Adaptive Thresholding
This filter converts the image to a black-and-white one.
The component selects a square area around every pixel and calculates the threshold value for this area based on the specified value and overall brightness of the area. If the brightness of the pixel is less than the calculated value, then the pixel is replaced with a white one, if the brightness value is greater with a black one. In addition, if the contrast in brightness in the area, that is the difference between maximum and minimum value of brightness, is less than the specified value, the pixel is replaced with a black one (the algorithm is known as Bernsen Thresholding).
| Option | Description |
|---|---|
| Value of square size | Set the size of the area for around each pixel to calculate the brightness threshold for the pixel. When
configuring Adaptive thresholding filter, set Value of square size comparable to
document character thickness.
|
| Value of contrast | Specify the maximum value of contrast in brightness within the area around a pixel, that is, the difference between maximum and minimum values of brightness. If the contrast is less than the specified value, the pixel will be replaced with a white one; otherwise, the brightness of the pixel will be compared to the arithmetical means of max and min values of brightness. |
| Value of threshold | Set threshold value within the range of 0% to 100%. All pixels whose brightness is less than the threshold value will be replaced by black pixels. |
Preview windows controls
| Option | Description |
|---|---|
| Auto preview | If this check box is selected, preview image will be recalculated every time you make a change in the dialog settings. If this box is unchecked, all changes you made will be calculated after you click the Preview button. |
| Quick view | If you are performing filter configuration on a large image file it is advised to check this box to speed up image processing calculation. The program will choose the optimal processing algorithm. |