One of my most used paint programs (Ulead Photoimpact - now Corel) has an excellent exporter that calculates the file size as you change settings for jpg, png, gif. Its super useful when I am exporting to attach to an email or when I need to know the data transfer overhead for a webpage (say).
It looks like this (in part):
http://i65.tinypic.com/2zqszkj.jpg
This suggests that its not impossible to calculate the size before saving. Of course this tool is way over the top for what is being suggested. A simple slider for jpg quality would suffice.
On 2/18/2017 6:39 AM, Tobias Ellinghaus wrote:
Am Freitag, 17. Februar 2017, 10:27:32 CET schrieb LucaDC: Guessing the size of the PNG in advance is most likely next to impossible. And given how long a PNG export takes it's not really feasible to do one every time the export dialog is shown just to gather the file size.
Tobias