ImageMagick crop huge image

Question

I am trying to create tiles from a huge image say 40000x40000

i found a script on line for imagemagick he crops the tiles. it works fine on small images like say 100

Answer 1

You may try to use gdal_translate utility from GDAL project. Don't get scared off by the "geospatial" in the project name. GDAL is an advanced library for access and processing of raster data from various formats. It is dedicated to geospatial users, but it can be used to process regular images as well, without any problems.

Here is simple script to generate 256x256 pixel tiles from large in.tif file of dimensions 40000x40000 pixels:

#!/bin/bash
width=40000
height=40000
y=0
while [ $y -lt $height ]
do
   x=0
   while [ $x -lt $width ]
   do
      outtif=t_${y}_$x.tif
      gdal_translate -srcwin $x $y 256 256 in.tif $outtif
      let x=$x+256
   done
   let y=$y+256
done

GDAL binaries are available for most Unix-like systems as well as Windows are downloadable.