Ah thats probably the reason why my s4 screen looks ghastly. Basic LCD screen technology as the cheap substitute to the original proper AMOLED screens of Samsung. There was a SAMSUNG retailer shop that you can send in your Samsung device if you have a serious issue. I asked there if they could replace the screen and they said they be able to do it for 100 quid. I was like NO WAY I"M not paying that amount of money, so I went to this iRepair shop said they would do it for 85 quid and they added me a screen guard for 5 quid so in total 90 quid. I was like oh heck this is probably as cheap as it gets so I went for it.
Also the s4 screen digitiser has got fluctuations in terms of response to touch sensitivity but overall it is OK. I am just hoping that I can get another 2 years out of my s4 because I really love it and I just like all my messages and photos of my friends and so on
and now I can use WhatsApp, Viber, SMS and Snapchat as well as Gmail, FaceBook and so on
What I love about Samsung phones is of their excellent quality cameras, my s4 one still does the great job for a smartphone
plus for example the S8 phone still offers the good old headphone jack so you can plug in your favourite existing earphones
and I must say it looks much more swankier than the ipHone X so no need to buy a wireless headphone set. Plus I received a new pair of earphones for this year xmas