For each image you want to decensor, using image editing software like Photoshop or GIMP to color the areas you want to decensor the green color (0,255,0), which is a very bright green color and be sure that the picture you use has RGB color Mode not Indexed Color Mode.
I personally use the wand selection tool with anti-aliasing turned off to select the censored regions. I then expand the selections slightly to completely cover the censored areas, pick the color (0,255,0), and use the paint bucket tool on the selected regions.
As with decensoring bar censors, perform the same steps of coloring the censored regions green and putting the colored image into the "decensor_input" folder.
In addition, move the original, uncolored images into the "decensor_input_original" folder. Ensure each original image has the same names as their corresponding colored version in the "decensor_input" folder.
For example, if the original image is called "mermaid.jpg," then you want to put this image in the "decensor_input_original" folder and, after you colored the censored regions, name the colored image "mermaid.png" and move it to the "decensor_input" folder.