PSD (Adobe Photoshop Document)
The native file format of Adobe Photoshop, preserving every layer, mask, and adjustment exactly as you left them.
| Full name | Adobe Photoshop Document |
| Extension | .psd |
| MIME type | image/vnd.adobe.photoshop |
| Developer | Adobe Systems (now Adobe Inc.) |
| Released | 1990 (with Photoshop 1.0) |
| Type | Raster image with layer support |
| Max canvas size | 30,000 × 30,000 pixels (PSB: 300,000 × 300,000) |
| Byte order | Big-endian |
What is a PSD file?
PSD is the native file format of Adobe Photoshop, the industry-standard image editing application first released on February 19, 1990. Unlike flattened image formats, a PSD keeps every layer, mask, channel, and adjustment intact so you can return and keep editing. It is the standard interchange format among professional graphic designers, photographers, and digital artists.
A PSD file is a multi-layer raster image document saved by Adobe Photoshop. It stores pixel data across independent layers, each of which can hold raster content, vector shapes, text, adjustment settings, or smart objects. All those layers remain fully editable after you save and reopen the file. The format also supports up to 32-bit color depth per channel and a wide range of color modes, including RGB, CMYK, Lab, Grayscale, and Duotone.
History
Thomas Knoll began developing what became Photoshop in 1987 as a program to display grayscale images on a Macintosh. His brother John Knoll encouraged him to expand it into a full image editor. Adobe Systems licensed the software and shipped Photoshop 1.0 exclusively for Macintosh on February 19, 1990, with the PSD format as its native document type from the start. Adobe later published a public specification for PSD so third-party applications could read and write the format.
How it works
A PSD file is divided into five sequential sections: the file header, color mode data, image resources, layer and mask information, and the merged image data. The header stores the version number, number of channels, dimensions, bit depth, and color mode. The layer and mask section is the largest part of most files; it contains each layer's pixel data, blending settings, effects, and any vector or text metadata. Data throughout the file is written in big-endian byte order.
What it is used for
- Saving work-in-progress graphic design projects where layers must stay editable
- Handing off layered artwork between designers or to a print shop
- Storing high-resolution product or marketing images with non-destructive adjustment layers
- Archiving original photo retouching work before exporting a flattened JPEG or PNG
How to open it
Adobe Photoshop opens PSD files natively, and Adobe Illustrator can import them as well. Free and paid alternatives that support PSD include GIMP, Affinity Photo, Photopea (browser-based), and CorelDRAW.
Pros and cons
Strengths
- Preserves all layers, masks, smart objects, and adjustments for full re-editability
- Supports high bit depths (up to 32 bits per channel) for professional color work
- Widely recognized by print and digital production workflows
- Adobe publishes a public spec, so many third-party tools can read the format
Trade-offs
- File sizes can be very large, especially with many high-resolution layers
- Not suitable for web delivery or sharing with non-designers
- The public specification is incomplete, so third-party implementations sometimes differ from Photoshop behavior
- No animation or video support (Photoshop uses PSB or PSDT for extended features)
Convert PSD files
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From PSD
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PSD FAQ
What is the difference between PSD and PSB?
PSB (Photoshop Big Document) is an extended version of PSD that supports canvases up to 300,000 × 300,000 pixels and files larger than 2 GB. PSD has a 2 GB file size limit and a 30,000 × 30,000 pixel canvas limit. For most projects, PSD is sufficient; PSB is used for very large prints or panoramas.
Can I open a PSD file without Photoshop?
Yes. GIMP, Affinity Photo, and the browser-based Photopea all open PSD files for free. Some layer effects and smart filters may not render exactly, but the core layer structure is usually preserved.
Does a PSD file lose quality when saved multiple times?
No. PSD is a lossless format, so saving the same file repeatedly does not degrade the pixel data. You only lose quality when you export to a lossy format like JPEG.
Why are PSD files so large?
Photoshop stores uncompressed or lightly compressed pixel data for every layer separately, plus channel data, history states (optionally), and metadata. A single image with ten high-resolution layers can easily reach hundreds of megabytes.