Media file formats As an example, in
PCM sound
encoding the first bit in the sample denotes the sign of the function, or in other words defines the half of the whole
amplitude values range, and the last bit defines the precise value. Replacement of more significant bits result in more distortion than replacement of less significant bits. In lossy
media compression that uses bit-planes it gives more freedom to encode less significant bit-planes and it is more critical to preserve the more significant ones. As illustrated in the image above, the early bitplanes, particularly the first, may have constant runs of bits, and thus can be efficiently encoded by
run-length encoding. This is done (in the transform domain) in the
Progressive Graphics File image format, for instance.
Bitmap displays Some computers displayed graphics in
bit-plane format, most notably PC with
EGA graphics card, the
Amiga and
Atari ST, contrasting with the more common
packed format. This allowed certain classes of image manipulation to be performed using bitwise operations (especially by a
blitter chip), and parallax scrolling effects.
Video motion estimation Some
motion estimation algorithms can be performed using bit planes (e.g. after the application of a filter to turn salient edge features into binary values). This can sometimes provide a good enough approximation for correlation operations with minimal computational cost. This relies on an observation that the spatial information is more significant than the actual values. Convolutions may be reduced to
bit shift and
popcount operations, or performed in dedicated hardware.
Neural networks Bitplane formats may be used for passing images to
Spiking neural networks, or low precision approximations to
neural networks/
convolutional neural networks. == Programs ==