Threshold

From the Threshold dialog box, you can specify a value as the threshold of the image, so all the pixels lighter than the threshold will be converted to white and all the pixels darker than the threshold will be converted to black. Consequently, the image will turn into a high-contrast, black-and-white image and it will become much sharper. This function is generally used in the scanning of black-and-white images or text to clear noise. To decrease the threshold, drag the slider under the diagram to left, and the black color will be increased. You can increase the white color by dragging the slider to the right. In addition, you can directly enter the desired value in the entry box to adjust the threshold. When you get the desired effect, press the OK button to confirm your settings and close the dialog box. Otherwise, press the Reset button to reset the brightness and contrast, or you can press the Cancel button to cancel your settings and close the dialog box.