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if i use a texture in a game with a resolution of 128*128 for a tile which is actually 64*64 on screen and both textures show the same image just in different resolutions. One in 128*128 and one in 64*64. How big are the quality bennefits and is it a good idea to use the texture with the higher resolution even if it will be downscaled anyway?

Thx

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  • \$\begingroup\$ If you dont downscale in runtime you have one powerful card in your hands - graphics editor. If you downscale the texture "offline" manually it gives you better control over its quality and overall appearance, you cannot do that in runtime. \$\endgroup\$
    – wondra
    Sep 13 '14 at 15:09
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When you downscale an image that's when mipmapping kicks in and GPU uses lower resolution version of the texture (assuming the texture is mipmapped). So if you render 128x128 texture in 64x64 pixels on screen GPU is actually using 64x64 image for the rendering due to mipmapping. If you don't use mipmapping though, GPU uses the original 128x128 image, but there are texture aliasing issues which result it worse quality than using texture resolution which closely matches the screen size.

There are different ways to create downscaled versions of the texture as well to improve quality. The standard box filter simply averages 2x2 pixels for every pixel in lower-res mip level. You can have more sophisticated mip generation though by using for example bicubic or sinc filters which better preserve frequencies of the original image.

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