Image Statistics

The Image Statistics algorithm calculates the per-channel minimum, maximum, mean, standard deviation, and histogram data for a given image, or a user-specified sub-region of an image.

Input

The input to the Image Statistics algorithm can be a 2D or 3D image set. The algorithm does not modify the input data in any way.

Output

The results of the Image Statistics algorithm are displayed in a table in the widget that appears when the algorithm is launched. Each row of the table corresponds to a channel of the input image data, and displays the minimum, maximum, mean, and standard deviation of the intensity values for that channel. The final column of the row shows a plot of the histogram of the intensity data. If the input data is a set, the displayed values belong to the element that is currently focused in the selection.

Description

The Image Statistics algorithm can calculate statistics either on the entire image or on a sub-region determined by you. When you launch the algorithm, the statistics for the entire image are calculated and displayed in the results table, unless you choose to select one of the possible pre-existing annotations. In order to see the statistics for a specific sub-region of the image, select the type of sub-region you want by pressing either the Line, Rectangle, or Circle button. To begin drawing the region, press the Draw button.

As you are drawing the region you will notice that the statistics in the results table are being updated in real time. After you have finished drawing the region, you can modify the size or the location of the region, and the statistics will continue to update in real time. This is useful for example if you would like to compare the statistics between two regions of the same size and shape within the same image, or if you would like to comapre the statistics between regions of the same size at the same location on successive frames of a video stream. Simply scroll through the images of the video stream and you will see the statistics update as you jump from one frame to the next.

If you notice that the statistics update is too slow while moving or editing the existing shape, you can uncheck the ‘Live update while editing annotation’ check box to speed up performance. When the box is unchecked, the statistics will only be calculated when you have finished editing or moving the shape, but not during.

You can draw a new region by pressing another shape button followed by the Draw button. You can also re-calculate the statistics on the entire image by pressing the Entire Image button. Note that drawing a new shape or re-calculating the statistics on the entire image will erase any existing shapes and statistics data.

If you already have some of the relevant shapes as annotations in the Annotations list when you launch the Image Statistics algorithm, you will be presented with the option of selecting one of them to use as a region for calculating the image statistics. Simply select the annotation you want to use from the list, and you will see the statistics associated with that sub-region of the image displayed immediately in the results table. Of course, you can edit and manipulate the region as before, and the statistics will be updated in the results table. Please note however, that if you do choose to use an existing annotation for calculating the image statistics, the annoatation will no longer be available for use in the Annotations list.