Contour Plot


The Contour Plot command draws one or more intensity contours on an image. The contour plotting commands operate from the Contour Plot Toolbar. Contours are generated at specified levels. The related Interactive Contour Plot command allows you to mark the level where a single contour is to be created. Contouring can be done on the entire image or within the rectangular region of interest ("ROI") specified by the image cursor. Generally, it is best to contour within the cursor rectangle. To move and resize the cursor, use Ctrl+A to toggle cursor mode on and off.

Use the toolbar button (see below) to control the contours by setting Contour Plot Properties such as level values and colors.

 

Toolbar Commands

The Contour Plot Toolbar controls the process for drawing contours on an image. This toolbar is opened from the top-level Image Plot Toolbar or the Plot > Contour Toolbar menu command.

Procedure

  1. Open the Contour Plot dialog by clicking the button on the Image Plot Toolbar. The first time, this opens the Contour Plot dialog where the properties are set.

  2. In the Contour Plot dialog, set the properties, then click [Plot] to generate the contours. Click [Close] to close the dialog. There are two strategies for defining the contour levels:

  1. When you close the Contour Plot dialog the first time, the Contour Plot Toolbar appear at the edge of the Image window.

  2. To close the Contour Plot Toolbar, click the button again on the Image Plot Toolbar.

  3. After plotting contours, you can delete each one separately in "Delete Mode" by clicking the button on the Contour Plot Toolbar. In this mode, you point at and click on the target contour drawn on the image. Alternatively, all contours will be erased when you close the Contour Plot Toolbar as in step 4. You can delete all contours using the button.

Remarks

Tip

It is usually advisable to use the Image Cursor to constrain the contouring to the minimum necessary rectangle. Contours require drawing many short lines, and a complex contour containing a huge number of line segments may cause the computer to lag when redrawing the window.

 

With many complex contours visible, display updating is sluggish. You can see this when you adjust the palette or move the image cursor. To cure that problem, simplify the contours, increase smoothing, shrink the contour region, or delete the contour using the (delete all) button on the contour toolbar.

Contouring Regions of High Noise Level

Below is shown a magnified view of the image above with a single contour having many wiggles. This contour was created using Smoothing = low, which creates many wiggles as the contour tracks through noisy, low level pixels. For more information about contour plotting in noisy areas of an image, see Contour Plot Smoothing.

Tip

You can terminate the contour computation at any time by hitting the [Esc]key. This is especially handy if you start a contour computation after accidentally clicking on a level too far into the noise.

Related Topics

Plotting Commands

Contour Plot Properties

Contour Drawing Properties

Interactive Contour Plot

Contour Plot Smoothing


Mira Pro x64 User's Guide, Copyright Ⓒ 2023 Mirametrics, Inc. All Rights Reserved.