Image resolution on a CCD.?

Question

On some camcera's or Camcorders, the image is smeared when the digital zoom is maxed out, why does that happen?

Is it the Pixel count or the horazontal lines resolution that causes that?

Answer 1

Digital zoom is a method of decreasing (narrowing) the apparent angle of view of a digital photographic or video image. Digital zoom is accomplished by cropping an image down to a centered area with the same aspect ratio as the original, and usually also interpolating the result back up to the pixel dimensions of the original. It is accomplished electronically, without any adjustment of the camera's optics, and no optical resolution is gained in the process.

Because interpolation disturbs the original pixel layout of the image, as captured by the camera's image sensor, it is usually considered detrimental to image quality. The results of digital zoom are, however, sometimes superior to the results of manual cropping and resizing (interpolation) in post-production. This is because the camera may apply its interpolation before performing lossy image compression, thereby preserving small details that would otherwise be lost. For cameras that save images in a raw format, however, resizing in post-production will yield results equal or superior to digital zoom.[citation needed]

Some digital cameras rely entirely on digital zoom, lacking a real zoom lens, as on most camera phones. Other cameras do have a real zoom lens, but apply digital zoom automatically once its longest focal length has been reached. Professional cameras generally do not feature digital zoom.