Adobe Photoshop Document
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What is a PSD file?
A PSD file is an image file created by Adobe Photoshop, a professional image-editing program used to enhance digital photos and create web graphics. It is the native format used to save files in Photoshop. PSD files may include image layers, adjustment layers, layer masks, annotations, file information, keywords, and other Photoshop-specific elements. They are commonly created and shared among graphics professionals.
You can modify PSD layers and other elements such as images, shapes, text, and effects. The PSD format supports RGB, CMYK, grayscale, monochrome, duotone, indexed color, Lab color, and multichannel color modes. The color mode can be changed within the Image → Mode submenu. When you are ready to publish the image, you can export it to standard image formats such as .JPEG, .GIF, and .PNG.
The data structure of a PSD file
The Photoshop file format is separated into five major parts:
- File Header - contains the basic properties of the image such as the version, number of channels in the image, number of bits per channel, pixel height and width of the image, and the color mode of the file (bitmap, grayscale, RGB, CMYK, Multichannel, indexed, duotone, and lab).
- Color Mode Data - specifies the length of the color data, which is set to 0 unless the color mode is indexed or duotone as specified in the file header. If this is the case, the indexed color and duotone image color data are also stored in this section.
- Image Resources - specifies the length of the image resource section and the image resources, which is a series of blocks, each with a resource ID that indicates the type of data stored in the block. These blocks store non-pixel data associated with the image, such as pen or pencil tool paths.
- Layer and Mask Information - contains information about layers and masks, which includes the number of layers, channels in the layers, blending ranges, adjustment layer keys, effects layers, and mask parameters.
- Image Data - contains the actual image data and the data compression method and the image pixel data. Different compression methods may be raw image data, RLE compression, Zip without prediction, or Zip with prediction.
NOTE: The PSD format supports a maximum height and width of 30,000 pixels or 2 gigabytes (GB). Images larger than these limits must be saved in the .PSB (Photoshop Big) Large Document format.
How to open a PSD file
You can open PSD files with Adobe Photoshop in Windows and macOS. To open a PSD file in Photoshop, select File → Open.
While PSD files are saved in a proprietary format, you can open them with applications other than Photoshop, such as Adobe Illustrator (multiplatform), Corel Painter (multiplatform), GIMP (multiplatform), and Photopea (in a web browser).
In Windows, you can open PSD files with various media programs if the correct codec, such as the Ardfry PSD codec, is installed. Example applications include Windows Explorer, Windows Photo Viewer, and Windows Media Center.
In macOS, you can open PSD files with Apple Preview, which is bundled with the operating system. To open a PSD file with Preview, select File → Open....
How to convert a PSD file
Several applications, including Adobe Photoshop, Corel PaintShop Pro, GIMP, and Apple Preview, can convert PSD files to other formats.
For example, Adobe Photoshop can convert PSD files to many file types, including the following formats:
- .PSDC - Adobe Photoshop Cloud Document
- .PSB - Photoshop Large Document Format
- .PDF - Portable Document Format
- .JPG - JPEG Image
- .PNG - Portable Network Graphic
- .TIF - Tagged Image File Format
- .GIF - Graphical Interchange Format
- .WEBP - WebP Image
- .AI - Adobe Illustrator Artwork
- .BMP - Bitmap Image
- .DCM - DICOM Image
- .EPS - Encapsulated PostScript