Upload the graph image. Select X-axis and Y-axis scales and enter axis ranges. Align the vertical cursor with known X-axis values, click to add points, then click "Apply X-Axis Calibration". Align the horizontal cursor with known Y-axis values, click to add points, then click "Apply Y-Axis Calibration". Use the magnifying glass to guide calibration and point placement. Select a series, click on the curve to place points. Click "Fit Curve" to generate the plot and calculate noise.