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1.
In a digital raster image, the pixelation or presence of distorted pixel artifacts generally caused by image compression in lossy file formats.

The name arises from the tendency of this messy dithering effect to appear splattered along the edges of contrasting color areas, as if pixels were vomited upon portions of the image.

Also sometimes referred to as pixel vomit.
The JPEGs Lydia exported were full of pixel barf.

The pixel barf was a clear indicator that this image would not be suitable for print.
by Graphics Victim December 02, 2011