Image quality goes down when creating CC paintings/posters

[catghoti]

I am trying to create custom paintings. I have some really good quality pictures I would like to put in the game(something like 5300x7000, or 1952x2880). However when I size them down and insert them into frames, they become blurry. 

I did my research online and most of them says it's inevitable and you will just have to accept it. Later when I was playing around sims 4 studio I accidently import the original photos onto the texture and turns out the quality remained perfectly. However this way it ruins the frames..... and I can't really adjust image position this way....

 

Is there any solution to this? Please help.