File extension
.psd
Adobe Photoshop 2.5 File Format
.psd files are Adobe Photoshop documents: Photoshop's native format, preserving layers, masks, channels, adjustment layers, and other editable image data alongside a composite preview.
Known meanings
Formats and reference material for .psd
Adobe Photoshop 2.5 File Format
Adobe Photoshop 2.5 File Format
Adobe Photoshop 3 and 4 File Formats
Adobe Photoshop 3 and 4 File Formats
Adobe Photoshop 3 Plug-in format
Adobe Photoshop 3 Plug-in format
Adobe Photoshop 6.0 File Formats
Adobe Photoshop 6.0 File Formats
Adobe Photoshop SDKs
Adobe Photoshop SDKs
Details
Format notes
Adobe Photoshop Document (PSD)
PSD is the native document format of Adobe Photoshop. Unlike a flattened image format such as JPEG or PNG, a PSD preserves the editable structure of a project: individual layers and layer groups, layer and vector masks, alpha channels, blend modes, adjustment and text layers, layer effects, and color/mode information. It lets an artist reopen a file and continue non-destructive editing, which is why it is a central interchange format across Adobe’s applications and many third-party tools.
The format is well documented and begins with the signature 8BPS. A PSD stores
the image mode (RGB, CMYK, grayscale, Lab, and others) and bit depth, a layer and
mask section describing every layer’s data and metadata, and a merged composite of
the whole image so that programs which do not understand the layer structure can
still display a flattened preview. The related PSB (“large document”) variant uses
the same structure to exceed PSD’s dimension and size limits.
Preservation And Security Notes
For preservation, the layered PSD is the master/editable copy; a flattened export (TIFF, PNG, or JPEG) is a derivative that discards the editing structure, so both are often kept. Because a PSD is a complex binary format with many variable-length, offset-driven blocks, a parser handling untrusted files should validate lengths and dimensions before allocating memory or decoding.
Further Reading
- Adobe Photoshop File Formats Specification:
https://www.adobe.com/devnet-apps/photoshop/fileformatashtml/