Many of the images do include a size, see https://api.isic-archive.com/images/?query=clin_size_long_di....

FWIW @sungam - I'm one of the maintainers of the ISIC Archive, so feel free to let me know if finding/downloading data could be made easier. It's always interesting to see people using our data in the wild :)

Thanks for this - and thanks for maintaining this incredibly useful resource. What would be the best way to contact you?

firstname.lastname at kitware dot com.