pngtopam

Convert PNG images to PAM format

TLDR

Convert PNG to PAM

$ pngtopam [input.png] > [output.pam]

Convert with alpha channel

$ pngtopam -alpha [input.png] > [output.pam]

pngtopam converts a PNG image to a PAM (Portable Arbitrary Map) image. Part of the Netpbm toolkit, it preserves transparency when -alphapam is specified. If the input has no transparency, the output is typically an RGB or grayscale PAM.

PARAMETERS

-alphapam

Output a PAM with tuple type depending on the PNG (supports transparency).

-alpha

Extract only the alpha channel as a PGM-style PAM.

-mix

Composite the image against a background color when transparency is present.

-background color

Specify the background color used with -mix (e.g., "rgb:FF/FF/FF" or a color name).

-gamma value

Set the gamma value used for display correction.

-text

Emit any tEXt chunks from the PNG to stderr.

-verbose

Print information about the conversion to stderr.

INSTALL

sudo apt install netpbm

sudo dnf install netpbm

sudo pacman -S netpbm

sudo apk add netpbm

sudo zypper install netpbm

brew install netpbm

nix profile install nixpkgs#netpbm

CAVEATS

Reads from standard input if no file is given. Without -alphapam or -alpha, transparency information may be lost. Replaces older pngtopnm for images needing alpha channel support.

HISTORY

Part of the Netpbm package, which descends from Jef Poskanzer's pbmplus from the late 1980s. PAM was introduced in Netpbm 10.x to unify PBM/PGM/PPM/PAM handling.