ISO 18381:2013 pdf free

ISO 18381:2013 pdf free.Space data and information transfer systems – Lossless multispectral and hyperspectral image compression
This Recommended Standard defines a payload lossless data compressor that has applicability to multispectral and hyperspectral imagers and sounders. This Recommended Standard does not attempt to explain the theory underlying the compression algorithm; that theory is partially addressed in reference [C1].
The input to the compressor is an image, which is a three-dimensional array of integer sample values, as specified in section 3. The compressed image output from the compressor is an encoded bitstream from which the input image can be recovered exactly. Because of variations in image content, the length of compressed images will vary from image to image.That is, the compressed image is variabl-length.
A user may choose to partition the output of an imaging instrument into smaller images that are separately compressed, e.g., to limit the impact of data loss or corruption on the communications channel, or to limit the maximum possible size of a compressed image. This Recommended Standard does not address such partitioning or the tradeoffs associated with selecting the size of images produced under such partitioning. Reference [C1] presents some examples.
The compressor consists of two functional parts, depicted in figure 2-1: a predictor and an encoder.
The predictor, specified in section 4, uses an adaptive linear prediction method to predict the value of each image sample based on the values of nearby samples in a small three-dimensional neighborhood. Prediction is performed sequentially in a single pass. The prediction residual, i.e., the difference between the predicted and actual sample values, is then mapped to an unsigned integer that can be represented using the same number of bits as the input data sample. These mapped prediction residuals make up the predictor output.
The compressed image, specified in section 5, consists of a header that encodes image and compression parameters followed by a body, produced by an entropy coder which losslessly encodes the mapped prediction residuals. Entropy coder parameters are adaptively adjusted during this process to adapt to changes in the statistics of the mapped prediction residuals.ISO 18381 pdf download.