PSD Files

What is a .PSD file?

The PSD is normally an Adobe Photoshop Document format that was invented by the firm Adobe as a native format meant for use with Adobe Photoshop software. The native format's MIME media is image/vnd.adobe.photoshop. Photoshop came into play in 1990 with the introduction of the PSD as a means to edit the art in Photoshop instead of having the file format used for saving only finished artworks.

Pixel layer, layers group, layer mask, vector mask, alpha channels, selections, adjustment layers, type layers, vector objects, Layer Effects, guides, path information, and embedded color profile data may be saved in a PSD. It is frequently employed as either a reusable PSD file, template file, design mockups, workfile, or delivery file format in graphic designs, photographers, printing houses, user interface, and social network media agencies.

The Photoshop format of Adobe .PSD is strongly affiliated to the usage of PSD and .PSB file extensions to represent their documents or projects in binary format. Since most of modern web browsers will display images in formats other than PSD, such as PNG, JPEG, WebP, PDFs and SVG formats and not in PSBs or PSD.

It should be noted that PSB is the large Photoshop document format while the common PSD is just the Photoshop document format. In this regard one might encounter files that were incorrectly renamed and/or damaged to PSD. A real PSD file starts with a "magic cookie" of 8BPS four-byte header signature string.

How to open a .PSD file

Technical details

PSD format is a binary format. The header of the Photoshop PSD starts at offset 0 with the four-character sequence 8BPS represented as hex values 38 42 50 53, followed by 2-byte version number where the standard version is 00 01. However, the versions of the same family include 2 in the version field of PSB - Adobe’s Large Document Format while the PSD specification represents file format version 1. The registered MIME type is image/vnd.adobe.photoshop.

The header contains information about channel count, height and width of the image, bit depth, color mode and is preceded by some reserved data. The limit for PSD file format version 1 is 30,000 by 30,000 pixels practically limited to around 2 GB of the PSD file size. Possible depths range from 1-bit for the image data to 8-, 16-, and 32-bit-per-channels. Valid color modes are Bitmap, Grayscale, Indexed Color, RGB, CMYK, Multichannel, Duotone and Lab modes.

A PSD image consists of five components: the file header; color mode; image resources with the number of tagged blocks that contain embedded ICC profiles, metadata like XMP, EXIF, IPTC/IIM, resolutions data, thumbnail images, printer settings data, guides, slices, clipping path data and others that depend on Photoshop features used during processing; information about layers and masks with layer records, channel descriptors, rectangles, blend modes data, alpha channels, and channel offsets; actual image pixel data, which can be stored separately for each layer.

The compression algorithms use raw uncompressed data, packbits-style RLE compression, ZIP compression with or without prediction. As the composite preview, layer preview and pixel adjustment data are included, typical sizes of the PSD files range up to 2 GB.

How to convert .PSD files

Export your PSD as PNG if the intention for the result is going to be a final file with transparency, such as a web icon or any user interface element of any application or website you want to publish. You can use ImageMagick in the following process to convert a merged composite PSD file into PNG using the command magick 'input.psd[0]' output.pngCopy because the [0] tells ImageMagick you just want to render a flattened version of your file, and not create a new picture of all PSD layers, masks etc., like a layer of its own. It must be remembered that transparency is supported by PNG, although layers, masks, adjustment layers, and even editable text are rendered into flat objects inside PNG if they weren't exported out by any application such as Photoshop, Photopea, or Affinity Photo.

Export to JPEG only if a preview is needed for emailing proofs of photographs to your client. If you have a layered image but no specific intention to do some future edits, just export JPEG for photographic previews and email proofs. In this process, ImageMagick uses the following command: magick 'input.psd[0]' -background white -alpha remove -alpha off -quality 90 output.jpg.Copy The main things to know about JPEG files: it is a lossy format and it doesn’t support transparency or layers.

Common problems and fixes

"Could not complete your request because it is not a valid Photoshop document" - if such notification appears on screen, the most likely problem is file corruption or damage. Real PSD file should begin with a 4-byte 38 42 50 53 header with an offset of 0 in hex. If there is no such a sequence "8BPS" at that offset in a hex editor, the Photoshop file is invalid and one should restore backup copies or ask the sender to prepare new PSD.

"Could not open ... because the file is not compatible with this version of Photoshop" notification means the PSD was prepared by using some more recent functions of Photoshop program which is not available in the version used for viewing the image (e.g. the file uses some features from Adobe Photoshop CC, but you are trying to view it in CS4).

"Could not complete your request because an unexpected end-of-file was encountered" error message appears due to unfinished download procedure, failed synchronization with remote cloud services, broken disk blocks, or file was downloaded via FTP or mail server incompletely or was partially sent by email. Partially saved Photoshop documents often can not be viewed properly by Photoshop or open with problems.

Notifications "Out of memory" and "All scratch disks are full" often occur due to very big layered photos that have many elements. One needs freeing of disk space, changing of Photoshop Preferences regarding scratch-disks, closing of unnecessary programs, or preparing of flattened PSD file from the side of sender (in the absence of Photoshop license). Missing fonts also lead to line breaking. To fix this problem, use of original fontset, outlined texts or flattened images is necessary.

The file that is not opened correctly by using GIMP, Krita or Photopea programs may contain only composite preview or those programs flatten all layers, adjustment layers, smart object layers, vector mask layers, layer-comps, etc. Missing of color profile in Photoshop causes incorrect colors of layers.

Security considerations

Unlike macros in Microsoft Office products, or PDF JavaScript, PSD files aren't executable but rather a type of a binary graphic document, meaning that general risk is less compared to such potentially dangerous components as DOCM, XLSM, PScript packages and PDF JavaScript. But for parsers - like Photoshop, GIMP, ImageMagick - parsing PSD is risky in the terms of processing complex format of PSD image. So use your current software for reading PSD files in case of doubt.

The PSD files can include some personal information as well as private data and metadata in XMP, IPTC or EXIF formats: photo properties, information about creator, copyright messages, geotags, software version numbers, edit history, thumbnails and other useful data for color management process. In addition, the so called smart objects or linked assets embedded in such file can contain other image and text files pointing out to source files.

Some really big and strange-looking (or just wrongly processed) PSD files can crash applications, which work with PSD (especially those working in batch process) by wasting all resources. Don't install any new fonts (in case if they will be sent along with PSD), Photoshop's plug-ins or actions for Photoshop. When transferring to others, provide an exported, metadata-stripped flat image.

History and versions

Photoshop 1.0 was launched for the Macintosh back in 1990 after the development of such software by Thomas Knoll and John Knoll; at the same time, Photoshop received its file format PSD. Photoshop 3.0 was introduced four years later with layer support thus turning PSD into the production-ready editable file format.

In the 1990s, various updates brought better color management, tools for the Web production, enhanced editing types, metadata; all such information is stored inside Photoshop resource block data structure. Within the Creative Suite period of life of Photoshop, software evolved non-destructive editing in the shape of smart objects, layer styles evolution, PSD alternative in form of Large Document Format (PSB) with file format of version 2 compared to regular PSD file format version 1.

Specification of the Photoshop file format can be found at the official page of Adobe developers site, still it does not mean that Photoshop PSD is an ISO or W3C standard but rather proprietary format belonging to Adobe Inc. Thanks to wide usage of PSD in design workflow it was becoming de facto format and many software third parties implemented it as PSD reader/writer in addition to their core functionality. Still Photoshop Creative Cloud versions supports reading/writing of current PSD version; other software may flatten it during import and may skip some advanced features.

Related formats

The Large Document Format in the Adobe suite refers to PSB (version 2 of the Photoshop file format). Use .psb in place of .psd once you exceed its limits of either being 2 GB or 30,000 pixels in size, but remember .psb compatibility in other programs is likely to be worse than with .psd. As far as TIFF is concerned, while providing support for color managed lossless compression, it is much better at transferring printing raster graphics because of having a standard box around your images compared to .psd.

JPEG and JPG represent convenient compressed versions of photography; although significantly small compared to the above, their lossy nature makes them unfit to be an editing master format as opposed to PNG (also compressed losslessly, web friendly, transparency supporting) and TIFF. While JPEG, WEBP and AVIF serve perfectly well as optimized formats for transferring on the Internet - they are output-only. KRA is used specifically in Krita, while ORA OpenRaster stands for layer-wise image interchange - use PSD with other people who will edit the same image in Photoshop.

As a matter of fact, when you require scalability rather than editing functionality, AI (Illustrator specific extension), SVG (scalable vector graphics) and even PDF (Portable) might prove to be useful.