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Why Do I Lose the Calibration of an Image After Running the Image Mask from ROI Step?



Primary Software: Vision Assistant
Primary Software Version: N/A
Primary Software Fixed Version: N/A
Secondary Software: Vision Development Module

Problem:
Why do I lose the calibration of an image after running the Image Mask from ROI step?

Solution:
It is possible to build a script that calibrates a grayscale image and performs particle analysis to find the dimensions of objects using the real-world scale from the calibration.  This calibration is performed using two user-defined points.

The script consists of Original Image, Calibrate Image, Image Mask from ROI, Threshold, Remove Small Objects, and Particle Analysis. You may find that the results of the analysis are still in units of pixels.  Ensure that you have not selected Extract Masked Region in the Image Mask from ROI step. That step modifies the dimensions of the image. Any step or action that modifies the image dimensions will result in a loss of calibration. The system has no way to identify if the change of dimensions was due to resizing, resampling, or another alteration of the image that would affect the calibration settings. In order to avoid misinterpreting calibrated data, the units are changed back to pixels.

Related Links:
KnowledgeBase 3EIFDBCH: Common Errors and Issues When Using Pattern Matching with NI Vision
KnowledgeBase 3FDHO5CH: IMAQ Vision Algorithms
NI Vision Help: NI Vision Concepts Help

Attachments:





Report Date: 09/11/2001
Last Updated: 01/25/2017
Document ID: 2DAGKFYJ

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