bash: create black rectangles / squares using imagemagick

To create rectangles of a solid color with bash, following script comes in handy. Save it in a file, e.g. createBlackRect.sh and run it with

bash /path/to/script/createBlackRect.sh

Here the script

#!/bin/bash

# ============================================================================================
# creates several black square .png images
# ============================================================================================

for (( i=128; ${i}<=800; i++));  do
    for ((j=128; ${j}<=800; j++)); do
        convert -size ${i}x${j} xc:#000000 BlackSquare_${i}x${j}.png
    done
    echo Created File ${i} of 800
done

#000000 is the color black, to have another color, e.g. red use #990000. For more color information, see imagemagick color names.