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04/07/2009

Threshold Sliders

Older Documentation: Other Sliders | Threshold Slider & Blobber

The Threshold Slider and the Multi-Threshold Slider (aka Colorizer Slider or Density Slicer) now have similar functions and work in similar ways.  The Multi-Threshold Slider is still useful for colorizing images, but now is able also to extract masks corresponding to the color bands, which is sometimes called Density Slicing, and to sum spectra (from spectral images).

  Both of these sliders color the front image window with the color of the color band, for pixels that are within the intensity range of that band.  The numbers at bottom right indicate the slider settings and percent of image area (or slider range if there is no image open).

You access slider functions via the buttons along the bottom, or by right-clicking on the color bands.

The Slider Button is the old Window Button, and affects what image or images the slider works on.  This is for all sliders made with the Colorize menu.

The File Button is for saving slider settings and colors for later restoration or for note taking.  The Record Note command opens the general note taking page that is accessable from many other places, such as the Help Menu.  The heading for the note is Colorizer Slider because all of the commands in the File Button work for all of the colorizer sliders except the Directional Slider.  The Threshold Sliders are special types of Colorizer Sliders.

The G button is for comparison of the colorized image with the gray level image.  Repeatedly clicking this button turns the colorizing on and off.

The C button applys the color scale to the image.  This is useful when the slider is attached to a new image, to apply the colorization without moving any of the color bars.  Normally, the color is not applied to the image until a slider (an edge or center of a color bar) is moved.

The Info & Mask(s) Button is for printing a table of thresholds and percent image areas, and for making masks of the image that correspond to the values of each color band in the slider.  If a spectral image is open, Plot Spectra will plot a sum spectrum for each color band.  First extract an image, such as a slice or a sum image from the spectrum image (data cube), and use the Multi Threshold slider on that.  Plot Spectra will use the masks from this image along with the corresponding spectra from the front spectral image.

Right-clicking on the color bands allows you to change the thresholds by typing in numerical values, and, in the case of the Multi Threshold Slider, to change the colors, and add and delete color bands.

 

Both sliders have a real time display at the bottom right. 

The Threshold Slider shows the two slider settings and the relevant percent for the red band.  If there is no image, then the slider settings range from 0 - 255, and the percentage is of the slider relative to its full range.  If the slider is working on an image, the slider shows the two thresholds (image pixel intensity values) and the percent of pixels of the image that lie within the two thresholds.

The Multi Threshold Slider displays real time information analogously to the Threshold Slider, except that since there are more than one color band.