## Set up an equation

- The equation for a line y = mx + b
- the slope “m” is image contrast
- the y-intercept “b” is image brightness

- The equation for a line y = mx + b

## What we are doing:

- Write two equations
- one for “paper”
- one for “overwriting”

- Use the mean value of each color channel you chose as points “x” & “y”
- Find values for contrast m and brightness b that are equal for both images
- Alter gray values of one image
- Subtract from other image
- This equalizes the “paper” and “overwriting” to same gray value.

- Write two equations

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