Checker Board Pixel Check

[JustinCase24]

Hi,

I am trying to verify the pixels on a small display (160x102) are all working correctly. One of the test images uses a checkerboard pattern to test for shorts between pixels. The goal is to add the captured image to an inverse checkerboard pattern and check for any anomalies. 

The .vi I have written so far applies a threshold, finds the edges of the screen, rotates, and extracts the ROI. 

The problem I am having is when i try to resample the captured image (roughly 928x595) to the resolution of the screen/checkerboard (160x102), it is littered with false positives regardless of the threshold setting or interpolation type.

This may be the wrong approach alltogether however.

Attached is a cropped sample of the original image, the image with a threshold applied, and the image after resampling.

Any advice or help would be greatly appreciated. 

[JustinCase24]

Another approach i am experimenting with is: "The checkerboard image is binarized using a morphology-based adaptive thresholding algorithm, and the pixels are highlighted using blob analysis and filtering routines"

such as used in an ETCs DisplayCheck, however it may take a while to get a function such as this functioning. 

[b.ploetzeneder]

I think you are making your own life too hard:

- If you want to subtract, don't downsample your source image. You are losing information. Upsample your subtraction image.

- Do you really need this? I created a second, test image with 4 errors put into it (attached). When using "Golden Template Matching", I immediately found the errors in there. It depends a bit on your test image quality and how well you can align the images..
- You can always go the texture defect / Wavelot route for this..

[GuenterMueller]

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@JustinCase24 wrote:

Another approach i am experimenting with is: "The checkerboard image is binarized using a morphology-based adaptive thresholding algorithm, and the pixels are highlighted using blob analysis and filtering routines"

such as used in an ETCs DisplayCheck, however it may take a while to get a function such as this functioning. 

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Can you put some light on what a "ETCs DisplayCheck" is?  I have never heard about that...

Edit:  I found it by reading this article...