best quality pic formatting for the forums? 0

[Timeless icons]

Hello all. 

I always notice that the pics I post, are somewhat blurry in comparison to pics posted by other board members. My pics are usually high resolution (example 1650x2600 resolution) and formatted in .jpg. I pull them up on my 4k monitor and they are razor sharp. I understand that pics likely get capped and compressed when being uploaded but other posters obviously have found a way to do it that allows for better imagery. Normally, I just hit the "choose files..." option and pick the image I want to upload. I've also tried png files with no noticeable difference. Perhaps there's another way to achieve better quality when uploading to the forum? 

Thank you