SPACE to pause/resume the slideshow. The images here are presented in order: Original / ETF / smoothed ETF / drawing You may be able to use data extracted from the smoothed ETF to augment other algorithms. For example a dithering/pointillist algorithm could use slightly elliptical dots instead of circles, and orient them along the ETF. Or an oil painting could apply brushstrokes in the orientation of the lines of the image.
The algorithm comes from http://www.cs.umsl.edu/~kang/Papers/kang_npar07.html and the C code is at http://gtoal.com/cld/C/ This is actually computed offline, it will be a lot of effort to convert this code to Scratch. However what I can do is use the c code to generate the "Edge Tangent Field" data for this image and supply that data for Scratchers to use in other projects, eg selecting the orientation of brush strokes... In the third image - the smoothed ETF - each pixel encodes the X, Y vector and Magnitude in the R, G, B values. X and Y are normalised around 128 which represents 0.
