6. Calibration |

6. Calibration

Definition

Graphic image received from camera or by any other way does not give the information on real object sizes. In order to analyze real sizes and conduct measurements, you need to make calibration. Calibration of the image is carried out with the help of the special image.
 
Creating calibration is the process of defining the relation of real sizes to the sizes received at the image, that means, defining the scale for these capture conditions. The process of creating is carried out by application operator. In most cases the calibration is created according to the object micrometer image, but it also can be carried out according to other objects with known sizes. The aim of the operator is to match the micrometer notches with the micrometer figure of the application.
 

Tasks and opportunities

Applying calibration to the image we inform the application on the objects scale at the image. After application of the calibration to the image, the operator has all measurement means of the application. Measurements in document can be carried out only after applying calibration to it. For each capture condition (camera resolution, microscope label and lens) there should be created its own calibration. Calibration is carried out by means of pixels measuring in the micrometer image.
 
Calibration creating
 

Calling the panel

Open the document with the micrometer image (this can be a made micrometer photo or the micrometer view from camera). Launch the creating calibration dialogue in the ToolsCreate calibration menu. The dialogue of creating/editing calibration shall be opened.
 
 

The panel description

 

  • Match the vector scale with the micrometer notches in the photo.
  • In the real length field indicate the length and the measuring units corresponding to the vector scale. The vector scale has five divisions. The length is indicated for the whole image, not for a separate unit.
  • Indicate the name — short name of the calibration. We strongly recommend to indicate in the name of calibration the main data on conditions in which it was made.
  • Description — we recommend to indicate in this field (with all possible details) the conditions in which the calibration was made: lens, camera resolution, enlargement, etc. You can add to the description any information which shall help you later to identify the calibration.

 
 
After make all necessary actions click ОК.
 
You can manage calibrations in Calibrations panel (ViewPanelsCalibrations):
 
Calibrations
 
All created calibrations are shown in the list, the operator, by selecting one of them and clicking the Apply button, applies the calibration to the document. The Delete button allows to delete calibration from the computer (without possibility of restoring!). The Edit button allows to watch and edit the earlier created calibration.
 
If you save the calibrated image in adfx, than calibration is saved by all next launches.
 
 

Example

Let us look at the object micrometer photo.
 
Micrometer
 
The division value of the micrometer is 10 microns, thus, 5 divisions equal to 50 microns. At the received micrometer photo the distance occupied by micrometer is 803 pixels (the above image is decreased for convenience). According to available data we make a conclusion that 1 pixel equals to 50/803 = 0.0623 microns. Having made the corresponding measurements we, by that, have calibrated the image. Now we can assess the real sizes of objects according to images received in the same conditions as the micrometer photo according to which we calibrated.
 
Calibration should be applied only to images received in the same conditions in which the photo of object according to which the calibration had been received.
 
The saved file is a source of calibration and can be viewed and edited later (Edit button at the Calibrations panel), which can be used for control of measurements accuracy.
 
Calibration for current conditions can be saved, so, you do not have to create calibration in cases when capture conditions (camera resolution, microscope label and lens) did not change.