I don't know if the LN-T3242H has Wiselink or capable of viewing JPGs. One way to test, although not perfect, but probably 70% accurate is to put a few nicely contrasted high resolution JPGs on a USB flash drive. Take it to the store plug it in and look at the JPG. See if the Black is to your liking.
For the LN-T4065F I plug it in, go to Wiselink and it detects the USB drive (FAT32 PQI 1GB USB Flash), click it with and it shows JPGs in a slide show. You can even configure background music
Down side is it only allows you to use the default picture modes - Dynamic, Normal and Movie without letting you calibrate the settings. But like I said, not 100% but gives you a fairly good idea to compare with.