One method is to use your gallery images. You can get all the adult images you want that way.

Load your image into your graphic editor program

Convert image to black and white or gray scale

Next use the find edges filter.

The result is of the type of image you want.

You may have to go and clean up some of it to remove unwanted tones and/or enhance the outlines.

Experiment with other filters for the right combination.

I have used this many times.

If you want this type of thing on an internet site you will have definitely use raster images (.jpg, .gif etc) as browsers do not support vector images (except fonts).