An RMagick user is having trouble with corrupted TIFF images. He is processing about 16,000 images. Some are 2048x3072, the rest are 1024x1536. About 50 of the output images are corrupt. Each time he repeats the processing a different set of output images are corrupted. He is not able to predict which images will be affected. Here is one of the corrupt images: http://www.saskia.com/download/aam0711.zip. He says that all of the corrupt images look roughly the same - the odd rectangle is always in the upper-left corner and there are usually extraneous horizontal lines across the image. The corrupt image files are larger than non-corrupt images with the same dimensions and Photoshop reports the wrong image file size (4.46M for an 8.3M image, for example). The user processes these images by reading the image, resizing it, using unsharp-mask, and then writing the image to disk.
The user is running ImageMagick 6.3.0-Q16.
Can you give me any advice about how to narrow down the problem or help you to diagnose it? Would an example of one of the input images help?