Remove repeated prepare_images in processor tests (#33163)

* Remove repeated prepare_images

* Address comments - update docstring; explanatory comment

tests/models/instructblip/test_processor_instructblip.py

@@ -15,7 +15,6 @@ import shutil
 import tempfile
 import unittest
 
-import numpy as np
 import pytest
 
 from transformers.testing_utils import require_torch, require_vision
@@ -25,8 +24,6 @@ from ...test_processing_common import ProcessorTesterMixin
 
 
 if is_vision_available():
-    from PIL import Image
-
     from transformers import (
         AutoProcessor,
         BertTokenizerFast,
@@ -64,17 +61,6 @@ class InstructBlipProcessorTest(ProcessorTesterMixin, unittest.TestCase):
     def tearDown(self):
         shutil.rmtree(self.tmpdirname)
 
-    def prepare_image_inputs(self):
-        """This function prepares a list of PIL images, or a list of numpy arrays if one specifies numpify=True,
-        or a list of PyTorch tensors if one specifies torchify=True.
-        """
-
-        image_inputs = [np.random.randint(255, size=(3, 30, 400), dtype=np.uint8)]
-
-        image_inputs = [Image.fromarray(np.moveaxis(x, 0, -1)) for x in image_inputs]
-
-        return image_inputs
-
     def test_save_load_pretrained_additional_features(self):
         processor = InstructBlipProcessor(
             tokenizer=self.get_tokenizer(),