for i in range(100):
  img = toimage(X_test[i])
  label = results[i].argmax()
  plt.subplot(10, 10, pos)
  plt.imshow(img)
  plt.axis('off')
  plt.title(cifar10_labels[label])
  pos += 1        
plt.show()

を実行してイメージをJupyter notebookに表示させようとしたら、以下のようなエラーが出た。

KeyError Traceback (most recent call last)
/usr/local/lib/python3.6/dist-packages/PIL/Image.py in fromarray(obj, mode)
2415 typekey = (1, 1) + shape[2:], arr['typestr']
-> 2416 mode, rawmode = _fromarray_typemap[typekey]
2417 except KeyError:

KeyError: ((1, 1, 3), '<f4')

During handling of the above exception, another exception occurred:

TypeError Traceback (most recent call last)
1 frames
/usr/local/lib/python3.6/dist-packages/PIL/Image.py in fromarray(obj, mode)
2417 except KeyError:
2418 # print(typekey)
-> 2419 raise TypeError("Cannot handle this data type")
2420 else:
2421 rawmode = mode

TypeError: Cannot handle this data type

コードを以下のように変えると問題が解決した。

for i in range(100):
  scale = 255.0 / np.max(X_test[i])
  img = toimage(np.uint8(X_test[i]*scale))
  label = results[i].argmax()
  plt.subplot(10, 10, pos)
  plt.imshow(img)
  plt.axis('off')
  plt.title(cifar10_labels[label])
  pos += 1        
plt.show()