Photoshop File Format ((new)) Jun 2026

The Adobe Photoshop File Format (PSD) is the de facto standard for digital image editing and graphic design. Unlike raster-only formats such as JPEG or PNG, PSD is a hybrid container that supports a rich model of layers, masks, blending modes, vector shapes, and non-destructive adjustments. This paper examines the internal architecture of the PSD format, including its file header, color mode data, image resources, and the crucial layer and mask information blocks. It analyzes how the format achieves backward compatibility and handles compression (RLE, ZIP). Finally, it discusses the interoperability limitations of PSD in open-source software and the emergence of the extended PSB format for large documents.

| Format | Layer Support | Compression | Open Standard | Max Dimensions | |--------|---------------|-------------|---------------|----------------| | | Full (masks, styles, adjustments) | RLE, ZIP | No (but documented) | 30,000 px (PSB: 300k) | | TIFF | Basic (multi-page as layers) | LZW, ZIP, JPEG | Yes | 4 GB (BigTIFF: 18 EB) | | OpenEXR | Multi-part (layers as channels) | PIZ, B44, DWAA | Yes (ILM) | Unlimited (64-bit) | | Krita .kra | Full (vector, filters) | ZIP (internal) | Yes (XML+zip) | 100k px | photoshop file format

| Section | Description | |---------|-------------| | | Fixed-length (26 bytes). Contains signature ("8BPS"), version (1 for PSD, 2 for PSB), channel count, dimensions, color mode, and bit depth. | | Color Mode Data | Variable length. Stores color settings (e.g., CMYK profiles, indexed color tables). Usually small. | | Image Resources | Variable length. Holds metadata: thumbnails, guides, layer groups, resolution info, and print settings. | | Layer and Mask Information | The most complex section. Contains layer records, layer masks, adjustment layers, vector masks, and blending ranges. | | Image Data | The final composite image (flattened) in compressed or raw form. | The Adobe Photoshop File Format (PSD) is the

A PSD file is composed of five major sections, in order: It analyzes how the format achieves backward compatibility

A standard PSD file is capped at a maximum resolution of 30,000 x 30,000 pixels and a total file size of 2 GB .

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