-layer 8-bit, 16-bit, or 32-bit floating-point alpha blending |
| Streaming & Progressive | Non-streamable multi-layer hierarchical document database |
Technical Comparison Matrix: PSB vs Competitors
| Technical Attribute | PSB (Current) | PSD | TIFF | PNG |
|---|---|---|---|---|
| Maximum Dimensions | 300,000 x 300,000 pixels | 30,000 x 30,000 pixels | Supports BigTIFF 64-bit limits | Supports 31-bit integer limits |
| Maximum File Size | Practically unlimited (up to 4 Exabytes) | 2.0 Gigabytes (32-bit offset limit) | 4.0 GB (standard) / Exabytes (BigTIFF) | 2.0 Gigabytes |
| Internal Offsets | 64-bit file offsets (Version 2) | 32-bit file offsets (Version 1) | 32-bit (standard) / 64-bit (BigTIFF) | 32-bit chunk lengths |
| Layer Preservation | 100% Photoshop layer database | 100% Photoshop layer database | Limited TIFF layer blocks | Flattened single-image raster |
Common Corruption Modes & Hex Recovery Guide
Photoshop displays 'Could not complete your request because it is not a valid Photoshop document'.
Root Cause: Corrupted 64-bit layer offset pointer or unexpected file truncation during saving.
Recovery: Extract flattened composite preview image using File2File PSB Extractor.
Security Analysis & Parser Attack Vectors
PSB files contain complex 64-bit layer hierarchies where corrupted length descriptors can cause memory exhaustion in image parsers.
Known Attack Vectors
- Integer overflow during 64-bit layer mask allocation.
- Buffer over-read when parsing PackBits compressed channel data.
- Denial of service through multi-gigabyte memory allocation triggered by crafted canvas dimensions.
Defensive Best Practices: Validate layer record offsets and apply bounded memory allocation limits during parsing.
Historical Origins & Milestones
Key Advantages & Pros
- Breaks the 30,000-pixel dimension limit and 2 GB file size barrier of standard PSD files (supports up to 300,000 pixels).
- Preserves 100% of non-destructive Photoshop layers, vector paths, Smart Objects, filters, and adjustment layers.
- The industry standard for giant billboards, panoramic murals, building wraps, and gigapixel photography.
Technical Limitations & Cons
- Massive file sizes (often 5 GB to 50 GB per master document), requiring immense RAM and disk space.
- Limited support in non-Adobe applications compared to standard PSD.
- Slow save and load times when writing multi-gigabyte layer databases to disk.
Interesting Technical Trivia
- The magic bytes for a standard PSD end with 0x00 0x01 (Version 1), while a PSB file ends with 0x00 0x02 (Version 2).
- A 300,000 x 300,000 pixel image printed at 300 DPI would span an astonishing 83 feet by 83 feet (25 meters by 25 meters).
- Astrophotographers and NASA composite massive multi-gigapixel telescope panoramas in PSB format.
Frequently Asked Technical Questions
What is the difference between PSD and PSB?
PSD is limited to 30,000 x 30,000 pixels and 2 GB in file size. PSB uses 64-bit offsets to support images up to 300,000 x 300,000 pixels and file sizes well into the hundreds of gigabytes.
When should I use PSB instead of PSD?
Photoshop will prompt you to save as PSB whenever your image exceeds 30,000 pixels in either dimension or exceeds 2 GB in file size.
How can I convert a PSB file to JPG or PNG?
You can convert PSB documents into flattened JPG or PNG images using File2File.app directly in your browser.