Measuring images  
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ImageWarp provides a number of tools for interactive and automatic measurements of images. Before you start collecting measurement data from an image, you have to calibrate it in order to map pixel coordinates and/or their values to the engineering units of the physical world.

To calibrate an image spatially
 
1.Acquire an image containing an object of known length (e.g. a ruler or object-micrometer).  
 
2.viewrulers Click the Show Rulers button on the View toolbar. Two coordinate rulers will appear on the top and left sides of the active image.  
 
3.Double click the horizontal or vertical ruler. The Spatial Calibration dialog box will open.  
 
4.Check the Lock box (this assumes that your image is not stretched vertically or horizontally).  
 
5.Choose the unit for spatial measurements and enter it into the Unit field (e.g. "mkm")  
 
6.Click the Define button to switch to the interactive mode.  
 
7.Draw a line of known length by marking the starting and ending points with mouse clicks.  
 
8.Enter the length of the drawn segment in calibrated units as prompted.  
 
9.Click the Done button to exit the interactive mode.  
 
10.Click the Apply button to apply the new calibration scale to your image.  
 
To calibrate an image optically
 
1.Acquire an image containing an object with known intensity grades (such as an optical wedge).  
 
2.From the Measure menu select Intensity Calibration.  
 
3.Choose the unit for intensity measurements and enter it into the Unit field (e.g. "lux")  
4.eyedropper In the Intensity Calibration dialog box select the Sampling tool.  
 
5.Mark the points of known intensity by clicking in the image.  
 
6.Deselect the Sampling tool to exit the interactive mode.  
 
7.Enter the corresponding intensity values in the Output column of the Reference table.  
 
8.From the Fitting list box select a fitting method for building the intensity curve.  
 
9.Click the Apply button to apply the intensity scale to your image.  

To generate the histogram of an image
 
1.Activate an image for which you want to generate the histogram.  
 
2.drawrectselect drawfreeselect Using the selection tools from the Draw toolbar, define a region of interest in the image.  
 
3.viewhistogram Click the Show Histogram button on the View toolbar to open the Histogram window.  
 
4.Click the More button to display the histogram statistics and access additional options.  
 
5.Move the cursor over the graph to display the information on individual histogram bins.  
 
6.Define a new selection area in the image to generate the histogram for this area.  
 
7.filesave Click the Save button to store the histogram data in a file.  

To generate the line profile
 
1.Activate an image for which you want to generate the line profile.  
 
2.profile Click the Show Profile button on the View toolbar to open the Line Profile window.  
 
3.From the Shape list box select Vertical, Horizontal, Ellipse or Freehand line.  
 
4.To define a freehand shape, click the New button and drag in the image.  
 
5.To add a straight segment to your line, release the mouse button, move the cursor to the endpoint of the segment and continue drawing.  
 
6.To end the line definition, click the right mouse button.  
 
7.To move the profile line, position the cursor over it and drag it to the new location.  
 
8.Click the More button to display the profile statistics and access the extra options.  
 
9.Move the cursor over the graph to display the information on individual profile points.  
 
10.filesave Click the Save button to store the profile data in a file.  

To perform point measurements
 
1.measpoints On the Measure toolbar click the Point Measurements button.  
 
2.Click the Parameters button in the Point Measurements dialog box.  
 
3.Select the desired parameters for measurements.  
 
4.Adjust the size of the measurement zone with the Size option.  
 
5.Mark the points of interest by clicking in the image.  
 
6.To select a different class of measurements, change the Class option.  
 
7.To move an already defined point hold down the SHIFT key, position the cursor over the point and drag it to the new location  
 
8.Click a row in the data table to make the corresponding point in the image blink.  
 
9.filesave Click the Save button to store the measurements data in a file.  
 
To perform line measurements
 
1.measlines On the Measure toolbar click the Line Measurements button.  
 
2.Click the Parameters button in the Line Measurements dialog box.  
 
3.Select the desired parameters for measurements.  
 
4.Define line features by clicking the left mouse button at the start and end points of the lines.  
 
5.To move an already defined line hold down the SHIFT key, position the cursor over the point and drag it to the new location  
 
6.Click a row in the data table to make the corresponding line in the image blink.  
 
7.filesave Click the Save button to store the measurements data in a file.  

To perform contour measurements
 
1.meascontours On the Measure toolbar click the Contour Measurements button.  
 
2.Click the Parameters button in the Contour Measurements dialog box.  
 
3.Select the desired parameters for measurements.  
 
4.Drag in the image to define a contour feature.  
 
5.To add a straight segment to the feature, release the right mouse button, move the cursor to the endpoint of the segment and click to anchor the point.  
 
6.To erase recently drawn segments, hold down the BACKSPACE key until you have erased all the points for the desired segment  
 
7.To enclose the contour feature, double click or press the right mouse button.  
 
8.Continue to define new contour features and see the measurement data displayed in the table.  
 
9.To change the class of features, use the Class option.  
 
10.To move an already defined contour feature hold down the SHIFT key, position the cursor over the contour and drag it to the new location  
 
11.Click a row in the data table to make the corresponding contour in the image blink.  
 
12.filesave Click the Save button to store the measurements data in a file.  

To perform manual blob measurements
 
1.Segment your original image to a binary or multiphase one using the thresholding or other segmentation functions (see Processing_images).  
 
2.measblobs On the Measure toolbar click the Blob Measurements button. This will open the Blob Measurements dialog box.  
 
3.Select the binary (multiphase) image as the Input mask and the original grayscale or color image as the Photo reference.  
 
4.Click the Parameters button Select the desired parameters for measurements.  
 
5.Select the features of interest by pointing and clicking the left mouse button.  
 
6.To change the class of features, use the Class option. The blobs of a different class will be highlighted with a different color.  
 
7.Continue to select new blob features and see the measurement data displayed in the table.  
 
8.Click a row in the data table to make the corresponding object in the image blink.  
 
9.filesave Click the Save button to store the measurements data in a file.  
 
To perform automatic blob measurements
 
1.Segment your original image to a binary or multiphase one using the thresholding or other segmentation function.  
 
2.From the Measure menu select Parameters and choose the desired parameters for automatic measurements..  
 
3.From the Measure menu select Blob Measurements->Automatic. This will open the Automatic Measurements dialog box.  
 
4.Click the Binary objects tab.  
 
5.Select the binary (multiphase) image as the Input mask and the original grayscale or color image as the Photo reference.  
 
6.Click the Data file button and enter the file to which the measurement data will be written. You can also leave the File name field blank to output the results to the global data table.  
 
7.   Click Apply to execute automatic measurements.