You can even see this problem in the article. The convolution-based sample image is clearly darker than the nearest-neighbour one. People go all crazy about in

You can even see this problem in the article. The convolution-based sample image is clearly darker than the nearest-neighbour one. People go all crazy about interpolation and then get the brightness wrong. It's even more obvious for high resolution photos of a tree or grass in bright sunlight. Once you start looking you notice the change in brightness everywhere, when you click on a thumbnail or while a JPEG is loading.