Three sorts of limitations apply:
1) Size: images on the front page are limited to a total width of 505 pixels and should not be taller than about half of that. Images inside a story should not be wider than 800 pixels and no taller than 600. This is to preserve the accessibility of the site for people using smaller monitors. Even those sizes are too large for mobil devices but in the future we will have software in place to shrink or block images that are too big for phones or tablets.
2) File Size: Teaser Images (Images at the top of stories and Title Pages) should not be larger than 50k unless a high level of detail is needed. Images larger than 100k will likely be reduced by our volunteers. We currently consider 30k-75k to be the "sweet spot", this is due to the fact that not everyone has a high speed broadband internet connection. Some of our users still use dial-up, low speed satellite and some are just visiting us over slower transcontinental interconnect links. PLEASE be polite to your readers and take this into account. Images inside a story can be as large as 400k without prior approval, but PLEASE take in to account download times for slower users when making such decisions.
3) Using copyrighted images that belong to someone else is a copyright violation and can get the images taken down if someone complains. I don't police this, I just react to complaints. And there are fair use considerations, if the image is altered enough to be considered a new work but I have to err on the side of the complainant in the case of possible copyright infringement.
4) I don't consider the use of X and XXX rated art or photographs to be appropriate to the mission of this site. Nudity, even nudes in loving embrace, is no more than R or A rating but intercourse complete with fluids and genitalia is definite XXX stuff. It doesn't belong here, plenty of other sites for that kind of thing. Even worse if it is photographs and triple worse if any of the participants even appear to be underage. Don't go there. Since our servers are in the US we are under the most liberal of obscenity laws as long as things are just text. Add images and people visiting the site in some states and in many other places outside the US could get into trouble.
Too many violations of these limitations will force me to restrict access to using images in stories, blogs, etc. to people who prove that they can do so responsibly. And please, don't even upload such images to your folders, even if you are not using them in posts. BC is a story site and stories come first.
Hugs to all,