Update - I was a bit too quick to post triumphant news, seems Photoshop pulled a fast one on me and let me gaze, for some strange reason, on an uncompressed version of the image when I opened the .dds file. Pixelation is still a problem for large textures, and upon educating myself a bit further about the dds image format I suspect there is no easy way around it as the artifacts and errors happen because of the inevitable compression. Some sites suggest manual editing of the texture using various techniques to try and combat the appearance of artifacts, but that is simply out of the question for large and detailed images such as this:
Apparently the problem are smooth gradients in the texture. I examined the vanilla backdrops and either IC used some unknown method to preserve the crispness of their images or those images were carefully made so that they do not contain any problematic areas where artifacts may occur. Anyway, I tried to get the kind of backdrops you can see in X3, but it now looks to me like that game uses a different file format for that purpose. What is vital is the preservation of minute details - the above texture is a half-hour work, what I truly had in mind is more akin to this. As you can see from that example, any pixelation or artifacting would quite ruin the effect.
If you examine the vanilla backdrop images, notice how well the details and edges are preserved. This above all else makes me suspect that there is a way to circumvent the effect .dds compression has on high-detail imagery - I am just unable to find it, and its frustrating.
So the invitation to anyone with some experience in this matter to come and help stands.
