Describing be a little more precise in this case and will then be easier to answer.
All posters imported via Imdb Movie Photo script are having the same size, which is 214x317 px. I guess it is not a coincidence, but is coded or set up somewhere. I could not find any settings in the graphical interface in order to adjust the mentioned picture size, so my next guess would be setting it up in script. Where can I find such a setting?
No, setting them does not exist or can not be found in the script, maybe in the future, if I found out how this feature to add to the script.
BTW:The script should download the poster already mentioned sizes or more different sizes because the code is modified, so that the possible transmission of larger size - that is, depending on the size of posters on IMDB movie sites (record for the source code page).