Hi everyone!
I need help from the GC community, especially those who are familiar with TinyScheme scripting language.
A couple years back I read this blog by Dr Neal Kravetz http://www.hackerfactor.com/blog/index. ... toria.html
and a few of his other articles on digital image forensics. I found a GIMP script by elsamuko called Error Level Analysis https://sites.google.com/site/elsamuko/forensics/ela
I only used it a few times with GIMP 2.6 and completely forgot about it until yesterday. The script is still there but it's not working with GIMP 2.8.x

The script creates a temporary jpeg file from the original with different compression level and then compares the difference in error levels to indicate possible
modifications to the original image.
Any attempt to execute the script returns Error: ( : 1) Procedure execution of file-jpeg-save failed: Could not open 'error-level-analysis-tmp.jpg' for writing: Permission denied
Can anyone, please, tell me what is it that prevents this script from working? Thank you in advance!

P.S. If you read the blog^, do you think it's possible to write a script or scripts that would do other kinds of analysis mentioned there,
e.g. demosaic modification analysis, min/max measurements of image noise levels. And is it possible to create Luminance gradient of the image in GIMP?
Thanks again.
K1TE

P.P.S. If someone's interested, there's more about ELA here http://fotoforensics.com/tutorial-ela.php

Just include a valid path before the filename eg: see below

OK, that worked!!!
Thank you b10h4z4rd!