PSB

Only for genuinely oversized working files — large-format print composites, VFX plates, panoramic stitches — that actually exceed PSD's 30,000px/2GB ceiling. For anything smaller, prefer PSD or a flattened TIFF derivative.

PSB supports documents up to 300,000 x 300,000 pixels and roughly 4 exabytes in file size, compared with PSD's hard ceiling of 30,000 x 30,000 pixels and 2GB. In practice PSB's real limit is disk space and OS file-size handling, not the format spec itself — few working files ever approach the theoretical maximum, but the headroom is what lets Photoshop keep saving once a document outgrows PSD.

No — PSB extends PSD's data model unchanged, with the same lossless compression, color modes, and EXIF/IPTC/XMP/ICC metadata support. It exists purely to remove PSD's size limits, not to add new capabilities.

Rarely, and with caveats. PSB is essentially unsupported outside Photoshop — most third-party editors that read PSD files stop short of PSB, and Adobe's own non-Photoshop apps have historically lacked full support too. GIMP's PSD plug-in can attempt to load a PSB file, but its fidelity for PSB specifically isn't well documented, so layers, adjustment layers, and effects may not survive the round trip. A DAM should test any non-Photoshop viewer before trusting it with production PSB assets.

Because PSB exists specifically for documents whose pixel dimensions and layer counts already broke PSD's limits, a full-resolution render has to decompress far more image data than an average asset — sometimes gigabytes across dozens of layers. Since PSB is essentially unsupported outside Photoshop, most DAM thumbnailing pipelines (built on ImageMagick, libvips, or similar) can't rasterize it directly either, forcing either a slow, resource-heavy full decode or scripted Photoshop automation just to produce a small preview image.

Always generate and store a downsized TIFF or JPEG derivative alongside any PSB master for search and preview purposes, since asking a search index or thumbnail service to open the full PSB on demand is slow and often unsupported outside Photoshop.

Photoshop automatically prompts users to save as PSB once a document crosses PSD's size or dimension thresholds — 30,000 pixels on any side or roughly 2GB of data. That ceiling gets hit organically: stacking many high-resolution layers, working in 16-bit or 32-bit color, merging large panoramic stitches, or building composites with dozens of smart objects all inflate file size well past what PSD can hold, so the save dialog switches formats rather than failing outright.

Print, VFX, and large-format design pipelines are the main source: billboard composites, matte paintings layered with dozens of high-resolution passes, and panoramic stitches that merge many source photos into one continuous canvas. These workflows push pixel dimensions or layer-driven file size past PSD's 30,000px/2GB ceiling as a byproduct of the work itself, not because anyone deliberately chose the format.