(04-07-2017, 08:12 PM)vakita Wrote: I'm still a little confused but, if I understand correctly, if I want to continue to make changes to an image at a later time, I should save them as an xcf file.
Yes.
(04-07-2017, 08:12 PM)vakita Wrote: Also a jpg will loose some quality each time it is exported, so in order to avoid that I should use png.
No. If you have a "perfect" image (XCF, PNG, TIFF) and export it to JPG multiple times, you get a loss but it's the same loss every time from the initial perfect image. The problem of cumulative loss arises when you export to JPG, then reload the JPG to edit it and re-export to JPG (typically what many people do with JPG from their camera). And even then, the loss is not as important as what most people think. If the file is saved back with the same settings (and by the same code) the same encoding is produced for 8x8 blocks with unchanged pixels. So after an initial loss due to the first compression, further loss will happen only around changed pixels. In other words, as long as you do "local" editing you don't lose much. But changing quality settings or doing some global change (constrast, luminosity, etc...) will entail a new loss (although likely less than the initial one).
(04-07-2017, 08:12 PM)vakita Wrote: If I am finished making changes to an image that I want use on a website would you recommend that I export it as a jpg as opposed to png for the advantage of the much smaller size ?
It depends a lot on the image... For photo JPEG is usually somewhat smaller. For computer graphics (logos, text) PNG is smaller, and in any case the sharp edges and high contrast of these pictures make the compression artifacts of JPG very visible, so JPG is best avoided... But under 100K size is nothing to worry about, most web pages are over severam megabytes these days, due to all the javascript.