itch.io

No objections here.

Using cygwin or a unix environment, a bash file with check_images.txt

In short, it will scan png files and see if it's a PNG, and if it isn't then it will tell you what it actually is.

#!/bin/bash
find "$@" -iname "*.png" -print0 | xargs -r -0 file | sed -E "/\.[pP][nN][gG]:\s*PNG/d"
find "$@" -iname "*.jpg" -print0 | xargs -r -0 file | sed -E "/\.[jJ][pP][eE]?[gG]:\s*JPEG/d"
find "$@" -iname "*.jpg2" -print0 | xargs -r -0 file | sed -E "/\.[jJ][pP][eE]?[gG]:\s*JPEG/d"
find "$@" -iname "*.bmp" -print0 | xargs -r -0 file | sed -E "/\.[bB][mM][pP]:\s*PC bitmap/d"

While appending the real extensions (and being able to undo them, i use work/unwork as scripts)

#!/bin/bash
T=`check_images.txt "$@"`
echo "$T" | grep "JPEG image data" | sed -E -e "s:':'\"'\"':g;s/:.*//;s/(.*)/mv '\1' '\1.jpg'/" >work
echo "$T" | grep "PNG image data" | sed -E -e "s:':'\"'\"':g;s/:.*//;s/(.*)/mv '\1' '\1.png'/" >>work
echo "$T" | grep "Web/P image" | sed -E -e "s:':'\"'\"':g;s/:.*//;s/(.*)/mv '\1' '\1.webp'/" >>work
echo "$T" | grep "GIF image data" | sed -E -e "s:':'\"'\"':g;s/:.*//;s/(.*)/mv '\1' '\1.gif'/" >>work
echo "$T" | grep "JPEG image data" | sed -E -e "s:':'\"'\"':g;s/:.*//;s/(.*)/mv '\1.jpg' '\1'/" >unwork
echo "$T" | grep "PNG image data" | sed -E -e "s:':'\"'\"':g;s/:.*//;s/(.*)/mv '\1.png' '\1'/" >>unwork
echo "$T" | grep "Web/P image" | sed -E -e "s:':'\"'\"':g;s/:.*//;s/(.*)/mv '\1.webp' '\1'/" >>unwork
echo "$T" | grep "GIF image data" | sed -E -e "s:':'\"'\"':g;s/:.*//;s/(.*)/mv '\1.gif' '\1'/" >>unwork