pamcut

Updated: 03 August 2000
Table Of Contents

NAME

pamcut - cut a rectangle out of a PAM, PBM, PGM, or PPM image

SYNOPSIS

pamcut [-left leftcol] [-right rightcol] [-top toprow] [-bottom bottomrow] [-width width] [-height height] [-pad] [-verbose] [left top width height] [pnmfile]

Minimum unique abbreviation of option is acceptable. You may use double hypens instead of single hyphen to denote options. You may use white space in place of the equals sign to separate an option name from its value.

DESCRIPTION

pamcut reads a PAM, PBM, PGM, or PPM image as input and extracts the specified rectangle, and produces the same kind of image as output.

There are two ways to specify the rectangle to cut: arguments and options. Options are easier to remember and read, more expressive, and allow you to use defaults. Arguments were the only way available before July 2000.

If you use both options and arguments, the two specifications get mixed in an unspecified way.

To use options, just code any mixture of the -left, -right, -top, -bottom, -width, and -height options. What you don't specify defaults. It is an error to overspecify, i.e. to specify all three of -left, -right, and -width or -top, -bottom, and -height.

To use arguments, specify all four of the left, top, width, and height arguments. left and top have the same effect as specifying them as the argument of a -left or -top option, respectively. width and height have the same effect as specifying them as the argument of a -width or -height option, respectively, where they are positive. Where they are not positive, they have the same effect as specifying one less than the value as the argument to a -right or -bottom option, respectively. (E.g. width = 0 makes the cut go all the way to the right edge). Before July 2000, negative numbers were not allowed for width and height.

Input is from Standard Input if you don't specify the input file pnmfile.

Output is to Standard Output.

If you are splitting a single image into multiple same-size images, pamdice is faster than running pamcut multiple times.

OPTIONS

-left: The column number of the leftmost column to be in the output. If a nonnegative number, it refers to columns numbered from 0 at the left, increasing to the right. If negative, it refers to columns numbered -1 at the right, decreasing to the left.
-right: The column number of the rightmost column to be in the output, numbered the same as for -left.
-top: The row number of the topmost row to be in the output. If a nonnegative number it refers to rows numbered from 0 at the top, increasing downward. If negative, it refers to columns numbered -1 at the bottom, decreasing upward.
-bottom: The row number of the bottom-most row to be in the output, numbered the same as for -top.
-width: The number of columns to be in the output. Must be positive.
-height: The number of rows to be in the output. Must be positive.
-pad: If the rectangle you specify is not entirely within the input image, pamcut fails unless you also specify -pad. In that case, it pads the output with black up to the edges you specify. You can use this option if you need to have an image of certain dimensions and have an image of arbitrary dimensions.
pnmpad also adds borders to an image, but you specify their width directly.
-verbose: Print information about the processing to Standard Error.

HISTORY

pamcut was derived from pnmcut in Netpbm 9.20 (May 2001). It was the first Netpbm program adapted to the new PAM format and programming library.

The predecessor pnmcut was one of the oldest tools in the Netpbm package.