Some letters survived the vectorization with distortion, but most letters were discarded. Losing the letters is not a big issue; post conversion editing would want to delete the annotation and replace it with text rather than curves. Thin lines crossing at a shallow angle made filled regions, and intersecting outlines of filled region became confused; see lower right corner. The tracing also has some odd features. Many black outlines touch, so they become a large, complicated, object rather than just outlines for specific regions. Instead of just background, a rectangular white region separates the two outlined rectangles. The objects labeled "op", "rp", and "rr" are not simple layered shapes; the desired result would have "rr" overlaid by "rp" which is overlaid by "op". Vectorization is effective on single colored, non gradient input data, like signatures. Vectorization is usually inappropriate for continuous tone images such as portraits. The result is often poor. For example, many different image tracing algorithms were applied to a 25 kB JPEG image. The resulting vector images are at least a factor of ten larger and may have pronounced posterization effects when a small number of colors are used.