plaid

From DavinciWiki

Description

Plaid is column- and row-correlated band-independent noise in THEMIS IR images with a width on the order of 30 pixels. It is most evident in decorrelation stretch images where a multi-color plaid pattern can be seen overlaying the data.

The row-correlated component of plaid is caused by electronic noise in the instrument compounded by artifacts created by the convolution steps in the destripe process. Voltage fluctuations in the instrument electronics manifest themselves as increased or decreased signal over a row as the detector array is read out and stored in memory. These fluctuations are both positive and negative and follow a binomial distribution centered at zero. destripe accurately identifies line-to-line noise and spatially smears the effects over a small (15 pixel) range. The result is that the data retains a low-pass filtered version of the original line-to-line noise.

The column-correlated component of plaid is caused by leftover variations across the samples of the detector that was not removed by the instrument response function. These variations were also spatially convolved by destripe and also follow the same binomial distribution as the row-correlated plaid component.

thm.deplaid is used to remove this line correlated noise. It utilizes knowledge about the statistics of the noise and separation between row- and column-correlated information and band-correlated information such as surface features.

An example image is shown below.