Convert Photoshop PSD to PPM / PNM

The Photoshop Document (PSD) is the proprietary file format of Adobe Photoshop, capable of storing an image with support for all available imaging options including layers, adjustment layers, layer masks, alpha channels, paths, and vector text. It utilizes Run-Length Encoding (RLE) for compression and allows for a maximum file size of 2 GB and dimensions up to 30,000 pixels. The format maintains the editing history and non-destructive elements of a project, unlike flattened raster formats. The internal structure is divided into five parts: File Header, Color Mode Data, Image Resources, Layer and Mask Information, and Image Data.

Adobe Photoshop is the primary software for full PSD support. However, several other programs offer varying degrees of compatibility. GIMP (GNU Image Manipulation Program) and Paint.NET (with a plugin) can open PSD files but may not render complex layer styles or adjustment layers correctly. CorelDRAW and Affinity Photo also provide robust support. For simple viewing without editing, standard image viewers like XnView or IrfanView can often display the flattened composite preview embedded within the file.

The Portable Pixel Map (PPM) format is a lowest-common-denominator color image format developed by Jef Poskanzer as part of the Netpbm project. It stores pixels as uncompressed RGB triplets (Red, Green, Blue) in either a plain ASCII text format (P3 header) or a more efficient binary format (P6 header). The file structure is extremely minimal, consisting of a magic number identifier, dimensions (width and height), maximum color value, and the pixel data itself, making it easily parsable by simple scripts but inefficient for storage compared to compressed formats like JPEG or PNG.

Native support for PPM files is absent in standard Windows or macOS photo viewers. Users typically require specialized image manipulation software to view or convert these files. GIMP (GNU Image Manipulation Program) and IrfanView are the primary tools for opening PPM files on desktop environments. On Linux systems, the Netpbm toolkit and ImageMagick suite provide command-line utilities for processing and converting PPM data.