vector-pixels.txt

Creating a vector image from a raster image usually consists of imagining some kind of curve, responsible for the pixels. But this is guess work at best. Why don’t we work with what’s actually there—points?

This script turns an image into a grid of vector squares, circles, or squares with rounded corners.

usage, on the command line:

python vectorpixel.py inputimage.tiff > outputimage.svg

A limitation is currently that it’s black and white, but that should be easy to change.

#!/usr/bin/env python
""" Generates vectorpixels based on 2-bitmaps (2 color pictures).

    TODO: allow multi-colour pictures, implement vertical and horiontal scanlines """

import Image
import sys

class vectorpixel:
    def __init__(self, image):
        self.i = Image.open(image)
        self.i.convert("1")
        self.px = self.i.load()
        self.constructed = False

    def construct(self, grid=24, line=1, rounded=4, test=(lambda x: x != 0)):
        self.grid = grid
        self.line = line
        self.rounded = rounded
        self.width = self.height = self.grid - 2 * self.line
        self.test = test
        self.fill = '#000000'
        self.constructed = True

    def _yieldlocations(self):
        for x in range(self.i.size[0]):
            for y in range(self.i.size[1]):
                if self.test(self.px[x,y]):
                    yield (x,y)

    def _mkelements(self):
        for l in self._yieldlocations():
            yield "<rect x='%s' y='%s' width='%s' height='%s' rx='%s' fill='%s'/>" % (
    self.grid * l[0] + self.line, self.grid * l[1] + self.line, self.width, self.height, self.rounded, self.fill)

    def _format(self):
        output = '<svg xmlns="http://www.w3.org/2000/svg" width="%s" height="%s">\n' % (self.i.size[0] * self.grid, self.i.size[1] * self.grid)
        for e in self._mkelements():
            output += e
            output += '\n'
        output += '</svg>'
        return output

    def generate(self):
        if not self.constructed:
            self.construct()
        return self._format()

    
if __name__ == "__main__":
    v = vectorpixel(sys.argv[1])
    v.construct()
    print v.count_elements()