It's up to you, but why would you want to post lower quality images of a much greater filesize? - the worst of all possible worlds.
hi,
I will explain the method I use, perhaps this put this difference of opinion into context.
I use a freeware program called 'Screenhunter' to grab a rectangular area of the screen of the drawing I am creating or from say a datasheet etc.
This can either save as bmp or jpg, I choose the jpg format as its much smaller than the bmp.
I can immediately post this jpg to the forum, it saves to extra steps in using 'PrnScn', where I have to open my paint shop pro, open a new drawing, paste in the capture, crop and resave as a clip.
I fully appreciate what you are saying about creating an original drawing and saving as png, being smaller than the jpg that would be generated if i used png thoughout.
As a example I have used your 'logo', no offence intended.
If you look at images and screenhunter1.jpg showing the relative sizes of a captured image, you can see that the captured jpg is a third of the size of the png capture.
Thats why I choose to post in the jpg format.
When I do a detailed circuit drawing, using expresssch, which saves in bmp, I then use Open Office to convert to pdf, so you see I do take time and trouble when I see the need for a good quality drawing.
But for a simple explanation type drawing, I do believe a low quality jpg gets the job done.