any digital image would be pixeled, jpg, bmp, gif,
only through printing does the pixel become replaced with dots of color or ink,
if image is low quality, around 2 megapixels,
you could try increasing size ratio 200% or more,
and resample, and add ppi if low at 72, double to 144 ppi,
also if you have printer and scanner, you could print out full size, then scan at 300 /600 dpi, then re-edit as new image with smaller pixels per inch ratio,
the image you have now you can try to diffuse or denoise, sharpen, anisotropic filtering
and adjust rgb levels,
BenVista Photozoom Pro
SeasideSoft Photo Resizer
STOIK Smart Resizer
ClearID - Photoshop Forensic Plugins
Focusmagic Sharpen Your Blurred
There isn't any.
You can try the "Smart Blur" in Photoshop filters.
if a pic is PIXELATED, it is cos it is low-res/low-quality...
you can't improve on a low-quality result... you need to hop the original is high quality and use that...
If it's just B&W like clipart, you can do it by putting the B&W work on a transparent layer and blurring the edges with the distort filter, there is an online tutorial. That works for fonts, too.
But if it is a colored image, there is nothing you can do, without extensive hand work, becuase you are missing data, which is why it's pixelated.
The same way you unscramble an egg.