In AquaMail it's also driven by image sizes, original vs. size "buckets" (max. 2048 / 1280 / 768)...
...but the dialog gives you size *estimates* so you can decide.
I agree with the idea mikeone (if I understood him correctly), - that was my own reaction as well, but let me rephrase his suggestion.
I'd say that maybe showing explicitly (even if in a smaller font under each option), - the images sizes in pixel,
in addition to the estimated sizes in bytes would be helpful. Maybe those sizes should replace the words "small", "medium", large"?
I.e.
Shrink images
- Do not shrink (17MB)
- 2048x??? ( ~ 2.5 MB)
- 1280x768 (~ 0.99MB)
- 800x600 ( ~ 364KB)
or
Shrink images
- Do not shrink (17MB)
- Large, 2048x??? ( ~ 2.5 MB)
- Medium, 1280x768 (~ 0.99MB)
- Small, 800x600 ( ~ 364KB)
I remember your arguments that not mentioning those explicitly helps to be able to change them later. But when I am sending my images (resizing with QuickPic), - I am choosing the options based on (1) the intent (e.g. to be able to see the detail "A", but just on the desktop monitor -> 1280x768/1024x768) and on (2) my connectivity (e.g. I am in Argentina with extremely limited and expensive traffic allowance, but just need to pass the overall view of an item ASAP -> 800x600 or 640x400). So, knowing the size in pixels helps (1), knowing the estimates size somewhat helps (2).
But I haven't seen the -6 build yet, so, maybe you've already implemented that...
Oh and by the way, "large" is really the only one anybody would need --
1 - big size reduction relative to typical camera rez (8, 12, 16 Mpx)
2 - still large enough even for FullHD displays / TVs
But the "medium" and "small" will stay just in case...
Great! The smaller ones can be handy for the reason (2) above.
PS. And I like the implementation of this feature, - so it is growing on me. My previous doubts of how much I'd use it myself are melting: in some situations, especially for very quick mailing, it will be more convenient than to use QuickPic.
However, if possible, please still keep QuickPic option available: it allows cropping the image in addition to resizing.