import Image if __name__ == '__main__': img = Image.open('input.png') in_pixels = list(img.getdata()) out_pixels = list() for i in range(len(in_pixels)): r = in_pixels[i][0] g = in_pixels[i][1] b = in_pixels[i][2] out_pixels.append( (255-r, 255-g, 255-b) ) out_img = Image.new(img.mode, img.size) out_img.putdata(out_pixels) out_img.save("output_inverted.png", "PNG") == Audio == * Check the comments * Load in any tool and check the frequency range and do a spectrum analysis. * Use sonic-visualiser and look at the spectrogram for the entire file (both in log scale and linear scale) with a good color contrast scheme. Images can be hidden this way: [[ http://wikiimage.tumblr.com/post/16585634006/a-spectrogram-of-windowlicker-reveals-a-spiral]] == Video/Animation == * Check any metadata before the stream (comments, palette, etc) * Extract individual frames and inspect each * Inspect differentially: each frame with the next (using "compare") or frame 0 with N, frame 1 with N-1 (by XORing or similar) * Tamper with the palette to see movement of colors that are similar and indistinguishable originally