Change picture data only, keep all other file data untouched - how?

[reddydust]

Change picture data only, keep all other file data untouched - how?
GraphicConverter 9, Mac

Hello. I've got a very specific problem.

Question:
How can GC change picture data only while keeping the original file format and any non picture data untouched?

File source: Windows Game
Appearance on Mac: Unix exec, no suffix
GraphicConverter info: jpg file

Job:
Transfer file from Windows to Mac
Alter picture data
Save file
Transfer file from Mac to Windows
Replace original file with altered file
Open file ingame

Current problem:
Altered file is not recognized ingame

Thanks for any suggestions

[forum_adm]

Hi,

a JPEG file does not have to be converted for the Mac.
It just needs the correct extension JPG or JPEG and the macOS will support it.

Thorsten

[reddydust]

Thanks for your reply.

I did not say that I want to convert the file.

The job is:
1. to open the original file.
2. to alter the picture data.
3. to save the file without changing any "non picture data."
Is GC able to do point 3.?

I have to assume that GC changes unknown internal file data during the save process.
Why? Because the original application doesn't recognize the altered file.

I hope I have made myself clearer.

[forum_adm]

Yes, just select in the JPEG options (save as) to save with the Original Exif.

[reddydust]

It doesn't work.

Even re-saving the file without any changes result in being not recognized.
So I have to assume there are differences in some kind of file data between both versions.

If you are interested, i can provide you with the original file.

Thanks for your efforts.

[forum_adm]

Please email your file zipped to support@lemkesoft.de