How to combine multiple PNGs into one big PNG file?

Question

I have approx. 6000 PNG files (256*256 pixels) and want to combine them into a big PNG holding all of them programmatically.

What\'s the best/fastest way to do that?

Answer 1

simple python script for joining tiles into one big image:

import Image

TILESIZE = 256
ZOOM = 15
def merge_images( xmin, xmax, ymin, ymax, output) :
    out = Image.new( 'RGB', ((xmax-xmin+1) * TILESIZE, (ymax-ymin+1) * TILESIZE) ) 

    imx = 0;
    for x in range(xmin, xmax+1) :
        imy = 0
        for y in range(ymin, ymax+1) :
            tile = Image.open( "%s_%s_%s.png" % (ZOOM, x, y) )
            out.paste( tile, (imx, imy) )
            imy += TILESIZE
        imx += TILESIZE

    out.save( output )

run:

merge_images(18188, 18207, 11097, 11111, "output.png")

works for files named like %ZOOM_%XCORD_%YCORD.png , for example 15_18188_11097.png