PCX

PCX is ZSoft's PC Paintbrush format: a 128-byte header, then scanlines of one to four color planes, nearly always run-length coded. It reads and writes through the Egami.Formats.Extended package: register it with WithPcx() or WithExtendedFormats() (Extended formats).

Reads	1, 2, 4 and 8-bit images of one plane; 1-bit images of 2 to 4 planes (EGA, 16 colors); 24-bit (three planes) and 32-bit (four planes, the fourth as alpha); coded or not; runs that carry on into the next scanline
Writes	Version 5, run-length coded: gray rasters as one 8-bit plane with a gray palette, everything else as 24-bit RGB; the resolution in dots per inch (72 when the raster has none)
Natural pixel type	Gray8 for 1-bit and for 8-bit images the header calls gray, Rgba8 for four planes, Rgb8 otherwise
FormatInfo	PcxFormat.Info: name PCX, extension .pcx, MIME types image/vnd.zbrush.pcx and image/x-pcx

Palettes come from the header (16 colors) or, for 8-bit images, from the 769 bytes after the pixels, so an 8-bit file is read to its end before its first row. A 1-bit image of one plane is black where a bit is clear and white where it is set, as its palette says; ImageMagick writes and reads such files the other way round, so its 1-bit PCX files load inverted. A file whose 256-color palette is missing reads as gray levels with the warning Pcx.PaletteMissing.

PcxDetails keeps the version, the bits per pixel, the plane count and the palette.

// What the header said that the pixels do not: PcxDetails, SgiDetails, SunRasterDetails, XbmDetails and XpmDetails.
using Raster image = Raster.Load("arrow.xbm", context);
if (image.Metadata.FormatDetails is XbmDetails xbm)
{
    Console.WriteLine($"{xbm.Name}, hotspot {xbm.Hotspot}");
}

// Writers take the name and hotspot back from the details.
image.Metadata.FormatDetails = new XbmDetails { Name = "pointer", Hotspot = new Point(0, 0) };
image.Save("pointer.xbm");

The files Egami writes have no alpha and no metadata but the resolution; a save that drops alpha or deeper samples says so in the Warnings. Images are at most 65,534 pixels wide and 65,536 high.