Create Animated Thumbnails (Image Magick)

I have a script using Image Magick and PHP to create animated thumbnails. It works ok but every now and then for certain images it doesn't create a thumbnail and for black&white images the thumbnail looks off. Here's what my current script looks like: $cmd = $IMPath.'convert'; $cmd .= ' '.$UploadPath.$ranN2.' -coalesce -resize '75x75' -channel A -threshold 10% '.$ThumbPath.$NoExten[0].'[login to view URL]'; exec($cmd); I attached a bunch of images that have trouble working with the script. I would like to get a script that works for all images and resizes to 100x100 maximum dimensions.