My images all have lines/bars running through them. Is it the ink or printer? Can I adjust some settings somewhere? I have an Epson NX100 printer.

I would think it is the ink .. I don't have an edible printer, but with my regular one if I am running low on ink or I have not printed in awhile, ( i guess ink dries a bit) I get lines running through it. HTH

I don't know about the Epson but I have a Canon and had this problem. On mine if you look right where the picture comes out there are little rollers with pins and they collect the ink after a while leaving little white lines(dots) running through mostly dark colored pictures. I'm not sure if this is your problem or not but I can tell you how to fix this problem. Take a stiff paper or the back from frosting sheet and tape paper towel to it. If you have cleaner for your edible image printer you can put some of that solution on the wheels and/or the paper towel and feed it up into the printer moving it back and forth to clean the ink off of it. You can also scrub with a toothbrush. I hope that's not too confusing because it was for me at first before knowing how to clean it.
HTH

I don't think it needs to be clean, I've only printed two sheets so far. The first one did it.

Where do you buy your paper from? Maybe you can call them for technical support. I buy mine from Icing Images and they are a great help and will sometimes offer free frosting sheets if you had a problem

I agree with Kerry_Kake. I use Icing Images for my supplies, they are great. When they sent my ink, they also sent instructions on how to set the printer to get the best results. Most of the time printer software has a place where you can set profiles or save custom settings. You may have to adjust your printer for the icing paper. Give your supplier a call, they can probably give you some insight.

I had the same problem with my first printing, before I remembered to change the print settings to 'photo' and 'matte paper.'

I also have this problem....more when I enlarge a photo too big. I just try not to over enlarge anything and that seems to help.

Theres a couple of different reasons for this, first and foremost are the lines horizontal or vertical? Vertical lines means you have a build up on the rollers, there are a couple of different methods of resolving this. There hopefully is a maintenance setting where it offers roller cleaning or bottom plate cleaning, if it has these options then use both using card stock or a heavy weight paper. If not try changing the printing preferences to envelope setting instead of plain paper. (this increases the gap between the rollers, so it doesnt grab as tight) The other option is more tedious but it is a true solution is to get something small thin and sturdy, a flashlight and look where the paper exits, you will find tiny small rollers and those can be cleaned off reducing the amount of build up on the rollers.
If your printer has a bottom cassette tray you can use it instead of feeding your icing sheet from the top, just remember to place it face down. I usually use the bottom tray for prints that are black, dark blue or have a darker color to them because there is a different set of rollers used, and if you have a good quality icing sheet it will make the 180 turn with no problem. I save the top feed for my lighter color icing sheets.
Hope these tips help out some.