This menu gives access to a number of routines which correct or enhance an image. These techniques include ensemble averaging, correction for variations in the background illumination and histogram equalisation to make the best use of the available intensity scales.
This option allows a full precision ensemble average to be produced for window within a user specified list of buffers. Note that the standard (quick) averaging using [;GA: ALU acquire] or [;GM: ALU operations on buffer pairs] utilise the onboard ALU which does not compute true averages for more than two frames. If a long time series is to be averaged rather than an ensemble average, the [;TA Average of time series] facility should be used as this is tailored to produce such averages much more efficiently.
Functionally similar to [D Correct dye image for background variations], this option also makes a leading order correction for parallax causing the length of light rays to vary across the field of view.
While it is desirable that the illumination of an experiment is as even as possible, it may still be necessary to make a correction in many cases. Problems may arise (such as the imperfect nature of most diffusers) which can not be corrected by altering the experimental set up, and so a correction must be imposed during the analysis stage.
This facility is designed to try to optimise the usage of the available intensity scale in an attempt to enhance certain features of the image. The cumulative intensity histogram is first evaluated for a user-specified window. The intensity distribution is then modified in an attempt to change this histogram into a straight line or some other suitable form. This modification may be applied to a second user-specified window.
This submenu provides a method for producing an approximate equation describing variations in the background intensity. Up to 13 coefficients may be fitted on up to 2048 blocks within a user-specified window. See the help option within this submenu for more details.
This option allows the creation of a formatted file containing an intensity histogram of a specific window within a buffer. In addition a on-screen plot of either the instantaneous or cumulative histogram may be produced. The mean and standard deviation of the histogram are calculated for the subset of the pixels falling between user-specified lower and upper thresholds. If a cumulative histogram is chosen, the displayed histogram is also scaled on the lower and upper thresholds.
This option attempts to reconstruct the underlying intensity histogram from a knowledge of the measured intensity histogram and the point spread function that alters the intensity histogram through the noise introduced to the system.
This facility allows the intensities in a buffer to be altered in a linear manner by supplying the (real) coefficients a and b for the relation p <-- a + bp.
This option is designed to give an improved signal to noise ratio in the remapped intensities when compared with the standard pixel-by-pixel remapping.
The purpose of this option is to remap the coordinate system of an image. This rempping process allows simple translations, rescalings and more complex transformations to be produced provided the coordinates in the source image (Iold,Jold) may be expressed in terms of the coordinates of the destination image (I,J) by the mapping Iold = iFormula(I,J), Jold = jFormula(I,J).
This option is similar to [A Average of buffers] except that the average is in the RMS sense rather than the aritmetic sense. For generallity, the 'zero' intensity value may be specified.
This option provides access to a menu containing a number of facilities for correcting LIF type images for the attenuation, spreading and diffusion of the illuminating light sheet.
This option is used to combine the intensities of two or more buffers, pixel-by-pixel, using a user-specified formula. The result is written out to a further buffer (which may be the same as one of the source buffers).
DigImage User Documentation