Contrast based imaging and analysis computer-implemented method to analyze pulse thermography data for nondestructive evaluation
AssigneeThe United States of America as represented by the Administrator of the National Aeronautics and Space Administration
InventorAjay M. Koshti
Life of this patent
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Abstract
Methods and systems for analyzing and processing digital data comprising a plurality of infra-red (IR) video images acquired by a pulse thermography system are used to compute video data from the raw and smoothed video data acquired for the performance of non-destructive evaluation. New video data types computed may include but are not limited to contrast evolution data such as normalized contrast, converted contrast and normalized temperature contrast. Additionally, video data types computed comprise surface temperature, surface temperature rise and temperature simple contrast.
Claims30
A method to create video data for infrared flash thermography, comprising:
- selecting a frame of a video wherein said video comprises a sequence of frames of surface temperature in terms of pixel intensity of a surface of a material under evaluation after application of a flash of heat;
- selecting a measurement (ROI) region of interest and a reference ROI in said frame;
- computing video data consistent with the following equations for a plurality of frames of said video:
- C
- T
- =
- Δ
-
-
- T
- -
- Δ
-
-
- T
- ref
- Δ
-
-
- T
- +
- Δ
-
-
- T
- ref
- ,
- ΔT=T−T0,
- ΔTref=Tref−Tref0,
- where,
- CT=a normalized temperature contrast at time t,
- ΔT=a change in a pixel temperature of said measurement ROI after said flash of heat,
- T=a pixel temperature at said measurement ROI at a post-flash time t,
- T0=a pixel temperature at said measurement ROI before said flash of heat,
- ΔTref=a change in a pixel temperature of reference ROI after said flash of heat,
- Tref=a pixel temperature at said reference ROI at said post-flash time t, and
- T0ref=a pixel temperature at reference ROI before flash;
- and,
- creating for said plurality of frames additional video data corresponding with the following time derivative:
- a first derivative CT′=dCT/dt.
Dependencies are inferred from the claim text.