Image display
The image display module displays all received localizations in an image and optionally saves this image to a file.
The image construction is performed with the algorithm documented in [WolterDiplomarbeit]. Summarizing this algorithm, a localization density map is constructed by linearly interpolating and accumulating the localizations, weighted by their amplitude, on a pixel lattice. This density map is discretized with a very high depth to generate a high dynamic range image; this high-dynamic range image is reduced to a displayable range via weighted histogram equalization.
The histogram equalization operation modifies the absolute brightness differences between image areas to optimize contrast. This means that a pixel in the result image with a brightness of 200 did not necessarily receive twice as many localizations as a pixel with brightness 100 did. Histogram equalizations guarantees only that a brighter pixel represents at least as many localizations as a weaker pixel.
You can change the extent to which histogram equalization is performed by changing the histogram equalization power between 0 and 1. 0 means no histogram equalization, and pixel values are linear with localization density. 1 means full equalization: All brightness values appear equally often in the image. While images without histogram equalization aplied often suffer in contrast due to few, very bright pixels suppressing the normal structures, too much histogram equalization overemphasises regions with weak signals and background noise. The default value for the histogram power is usually a good compromise.
Several different coloring schemes are available for the resulting image. All of these operate on the histogram-normalized brightness, but display the brightness in various ways to enhance information depth, produce a pretty-looking image or give information about the time coordinate. All of these color schemes show brighter colors to indicate more localizations; to invert this meaning and show, for example, black localizations on a white background, use the "Invert colours" option.
The black and white colour scheme is the fastest colour code. It displays the equalized brightness directly on a scale ranging from black (no localizations) to white (maximum amount).
The black, red, yellow and white colour scheme offers a higher dynamic range by displaying the lowest third of the brightness values on a scale ranging from black to red, the middle third on a scale from red to yellow and the highest third on a scale from yellow to white. In total, about 760 brightness levels are displayed.
The constant colour colour scheme is similar to the black-and-white scheme, but uses an arbitray colour instead of white. You can use the "Select colour hue" and "Select saturation" to choose the colour.
The Vary hue by time coordinate colour scheme colour-codes each localization by its time coordinate, that is, by the number of the image it occured in. The code starts at the hue selected in "Select colour hue" and then follows the colour circle of the HSV colour model, that is, ranges from red over yellow, green, cyan, blue to violet. If multiple localizations contribute to the same pixel, hue and variance are interpreted as angle and radius on a plane, converted to cartesian coordinates, averaged arithmetically and converted back to hue and variance. For example, if red (hue 0, saturation 1) and yellow-green (hue 0.25, saturation 1) are present with amplitudes 1 and 4 on a pixel, they are converted to the points (1,0) and (0,1), averaged to (0.2,0.8) and transformed back to (hue 0.21, saturation 0.82), which is a slightly pale yellow. Observe that a point with localizations equally distributed over a long range of images tends to have a low saturation, that is, appear white.
If a Repeater service is available through a parent module, most image display parameters can be changed even after the job is started.
If a filename is given here, the final result image will be saved to the given file. The file extension determines the file type, and all common file formats (GIF, JPG, PNG, TIF) are supported.
If this checkbox is checked, the result image will be shown online in an image window. Disable for faster computation.
Set the aspect ratio of source (camera detector) pixels to target pixels. If set to 10, for example, the result image will be have 10 times more pixels in X direction and 10 times more pixels in Y direction.
Select one of the color schemes given in the section called “Color coding”.
Invert the color display. Each color is inverted among the three primary color axes (red, green, blue), making red to cyan and black to white.
Set the hue for constant color coding or the starting hue for variable hueing. Ranges from 0 (red) over 1/6 (yellow), 1/3 (green), 1/2 (cyan), 2/3 (blue) and 5/6 (violet) to 1 (red again).
Set the saturation for constant color coding. Ranges from 0 (no colors at all, only grey) to 1 (fully saturated colors).
Shows the current resolution enhancement (see job options table for a definition) and allows, if a Repeater service is present, to dynamically change it.
Interactively change the intensity scale of the result image from a linear scale (value 0) to a contrast-enhanced image (value 1).
Control element for zooming in (positive values) or out (negative values) in the displayed image.
Shows and changes the file name where the result image should be written to. The file extension determines the file type, and all common file formats (GIF, JPG, PNG, TIF) are supported.
Save the image at the current state of computation to the file given by Save image to.