TIFF to PCX Converter

Encoding: the TIFF uses none, LZW, PackBits, Deflate or JPEG, chosen per file; PCX uses byte-wise run-length encoding, and the download is a run-length encoded PCX: 8-bit indexed when the image has 256 colours or fewer, otherwise 24-bit RGB.

Bit depth: 1 to 16 bits per channel, or 32-bit floating point in the TIFF; PCX allows 1, 2, 4 or 8 bits per pixel with a palette, or 24-bit as three 8-bit planes, and the PCX written here has 8-bit indexed or 24-bit RGB. 16-bit and floating-point TIFFs are reduced to 8 bits per channel.

Colour: RGB, CMYK, Lab, greyscale or palette, often with an ICC profile in the TIFF; PCX supports a 16 or 256-colour palette, or 24-bit RGB, written here as 8-bit sRGB.

Transparency: the TIFF stores it as an extra sample declared in the ExtraSamples tag; the PCX has none, so transparent areas are filled with the colour you choose.

Other images: the TIFF can hold several pages, each in its own image file directory; only the main image is converted.

Metadata: the TIFF can carry EXIF, XMP, IPTC and ICC, all stored as tags; PCX can carry only a 128-byte header with the resolution, but nothing is copied across.

TIFF is the professional archive and print format. It can hold multiple pages, high bit depths and lossless data, and is common in scanning, publishing and GIS.

A TIFF begins with 'II' or 'MM' for the byte order and the number 42, then an offset to the first image file directory (IFD): a table of tags giving the size, compression, colour model and the location of the strips or tiles of pixels. Each further page is another IFD.

TIFF files usually come from scanners, print and publishing workflows, photo archives and tethered camera capture.

PCX is the image format of ZSoft's PC Paintbrush, the standard for DOS paint programs, scanners and games before GIF and BMP took over. It compresses with a simple run-length scheme.

A PCX file has a 128-byte header (the byte 0x0A, version, encoding, bits per pixel, image window, DPI, a 16-colour palette and the number of colour planes), then RLE-compressed scanlines; 256-colour files end with the byte 0x0C and a 768-byte palette.

PCX is the better choice for DOS-era software, retro games and old fax or scanner tools, while TIFF suits printing, scanning and archival masters.

PCX strengths: Read by most legacy and modern viewers; Simple, lossless run-length compression. Drawbacks to weigh: Poor compression for photographs; No transparency; Obsolete outside retro software.