In the new version of Magick.NET that has just been published you will be able to do read the image even though it is corrupt. You can do that with the new class PngReadDefines. Below is an example:
MagickReadSettings settings = new MagickReadSettings() { Defines = new PngReadDefines() { PreserveCorruptImage = true } }; using (MagickImage image = new MagickImage()) { try { image.Read("Corrupt.png", settings); } catch (MagickCoderErrorException) { // Do something with the image. } }