* colorthres.c: validate input chroma.
* erase.c: fix bluring application limit (prevents out of bounds access).
* gaussianblur.c: validate input chroma and add planar YUV 4:2:2 support.
* psychedelic.c: check image_Convert return value (it fails for I422 which would then trigger a segfault due to a NULL pointer being dereferenced).
* rotate.c: validate input chroma, add planar YUV 4:2:2 support and misc code fixes or simplifications.