Problem: editing PNG files misaligns them

[GrayFace]

I'm trying to fix a weapon from Project Brutality, but it gets misaligned.
Original file: https://www.dropbox.com/s/3x7p3meq1thhh ... 0.png?dl=1
Same file opened and saved bu GIMP: https://www.dropbox.com/s/z55dcwpaddep5 ... 0.png?dl=1
They look the same in any viewer, but in game the edited one is misaligned.
When viewing metadata with "ImageMagick\identify.exe -verbose" I see difference in "minimum-bounding-box" values, but no tool that's supposed to copy metadata between images seems to copy these values.

[GrayFace]

I see SetPNG and grabpng can be used to set it, but the only way to get these values I see is through grabpng GUI, while I need a command line tool to extract them from original files and then apply to modified files after each edit...

[Graf Zahl]

If you need a GUI for setting sprite offsets, the best recommendation is SLADE.
General image tools do not know about the Doom specific offset.

[GrayFace]

Graf Zahl wrote:
> If you need a GUI for setting sprite offsets, the best recommendation is
> SLADE.
> General image tools do not know about the Doom specific offset.

I needed the exact opposite. In order to quickly reapply grAB to image you need a .bat file, not GUI. I needed a program that would create such .bat files by extracting grAB information.
I actually created it and now I'm thinking of best interface for it:
Now I'm creating a grAB.bat that sets coordinates for all images in a folder (those that have them set up) and placing it into that folder. Problem is, then these BAT files would probably end up in PK3 archives. Plus, there are many mods with extension-less images, so should I pick them up by default or only *.png by default?