[Bugfix] Missing thumbnail from NVLM-D processor

[ameyanjarlekar]

If num_patches evaluate to 1 for the input image prompt, the existing code does not generate any image token leading to the error "Unable to allocate 256 multimodal tokens to 0 placeholders". For images of particular dimensions eg. 220x229 or 200x229, I received this error.

The code currently breaks the input image prompt into multiple images by cropping certain parts of the image. It then appends all these cropped images plus a thumbnail image which is the resized version of the original image into a list. The number of elements in this list is dependent on the num_patches variable which is calculated based on the size of the original image.

If the num_patches variable is 1, then the code currently does not crop the image and also doesn't add the thumbnail image, therefore adding 0 image placeholders. Therefore, to consider the thumbnail image, which is the original image when num_patches==1 we need to remove the condition num_patches != 1.

To reproduce the bug you can try giving a prompt with this image (https://github.com/user-attachments/assets/7cd2df26-c765-43d8-bab2-9783d33c792f).

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[DarkLight1337]

Thanks for fixing! @kylehh can you confirm this fix since I don't have the means to run this model locally right now.