PIXMORPH(1)

NAME

pixmorph - feature-based morph between two pix(5) images

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SYNOPSIS
DESCRIPTION
OPTIONS
EXAMPLES
SEE ALSO
AUTHOR
COPYRIGHT
BUG REPORTS

SYNOPSIS

pixmorph [-w _width_] [-n _height_] _picA.pix_ _picB.pix_ _linesfile_ _warpfrac_ _dissolvefrac_ > _out.pix_

pixmorph performs feature-based image metamorphosis between two pix(5) images, picA.pix and picB.pix, writing the resulting image to standard output. The two images must have the same dimensions; the size is taken from picA.pix automatically unless overridden with -w and/or -n.

The morph is controlled by linesfile, which holds pairs of directed line segments that match corresponding features in the two images (for example, a segment along the nose in picA.pix paired with the corresponding segment in picB.pix). Such a file can be produced with a utility such as morphedit.tcl.

Two scalars in the range [0, 1] drive the result. warpfrac controls how far the features of each image are warped toward the other; dissolvefrac controls how much cross-dissolve is blended between the two warped images. Typically the user sets warpfrac = dissolvefrac, and produces a morph animation as a sequence of frames with steadily increasing values.

The linesfile begins with header constants a, b, p, and the line count n, followed by n segment pairs (each segment is four reals in unit-square coordinates). The constants weight each segment’s influence by length ^p) / (a + dist ^b; in practice a = 0.1, b = 2.0, p = 0.2 work well. For a full description of the algorithm see T. Beier and S. Neely, "Feature-Based Image Metamorphosis", SIGGRAPH 1992 Computer Graphics Proceedings (volume 26 number 2), pp 35-42.

OPTIONS

-w width: Set the width, in pixels, of the input images. Disables autosizing.
-n height: Set the height, in pixels, of the input images. Disables autosizing.

EXAMPLES

Example 1. Generate a six-frame morph animation

for i in 0 1 2 3 4 5; do
    f=$(echo "$i / 5" | bc -l)
    pixmorph face1.pix face2.pix lines.txt $f $f > frame$i.pix
done

Produces a sequence of frames morphing face1.pix into face2.pix. Because warpfrac = dissolvefrac runs from 0.0 to 1.0, frame0.pix equals face1.pix and frame5.pix equals face2.pix, with the intermediate frames blending feature warp and cross-dissolve together.

Example 2. Warp without cross-dissolving

pixmorph face1.pix face2.pix lines.txt 0.5 0.0 > out.pix

With dissolvefrac = 0 the contribution of face2.pix is ignored at the dissolve stage, so out.pix consists entirely of face1.pix warped 50% toward face2.pix according to lines.txt. Conversely, setting warpfrac = 0 yields a plain 50% cross-dissolve with no warping.