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Release Notes


ColorSegmentor - 57
Color images are normally acquired in RGB format.  This format is most efficient for display of colors.  For image processing applications the HSI is a better choice.  The HSI color model represents every color with three components: hue (H), saturation (S), intensity (I). The figure below illustrates how the HSI color space represents colors.











The H value identifies the color and is normally represented with an angle [0..360].  The S value is normalized to [0..1] and describes
how far away from the grayscale the color is.  A value of 1.0 is said to identify a pure color.  The I value describes the amount of white present in the color.  A value of 0.5 gives the colors that are the purest - that is the distance from the grayscale is at its maximum.  An S value of 0.0 gives the grayscale leaving the H value meaningless. S=0 and I=0 is black. S=0 and I=1 is white.

The ColorSegmentor tool does not represent HSI values as [0..360], [0..1], [0..1].  Instead the values are represented using discrete
8 bit values [0..255], [0..255], [0..255].  The H value is placed with 0 at Red as in the HSI model.  This places Red at 0, Yellow at 43, Green at 85, Cyan at 128, Blue at 213 and Magenta at 213.  The S values is 0 for a grayscale image and 255 for a fully saturated color.  The intensity is 0 for black and 255 for white with fully saturated colors at 128.

The ColorSegmentor tool takes a color image as input and produces a single output grey scale image:


The tool performs a segmentation of a color image by converting the RGB values into HSI values.  Then a set of specified filters are applied.  You may set any pixel matching the filter to a defined value say black = 0.  The resulting image is then output to a specified image which you have created with the property Active=0.  All pixels not matching the filter specification may be set to a fixed value.  Alternatively you may have either of the HSI images output.

Lets go through the necessary steps to apply some color segmenting.

First we create two images:

  • im
  • segmented

The im image will load the HSI color model presented previously, as a color image.  This is our input image.

The segmented image will receive the output image from the color segmentor tool.

When we click on the segmented image we can set the Active property to un-ticked.  This is necessary as the image is not originating from a camera but from a Scorpion tool.  

Note: If you forget to do this Scorpion will appear to be hanging when grabbing images.

The next step to perform is to add a ColorSegmentor tool.  Got to the toolbox - press New and do so.

Then double click on the tool to activate the configuration dialog.

The configuration dialog contains the tabs:

  • General
  • Setup
  • Visualization
  • Results

In the General tab we specify the index of the input image which in this case is 1. 


In the Setup tab we will do the required work to segment the image.

The ROI may be ticked and specified as a sub region of the input image.  If left un-ticked we will operate on the full image.

Point & Click Clipboard Support

The rectangular ROI is defined by four points.

 One point will change the center point.

More on Image Operations.

As usual we may specify a reference for the ROI, but this is not necessary when we process all of the input image.

The really interesting part is the Filters.  By pressing the + sign we may add new filters.  The filters may be copied and pasted to our convenience, or rearranged in sequence if desired.

Note that we may specify a range for H, S and I.  Also we may specify a Mask.  The regions in the input image matching the filters will have the mask forced to the mask value in the output image.  In our example we force this value to 0 or black.

We will try to segment out yellow contents.  In the HSI model this equals values centered around 60 degrees.  In the 8 bit representation in the ColorSegmentor tool this maps to an 8bit value of 42.  We add some tolerance to this value to pick up neighboring colors as well.

We seek values with close to maximum saturation which starts at an I value of 0.5 or 128 in our case.  We add some slack to this value as well.

We have to specify the Transfer to image property which is the artificial image segmented we created a few steps ago.  In the example we choose to force all values not matching the filters to the fixed value of 255.  In this way we will binarize the output image to 0 and 255 where yellowish contents will map to 0.

The Active filters may contain a list of regular expressions separated by semicolon ";" used for activation of the individual filters by name due to the regular expressions match.

Finally, the segmented output image may be filtered, see available filter commands.

Here is the HSI Filter dialog.  Note that only H and I ranges are specified as we are interested in the full saturation range 0..1.  When applied to the HSI model image this should result in:
  • A black dot where the yellow color is indicated in the HSI cone
  • A small pie
  • A larger pie

Here is the output which is produced when we press the Snapshot button followed by the Inspect button.

The result was more or less what we wanted!

The first time you press Inspect, Scorpion will be busy in several seconds depending on the processing power on the host computer.

This is due to the fact that the first time the tool is run, an RGB to HSI lookup table is loaded.  This LUT is 32MB and consumes some cpu cycles.

Note : Check Load HSI color conversion file at startup under Service.General.Options to load the file when starting Scorpion.

Subsequent Inspect will not be penalized and the tool will execute promptly.

Because HUE is defined as a cyclic value with wraparound between 360 and 0 degrees (in the HSI model), or 255 and 0 8bit values (in our model), we need to apply a special filter to cover the range spanning the RED color.

Lets modify our example to pick up red colors.

  • Add a new filter S from 50 to 225
    • value with S below 50 is normally no color - removing this filter will add white and black content
  • Set the H filter to 10 to 240
    • Check Mask outside band
    • The following H values are accepted 0 to 10 and 240 to 255

We should now be able to segment red contents

Voila!  The result image now indicates that we have isolated:

  • The red dot at 0 degrees in the HSI cone
  • The small red pie
  • The large red pie

Note that you may use the color segmentor to only extract the black content - no color. 

The filter :

  • S [0..40]
  • I [0..60]

will pick up the black contents in the image and yield the following segmented image:











ExecuteCmd support (see also executeCmd)



Return values


Set Object=ROI;Value=<polygon>
Sets the tool's ROI. See Copy/paste ROIs for details.
Get Object=ROI ok,<polygon> Current ROI as rectangular, closed polygon

Scorpion Vision Version XII : Build 646 - Date: 20170225
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