Photoshop

Create a Custom filter

  1. Choose Filter > Other > Custom. The Custom dialog box displays a grid of text boxes into which you can enter numerical values.
  2. Select the center text box, which represents the pixel being evaluated. Enter the value by which you want to multiply that pixel’s brightness value, from –999 to +999.
  3. Select a text box representing an adjacent pixel. Enter the value by which you want the pixel in this position multiplied.

    For example, to multiply the brightness value of the pixel to the immediate right of the current pixel by 2, enter 2 in the text box to the immediate right of the center text box.

  4. Repeat steps 2 and 3 for all pixels to include in the operation. You don’t have to enter values in all the text boxes.
  5. For Scale, enter the value by which to divide the sum of the brightness values of the pixels included in the calculation.
  6. For Offset, enter the value to be added to the result of the scale calculation.
  7. Click OK. The custom filter is applied to each pixel in the image, one at a time.

    Use the Save and Load buttons to save and reuse custom filters.