There is software for forums that resizes images
SMF does not have admin options that automatically change the image size of the photo. The software is currently set to recode the image, reduce the quality of the image a bit to remove embedded malware but the length and width of the image stays the same. A recoded 3,000 by 2,000 image will have a smaller file size but the recoded image will still be 3,000 by 2,000. The dpi is changed a bit in the recoding if you look at the meta data of any uploaded image.
Microsoft Paint is one quick way to resize a large image, what I used to get the above images to load. Takes but a few seconds. There are other image editing programs provided by browser platforms or available as free downloads on the forum.
I have a Photoshop Elements FREE app on my iPhone that allows me to rotate and/or crop images. Cropping an original image to just the image, getting rid of the background clutter, is usually enough to produce an image that can be uploaded.
There is an admin option to reject any image that is over a certain file size but members on the forum, a few months ago, felt it was better to let the individual member edit their own images before uploading them so the images are of the content and quality they want and not selected by a software program. We did limit the file size for a few days and found that drew more complaints that the one or so a month member who forgot a large image will crash the RAM server memory and produce a blank/white screen.
We then took the size limit off. It can be put back on but we prefer members to take personal responsibility of their images. Recoding got rid of the security error flag due to suspicious code in the meta data but in solving that problem, the blank screen appeared due to the server running out of memory when recoding large (greater than 2,500 to 3,000 largest side) images. Upload size limit would keep that from happening but then large pdf files could not be attached.
There is an option that allows the admin to set the size of the image as it displays on the forum. This is currently set to 1,000 pixels. Images that are larger than than are converted to a png thumbnail and the thumbnail displayed. Clicking on the displayed thumbnail will open up the full image in a new window, expanding the image to the full size, as uploaded.
Lot of moving parts when it comes to images. We just can't make everyone happy all of the time now, can we? At least no one has complained about getting a security error flag for more than half a year now.
I would think, and this is my very personal opinion as a member and not a moderator, that anyone who feels a particular image is worth posting on the forum for the world to see would also take the time to do whatever is necessary to post the image well -- rotated correctly, cropped, resized to meet software parameters so it will upload. Taking short cuts, posting directly from a snap shot taken by a smartphone with a 12 megapixel camera, just won't work. And that is a well known and easily resolved issue.