Quote:...Running GIMP 2.8.10 on Windows 7...
That is an old version, seriously advise updating to the most recent Gimp 2.8.22 see: http://www.gimp.org
edit: This has just sunk in
Quote:....are in the realm of 5000x3864 pixels and 200MB...
My digital camera takes images about that size, jpegs are about 7 to 8 MB, a RAW image 23 MB
Converting to an uncompressed tiff and it is 54 MB.
What exactly is the image format?
-----------
You can try something like this.
1. Crop the image to a square. You can set the aspect ratio to fixed and the ratio to 1:1
screenshot: https://i.imgur.com/znZYM0J.jpg
2. Scale down to 96 x 96 pix, Use Sinc(Lanczos3) for the interpolation
https://i.imgur.com/zfkO4sG.jpg
3. No screenshot for this but try a little sharpen Filters -> Enhance -> Unsharp mask try default values.
4. Export as a jpeg. tick the Show preview in image window box, that will give a size estimate just above. Untick all the unnecessary items - Exif etc. Set the sub-sampling to 4:2:2 Adjust the quality setting to get the file size.
https://i.imgur.com/xLZD5Ub.jpg
And it should not be too bad, it is for an email after all. showing at 300% https://i.imgur.com/5oDxJkj.jpg
How many of these to do? Might be possible to use a batch file, all depends on the position in that first procedure, cropping to a square.