pamscale
resizes PAM/PNM images using high-quality resampling
TLDR
Scale to specific size
$ pamscale -width [800] -height [600] [input.pam] > [output.pam]
Scale by factor$ pamscale [0.5] [input.pam] > [half.pam]
Scale preserving aspect ratio$ pamscale -xyfit [800] [600] [input.pam] > [output.pam]
Scale width only$ pamscale -xsize [800] [input.pam] > [output.pam]
High quality scaling$ pamscale -filter=lanczos [0.5] [input.pam] > [output.pam]
SYNOPSIS
pamscale [options] [scale] [pamfile]
DESCRIPTION
pamscale resizes PAM/PNM images using high-quality resampling. It can scale by factor, to specific dimensions, or fit within a bounding box while preserving aspect ratio.
PARAMETERS
scale
Scale factor (0.5 = half).-width, -xsize n
Output width.-height, -ysize n
Output height.-xyfit w h
Fit within box, keep aspect.-filter name
Resampling filter.-linear
Linear interpolation.
FILTERS
$ point - Nearest neighbor
box - Box filter
triangle - Linear/bilinear
lanczos - High quality (default)
box - Box filter
triangle - Linear/bilinear
lanczos - High quality (default)
CAVEATS
Upscaling may blur. Very small scales may lose detail. Large images need memory.
HISTORY
pamscale is part of Netpbm, providing high-quality image scaling with various resampling algorithms.
SEE ALSO
pamenlarge(1), pamstretch(1), pnmscale(1)