BWCROP(1)

NAME

bwcrop - crop black and white bw files

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SYNOPSIS
DESCRIPTION
ARGUMENTS
EXAMPLES
SEE ALSO
AUTHOR
COPYRIGHT
BUG REPORTS

SYNOPSIS

bwcrop in.bw out.bw

bwcrop in.bw out.bw inwidth outwidth outheight ulx uly urx ury lrx lry llx lly

DESCRIPTION

bwcrop extracts a quadrilateral region from an arbitrarily large bw(5) input file (in.bw), maps that region to a specified output image size, and writes the result to out.bw.

If only the input and output files are provided, bwcrop will prompt the user interactively for the remaining parameters. All responses should be pixel counts or first-quadrant coordinates.

Alternatively, all parameters can be provided on the command line for use in scripts. The coordinate names refer to the input file, in clockwise order starting from the upper-left corner. The nearest input pixel is selected for each output pixel; no interpolation is performed.

If an output dimension is one pixel, bwcrop samples the midpoint of the quadrilateral along that axis.

ARGUMENTS

inwidth: Width of the input image (scanline length).
outwidth, outheight: Dimensions of the output image.
ulx, uly, urx, ury, lrx, lry, llx, lly: Coordinates defining the quadrilateral in the input image to be cropped. These correspond to the upper-left (ulx, uly), upper-right (urx, ury), lower-right (lrx, lry), and lower-left (llx, lly) corners, respectively.

EXAMPLES

Example 1. Cropping a tilted region from a 512x512 image into a 100x100 image

$ bwcrop input.bw output.bw 512 100 100 256 512 512 256 256 0 0 256

This command extracts the diamond-shaped region bounded by (256, 512), (512, 256), (256, 0), and (0, 256) from the 512x512 input.bw image, and outputs it as a 100x100 rectangular image in output.bw.