Can you tell me the formula or algorithm for the operation of the photoshop "High Pass" filter?

Question

Adobe Photoshop

Has anyone seen the implementation or formula for calculating this algorithm?
High Pass performs a very simple operation: it finds the difference between the brightness of the original and Gaussian blurred images and shows it as a deviation from the average brightness (tone 128).
But I'm not sure if that's the case, thanks in advance

Answer 1

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