About Pixillation

In computer graphics , pixelation (or pixellation in UK English) is an effect caused by displaying a bitmap or a section of a bitmap at such a large size that individual pixels, small single-colored square display elements that comprise the bitmap, are visible to the eye.

Early graphical applications such as video ran at very low resolutions (  Image resolution describes the detail an image holds with a small number of colors) and so had easily visible pixels. The resulting sharp edges gave curved objects and diagonal lines an unnatural appearance. However, when the number of available colors increased to 256, it was possible to gainfully employ antialiasing  to smooth the appearance of low-resolution objects, not eliminating pixelation but making it less jarring to the eye. Higher resolutions would soon make this type of pixelation all but invisible on the screen, but pixelation is still visible if a low-resolution image is printed on paper.

So while taking pictures of art works, it is important to take high resolution pictures so that they would be very clear to the eye when prints are taken.