Quote:...snip...Would really like it to take up the same, smaller amount of space as other documents I have of the same dimensions.
Well AFAIK you can get ImageMagick (IM) for MacOS and one command is compress to a (roughly) specific file size. Example: Quite a colorful jpeg scaled up in GIMP to your 10800x7200 = about 13 MB jpeg filesize, exported as 90 quality with chroma halved, no thumbnail, no colour profile.
To recompress, The IM command is
Code:
convert a.jpg -define jpeg:extent=2000kb newfile.jpgStill using IM, the identify command, comparing the properties.
Image: a.jpg
Format: JPEG (Joint Photographic Experts Group JFIF format)
Mime type: image/jpeg
Class: DirectClass
Geometry: 10800x7200+0+0
Resolution: 300x300
Compression: JPEG
Quality: 90
Filesize: 12.8521MiB
-------------
Image: newfile.jpg
Format: JPEG (Joint Photographic Experts Group JFIF format)
Mime type: image/jpeg
Class: DirectClass
Geometry: 10800x7200+0+0
Resolution: 300x300
Print size: 36x24
Compression: JPEG
Quality: 10
Filesize: 1882910B
Look at the estimated quality 10. I would be very wary compressing large images too much.