This article is about the digital information term. For the company, see Bitplane

Bitplane

Bitplane is a provider of software for 3D and 4D image analysis for the life sciences. Founded in December 1992, Bitplane operates out of two offices in Zürich, Switzerland and one in South Windor, CT, USA.- Company history :...

. For the Bureau of Inverse Technology, see BIT Plane

Natalie Jeremijenko

Natalie Jeremijenko is an artist and engineer whose background includes studies in biochemistry, physics, neuroscience and precision engineering. She is an active member of the net.art movement, and her work primarily explores the interface between society, the environment and technology...

.

A bit plane of a digital

Digital

A digital system is a data technology that uses discrete values. By contrast, non-digital systems use a continuous range of values to represent information...

 discrete signal

Discrete signal

A discrete signal or discrete-time signal is a time series consisting of a sequence of qualities...

 (such as image or sound) is a set of bit

Bit

A bit is the basic unit of information in computing and telecommunications; it is the amount of information stored by a digital device or other physical system that exists in one of two possible distinct states...

s having the same position in the respective binary numbers.

For example, for 16-bit

16-bit

-16-bit architecture:The HP BPC, introduced in 1975, was the world's first 16-bit microprocessor. Prominent 16-bit processors include the PDP-11, Intel 8086, Intel 80286 and the WDC 65C816. The Intel 8088 was program-compatible with the Intel 8086, and was 16-bit in that its registers were 16...

 data representation there are 16 bit-planes: the first bit-plane contains the set of the most significant bit and the 16th contains the least significant bit.

It is possible to see that the first bit-plane gives the roughest but the most critical approximation of values of a medium, and the higher the number of the bit-plane, the less is its contribution to the final stage. Thus, adding a bit-plane gives a better approximation.

Incrementing a bit plane by 1 gives the final result half of a value of a previous bit-plane. If a bit is set to 1, the half value of a previous bit-plane is added, otherwise it does not, defining the final value.

Bitplane is sometimes used as synonymous to Bitmap

Bitmap

In computer graphics, a bitmap or pixmap is a type of memory organization or image file format used to store digital images. The term bitmap comes from the computer programming terminology, meaning just a map of bits, a spatially mapped array of bits. Now, along with pixmap, it commonly refers to...

; however, technically the former refers to the location of the data in memory and the latter to the data itself.

One aspect of using bit-planes is determining whether a bit-plane is random noise or contains significant information.

One method for calculating this is compare each pixel (X,Y) to three adjacent pixels (X-1,Y), (X,Y-1) and (X-1,Y-1). If the pixel is the same as at least two of the three adjacent pixels, it is not noise. A noisy bit-plane will have 49% to 51% pixels that are noise.

Applications

As an example, in PCM sound encoding

Code

A code is a rule for converting a piece of information into another form or representation , not necessarily of the same type....

 the first bit in sample denotes the sign of the function, or in the other words defines the half of the whole amplitude

Amplitude

Amplitude is the magnitude of change in the oscillating variable with each oscillation within an oscillating system. For example, sound waves in air are oscillations in atmospheric pressure and their amplitudes are proportional to the change in pressure during one oscillation...

 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

Data compression

In computer science and information theory, data compression, source coding or bit-rate reduction is the process of encoding information using fewer bits than the original representation would use....

 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

Run-length encoding

Run-length encoding is a very simple form of data compression in which runs of data are stored as a single data value and count, rather than as the original run...

. This is done (in the transform domain) in the Progressive Graphics File

Progressive Graphics File

PGF is a wavelet-based bitmapped image format that employs lossless and lossy data compression. PGF was created to improve upon and replace the JPEG format...

 image format, for instance.

Programs

Many image processing packages can split an image into bit-planes. Open source tools such as Pamarith from Netpbm

Netpbm

Netpbm is an open source package of graphics programs and a programming library, used mainly in the Unix world. It is a highly portable package, working under many Unix platforms, Windows, Mac OS X, VMS, Amiga OS and others and is included in all major open source Unix-like operating system...

 and Convert from ImageMagick

ImageMagick

ImageMagick is an open source software suite for displaying, converting, and editing raster image files. It can read and write over 100 image file formats. ImageMagick is licensed under the Apache 2.0 license.- Features and capabilities:...

can be used to generate bit-planes.