pamtotga

Convert a Netpbm image to a TrueVision Targa file

$ pamtotga [path/to/file.pam] > [path/to/output.tga]

$ pamtotga -[cmap|cmap16|mono|rgb] [path/to/file.pam] > [path/to/output.tga]

$ pamtotga [[-v|-version]]

pamtotga [<pamfile>]
pamtotga [-alphacolor=<color>] [<pamfile>]

pamfile
    The input Portable Arbitrary Map (PAM) image file. If not specified, pamtotga reads from standard input (stdin).

-alphacolor=<color>
    Specifies a background color to use for transparent pixels if the input PAM image has an alpha channel. The color can be specified as a hexadecimal RGB value (e.g., #RRGGBB) or a recognized color name. If omitted, the output TGA will typically retain the alpha channel.

The pamtotga command is a crucial utility within the Netpbm image processing suite, designed specifically for converting images from the Portable Arbitrary Map (PAM) format to the Truevision Targa (TGA) format. PAM is Netpbm's generic pixelmap format, capable of representing a wide range of pixel data, including grayscale, color, and alpha channels. TGA, on the other hand, is a popular raster graphics format, widely used in video editing, 3D graphics, and game development due to its support for various bit depths and an optional alpha channel.

When pamtotga processes a PAM image, it reads the pixel data, colorspace, and alpha channel information, then translates it into a TGA file structure. If the input PAM contains an alpha channel, pamtotga typically produces a 32-bit TGA image that preserves this transparency. Users can also specify a background color for transparent areas using the -alphacolor option, which can be useful when compatibility with older TGA viewers or specific visual requirements are paramount. This command is often used as part of a larger pipeline, where an image is first converted to PAM for manipulation and then to TGA for final output or use in other applications.

• pamtotga focuses primarily on image data conversion and does not support TGA-specific features like image origin or gamma correction.
• While TGA supports RLE compression, pamtotga usually outputs uncompressed TGA files. For compressed output, an external tool might be needed after conversion.
• The -alphacolor option is only relevant if the input PAM image actually contains an alpha channel; otherwise, it is ignored.

Like most Netpbm commands, pamtotga operates as a filter. If no input pamfile is specified, it reads the PAM image data from standard input (stdin) and writes the resulting TGA image to standard output (stdout). This design facilitates its use in pipelines, combining multiple Netpbm utilities for complex image transformations.

The Targa format can support an alpha (transparency) channel. When pamtotga converts a PAM image with an alpha channel, it typically generates a 32-bit TGA file that includes this alpha information. This allows the converted image to maintain its transparency when used in applications that support 32-bit TGA. The -alphacolor option offers a way to 'flatten' this transparency against a solid background color if a 24-bit TGA or specific visual effect is desired.

pamtotga is an integral part of the Netpbm project, a long-standing and widely used toolkit for image manipulation. The Netpbm suite originated from the Pbmplus package in the late 1980s, which introduced the Portable Bitmap (PBM), Portable Graymap (PGM), and Portable Pixmap (PPM) formats. The more flexible Portable Arbitrary Map (PAM) format, which pamtotga processes, was introduced later as a superset of the earlier formats, allowing for arbitrary numbers of channels and bit depths, including alpha transparency. pamtotga was developed to provide robust conversion capabilities to the Targa format, leveraging PAM's comprehensive data representation for seamless image pipeline integration, ensuring compatibility between Netpbm's internal processing and external applications requiring TGA input.

pam(5), tga(5), tgatoppm(1), anytopnm(1), pnmgamma(1), pnmcolormap(1)