I used phpThumb before. Then switched to slir. I still prefer slir with less memory usage, and re-written url. However, slir is not working with external images.
For example, if pointing to /slir/w150/http://external-domain/path-to-image.jpg, it will look into http://my-domain/path-to-image.jpg
Is there any other recommendation for image thumbnail generation please? Searching on google brings some options, but I want to hear from real experiences.