Thanks a lot, both of you. Let me ask you for some more advice please.
(Free is kind of the key word here. I suspect that this may be the only map I do, at least for many years. Plus that it kind of rough right now.)
In short: I want 700x700 pixels asc or bmp or geotiff to become 8192x8192 pixels bmp or raw. And smoothed out.
I have already been able to try it out, without editor, and it works, except that I have not been able to smooth it out and thus I get a lot of errors.
I have an app (MICRODEM) that can convert the .asc to GeoTiff or BMP, so that makes me more flexible.
The cropped .asc, saved as a BMP from MICRODEM is about 700x700 pixels.
The converter (TESAnnwyn) I am going to use to convert to the final format accepts either BMP (Exact x/y size) or RAW (any x/y size, stretchable).
The final map is going to be 8192x8192, so I need to smooth things out. And it can be really smooth; it is just supposed to be hills, but with highest point about 250 meters on 14000x14000 meters.
I was thinking that I should go into an editor/generator that can smooth out/or generate a new surface and export this at 8192 pixels bmp, or a raw as high as possible.
Am I way off? Can I get a smooth map (by editing) out of scaling that much?
Edit: I am trying Wilbur right now, and looks good, except that it keeps crashing before I can get my file done.