How to resize & crop images
If you resize images the easy way, they are either distorted or have different aspect ratios after conversion. So if you need the same image sizes after conversion, independent of the original input sizes, what you need to do is to resize and crop the image. First you resize the image so that the width and length are at least the size of the required output format - then you crop the image and cut off the borders either on the left & right or the top & bottom. Sometimes parts are missing, but this forces users to upload proper images the next time ;-)
here you go:
convert input.jpg -resize “88x” -resize “x88<” -gravity center -crop 88×88+0+0 output.jpg