pamtotga - convert a Netpbm image to a TrueVision Targa file
pamtotga [-mono|-cmap|-cmap16|-rgb] [-norle] [-name=name [-verhose] [pamfile]
All options can be abbreviated to their shortest unique prefix. You may use two hyphens instead of one to designate an option. You may use either white space or equals signs between an option name and its value.
This program is part of Netpbm(1).
pamtotga reads a PBM, PGM, PPM, or PAM image as input and produces a TrueVision Targa file as output. The PAM image may be either a BLACKANDWHITE, GRAYSCALE, RGB, or RGB_ALPHA image.
To create a TGA image with transparency (i.e. with a transparency mask), use RGB_ALPHA PAM input. Some Netpbm programs that generate images with transparency masks generate them in that format. For another way to create the proper input stream, see pamstack(1).
It is unclear that anything except pamtotga knows about TGAs with transparency. The history behind this feature of pamtotga is not clear. The format pamtotga produces is simply the same as an ordinary RGB TGA image except with a 4th plane added for transparency. The PixelSize field of the TGA header specifies 32 bits instead of 24 and the raster has an extra byte added to each pixel, at the tail end. The value of that byte has the same meaning as in a PAM image with maxval 255.
Each color in the color map is 3 bytes, 8 bits each of red, green, and blue, unless the input is black and white or grayscale, in which case each color in the palette is represented by one byte.
Input must contain no more than 256 distinct colors and must not contain transparency information.
(The transparency limitation is not a limitation of the format, but of pamtotga. Implementing a color map that contains transparency information is harder to implement).
Restrictions are the same as for -cmap.
This option was new in Netpbm 10.85 (December 2018).
You may specify at most one of -mono, -cmap, and -rgb. If you specify neither, the default image type is the most highly constrained compatible type is used, where monochrome is more constrained than colormapped which is in turn more constrained than unmapped.
By default, pamtotga uses the input file name argument, up to the first period (or the whole thing if there is no period). It truncates it as necessary to meet TGA standards. If you specify (or default to) Standard Input, pamtotga omits the image ID from the TGA header.
This program was called ppmtotga until Netpbm 10.6 (July 2002). That was always a misnomer, though, because a PPM class program would not be able to tell the difference between PGM and PPM input (it would all look like PPM), and thus could not choose the output Targa image type based on the type of the input. Netpbm 10.6 also added the ability to handle a transparency channel, so it became a PAM class program.
In Netpbm 10.15 (April 2003), the program became the first in the Netpbm package to recognize a transparency channel in a PAM. It recognized tuple type "RGBA". But when this kind of PAM image was later added to the PAM specification, it was specified with tuple type "RGB_ALPHA". So in Netpbm 10.26 (January 2005), pamtotga changed to recognize "RGB_ALPHA" instead of "RGBA".