It has probably nothing to do with the image itself (unless you actually have those lines IN your image but I guess you dont) but with the way the texels are rasterized. Clamping only works if the area of the texture that you are drawing is equal to the entire size of the texture. If you are using a texture atlas and only drawing a portion of it clamping will not help. In this case you need to either change the filters to a nearest neighbour filter or add a transparent border around each part of the texture atlas.Ok, let me see I actually understood that as a newbie that I am.
The problem is not from the image but from how openGL is interpreting the image and translating its data into actual pixel to the screen.By using a texture atlas I don´t really know what you mean, but I´d say I´m not. I have 2 methods defined for drawing images, one that allows me to define the actual size I want to draw the image at, and the other one uses the actual image size, but both seem to make the lines appear (btw, I´m trying to keep this royect with a high level of abstraction, so I´m using slick´s resource loader to load the image and whatnot).
So please, could you detail a bit more the infor you just gave me, because didn´t really caught the second part.
Also, I don´t know if this:
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
is setting the filter to nearest neighbor as you sugested, but it still doesn´t work