Show that High pass= Original

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written 9.2 years ago by

teamques10 ★ 70k

When we apply the LPF on the image, the center pixel z5 changes to

$\dfrac19[z_1+z_2+z_3+z_4+z_5+z_6+z_7+z_8+z_9]$

Original- Low pass

$= z_5-1/9[z_1+z2+z3+z4+z5+z6+z7+z8+z9] \\ = z_5-1/9[z_1+z_2+z_3+z_4+z_5+z_6+z_7+z_8+z_9] \\ =8/9 z_5-1/9_z1-1/9_z2-1/9_z3-1/9_z4-1/9_z6-1/9_z7-1/9_z8-1/9_z9 \\ =1/9Χ \text{high pass mask}$

-1	-1	-1
-1	8	-1
-1	-1	-1

This is nothing but a high pass mask.

HPF alternates LOW frequency components and allows to pass High frequency components of the image.
HPF is the sharpening Second order derivative filter.
HPF image can be obtained by subtracting LPF image from original image.

enter image description here

Therefore,

Original image = LPF image +HPF image

HPF image=Original image-LPF image

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