When the Compix® PC2000 takes a thermal image or when a TIFF(.TIF) or Compix(.CPX) image file is opened, the user is relieved from having to deal with many details associated with handling tens of thousands of temperature measurements. Much of the benefit of thermal images rests on the simplification brought about by the display process. To fully utilize the thermal data displayed on the screen it is useful to understand some of the details of the process. This section will explain what the functions are really doing and show how they may be used in combinations in order to get the most out of the thermal images. Before you read this section, please take time to become familiar with the functions and operations of WinTES95 and the PC2000 system.
WinTES95 menus are largely self-explanatory and the system permits risk-free exploration. Once you have saved an image to a named disk file, there is no combination of menu functions which will change the saved data, other than saving another image under the same file name. Therefore, if you try something and don't get the desired result, you can always reload the saved image and try again.
Upon starting WinTES95, the program will look for a camera. If none is found the user will be prompted to start WinTESCheck, the system's diagnostic program. Starting WinTesCheck opens a window on screen. The operator will be prompted for a camera address.
Camera Control, Compix TES for Windows, Thermal Image. Clicking the cursor on any of these windows will make it the active window.
Camera Control Window - This window controls the scan for the PC2000 systems.
Two modes of scanning are available with WinTES95. These are Continual Scan and Single Scan. Continual Scan causes the camera to scan, reset and scan until told to STOP or until Single Scan is selected. Single Scan causes the camera to take a single scan and then stop scanning.
In addition to controlling the scan the operator can control, in continual scan, the time from the start of one scan to the start of the next by setting up a Delay. This is accomplished by clicking the cursor on the delay window and typing in the desired delay (in seconds). A normal scan takes approximately 15 seconds thus a delay of 20(default setting) would have a scan starting every 20 seconds.
The Scan button initiates a scan. The characteristics are determined by the "continual scan/single scan". Switching between continual and single scan may be done at any time.
Switching from Continual Scan to Single Scan will cause the camera to complete the current scan then wait for the next scan command.
The Stop button causes the camera to immediately stop its scanning.
Menus: File, Edit, Compare, Cursor.
File- Sub-menu items: Open File, Save File, Exit.
Open File- Allows operator to open previously saved image, configuration or colormap.
Save File- Allows operator to save an image as a TIFF or as a Compix Image File which retains the full resolution temperature data.
Exit- Terminates the program.
Edit- Sub-menu: Copy. This copies the displayed image to the Windows clipboard from where it can be accessed by other programs.
Compare- Permits the operator to compare images with a reference or previously stored image. Differences between an "unknown" and "golden" board can quickly be determined.
Compare- Sub Menus: Save as Reference Image, Display Reference Image, Revert to Scanned Image, Compare to Reference Image, Compare ALL to Reference Image.
Save as Reference Image- Current image is saved as the reference to which others may be compared.
Display Reference Image- Shows the image currently saved as the reference image.
Revert to Scanned Image- Displays the scanned image.
Compare to Reference Image- The current image is compared against the previously saved reference image. Each pixel, or temperature data point, of the reference image is "subtracted" from the second image
(compared image = current image - reference image).
Compare ALL to reference Image- Every scan is immediately compared with the reference image.
Cursor- Sub Menus: Spot Cursor, Profile Cursor
Spot Cursor- The cursor reads out the temperature of the selected point of the image. This is indicated in the TEMP window of the WinTES95 window.
Profile Cursor- Selecting profile cursor brings up two new windows. These are at the bottom and side of the image window and display a graph of temperature along vertical and horizontal extensions of the cursor crosshair. The range of the measurements corresponds to the minimum and maximum values established by the range control. The cross-hair may be moved using the mouse or the cursor keys. The temperature at the intersection of the horizontal and vertical lines is displayed in the temperature window.
Sub-Window- Color Edit: Contains Image display controls
Colormap- The color scale has five "built-in" display palettes; Default, Rainbow, Blue to Red, Blue-Green-Red and Grayscale. Image files may be displayed in any of these five "colormaps"or palettes. Each is useful for displaying images and personal preferences may dictate the operator's choice.
The palettes contain 234 shades of color or grayscale. Changing color palettes doesn't affect temperatures in the image.
The color scale itself has three display segments. The MAX value is the highest temperature displayed in the color palette. The MIN value is the lowest value displayed in the color palette. The values above and below the MIN and MAX are useful for setting and displaying "overrange values". To set upper or lower control or "overrange" values double click on the color bar. A secondary window will appear and the operator can select a color to signify "over and under range" values. Select the color and tell the program to apply the chosen colors. The top and bottom portions of the colorbar will now display those colors. Subsequent display of images having values outside the colorbar will show the overrange colors where temperatures exceed the range.
AutoRange- Auto range reads the minimum and maximum temperatures in the image and sets the min and max so they encompass the display range. The system automatically redraws the image with the new scale.
AutoScale-Auto scale fits the scale so that one cycle of the colormap is used to display the image data.
Redraw- Refreshes the image. This is done automatically when Autorange or Color Scale are changed. It is not automatically updated when thermal correction factors are changed.
Thermal Correction- This is an auxiliary window which is opened when Correction is clicked. A series of controls are made accessible.
Ambient, Emissivity, Lens factor, Field of view(FOV), Focus(in).
Ambient- Ambient changes can affect the accuracy of absolute temperature measurements. Setting the ambient temperature to the instrument's surroundings compensates for this factor and corrects for errors introduced by ambient variations.
Emissivity- All materials have characteristic emissivities which are less than 1.0. This means that non-black bodies radiate IR at a lower rate than does the ideal source. Practically speaking this means that an object with a lower emissivity will appear to be closer to ambient than a black body having the same temperature. The Emissivity setting corrects for this effect and provides the user with the correct temperature reading for that object. Values can be selected from 1.00 to 0.01.
Lens factor- This correction compensates for the attenuation factor introduced when the system is operated with the 7.5x lens. Without the correction temperatures read by the system would appear lower than their true temperatures. Each lens comes with the its lens factor specified. Nominally this is around 45%.
Focus(in)- Temperature readings can be affected by the distance of the camera from the object being measured. This setting represents the distance from the front of the camera to that object and corrects for any distance related errors.
FOV(Field of View)- This is an indication of the approximate size of the area being scanned.
ColorMap editor- The three color scales display colors which represent temperatures between the indicated minimum and maximum values. There are two bands of colors, one above the Max temp and one below the Min temp called Over Range and Under Range. Their colors may be changed by the operator in a way which emphasizes different aspects of the thermal data. To edit the colors place the cursor on the color scale and double click. A window called ColorMap editor will appear. Double clicking on either the Over Range or Under Range colors will open another window entitled Color. The operator can select the color to represent these extremes. Clicking OK will bring back the ColorMap editor window. Clicking Apply will change the value to that color. Repeat the process for the other range.
Stats(Statistics)- Stats provides the ability for the operator to define an area of the image and have the system report out the min, max, avg. and standard deviation for the temperatures within this area. To define a measurement area, hold down the left mouse button and move the cursor across the image. A "box" will open within the displayed image. Releasing the mouse button will cause a window labeled Stats to appear. Within the window are displayed the maximum, minimum, average temperatures as well as the range of the delta and the standard deviation of the temperatures. Repeating the process anywhere on the image will yield the data for the newly defined "box".
The "box" can be moved across the image by using the Shift key and Arrow keys. Horizontal movement is accomplished by moving one side and then the other through use of the Left/Right arrows and Shift (or no-Shift) keys. Vertical movement is accomplished in similar use of the Shift key and Up and Down arrows instead of Left or Right arrows
Operating Hint: Double clicking in the banner of the Image window will expand the image to full screen size. Double clicking the banner again will reduce it to the previous size.
Statistics: Use this function to compute the average, standard deviation, minimum, maximum and range for a user specified region. When this function is selected, a rectangle appears as the mouse is moved while holding down the left button. The box size is determined by movement of the mouse. The arrow keys or the mouse will move the rectangle.
When the rectangle is positioned and sized as desired, pressing the letter r will compute and display the statistics for the rectangular region. The rectangle is are left on screen for reference, but can be cleared by clicking on Redraw. The area over which the statistics are computed includes the points occupied by the boundary of the rectangle.
Cursor as Profile: This function constructs line graphs of the temperature variation along a horizontal and/or vertical line. When this function is invoked, a menu box appears from which the user must choose which profile graphs are to be drawn: vertical, horizontal, or both.