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Reading this thread drives me crazy. GAF,
PLEASE learn the difference between
upscaling and
rendering at a higher resolution. Here, I will help you:
Upscaling means taking an existing image (a 2D plane of pixels) and resampling this data to create a higher resolution image. There are many different ways to do this -- often not quite correctly called filters -- like bilinear, bicubic, lanczos or special-purpose algorithms like HQ2X. There are (usually rather small) differences in quality between these algorithms, but they
can never add new data to the image. This is what a fixed resolution display does when supplied a signal different from its native resolution. This is what sub-HD games do on 360 & PS3.
Rendering at a higher resolution means taking the same source data (polygons, shaders, lights, textures etc) and rendering it to a buffer at a higher resolution than before. This increases the amount of information about the spatial structure of the scene (thereby increasing the quality of the final image) and can not be done starting from only image data. So it's impossible to have an external box or TV do this. This is what happens when you change the resolution of a PC game. This is what many emulators can do. (Note that emulators also have other ways of improving the image quality of the original game, like better texture filtering, adding AA or enabling vsync)
Here is a picture to illustrate this:
From left to right: original, simple upsampling, bicubic upscaling, "rendering" at a higher resolution.