ssd-kerasをターミナルで動かす

#はじめに
オブジェクト検出のアルゴリズムのSSDをkerasで実装したリポジトリがあります。

[rykov8/ssd_keras](https://github.com/rykov8/ssd_keras)

こちらにはJupyter用のサンプルコードがありますが、ターミナルですぐ動かせるコードがなかったため、
Jupyter用のサンプルコード(SSD.ipynb)を参考に作成しました。

# コード
```lang:python
import cv2
import keras
from keras.applications.imagenet_utils import preprocess_input
from keras.backend.tensorflow_backend import set_session
from keras.models import Model
from keras.preprocessing import image
import matplotlib.pyplot as plt
import numpy as np
from scipy.misc import imread
import tensorflow as tf

from ssd import SSD300
from ssd_utils import BBoxUtility

plt.rcParams['figure.figsize'] = (8, 8)
plt.rcParams['image.interpolation'] = 'nearest'

np.set_printoptions(suppress=True)

config = tf.ConfigProto()
config.gpu_options.per_process_gpu_memory_fraction = 0.45
set_session(tf.Session(config=config))

voc_classes = ['Aeroplane', 'Bicycle', 'Bird', 'Boat', 'Bottle',
               'Bus', 'Car', 'Cat', 'Chair', 'Cow', 'Diningtable',
               'Dog', 'Horse','Motorbike', 'Person', 'Pottedplant',
               'Sheep', 'Sofa', 'Train', 'Tvmonitor']
NUM_CLASSES = len(voc_classes) + 1

input_shape=(300, 300, 3)
model = SSD300(input_shape, num_classes=NUM_CLASSES)
model.load_weights('weights_SSD300.hdf5', by_name=True)
bbox_util = BBoxUtility(NUM_CLASSES)

inputs = []
images = []
img_path = './pics/P_20171128_075219_vHDR_On.jpg'
img = image.load_img(img_path, target_size=(300, 300))
img = image.img_to_array(img)
images.append(imread(img_path))
inputs.append(img.copy())
inputs = preprocess_input(np.array(inputs))

preds = model.predict(inputs, batch_size=1, verbose=1)
results = bbox_util.detection_out(preds)

print(results)

for i, img in enumerate(images):
    # Parse the outputs.
    det_label = results[i][:, 0]
    det_conf = results[i][:, 1]
    det_xmin = results[i][:, 2]
    det_ymin = results[i][:, 3]
    det_xmax = results[i][:, 4]
    det_ymax = results[i][:, 5]

    # Get detections with confidence higher than 0.6.
    top_indices = [i for i, conf in enumerate(det_conf) if conf >= 0.6]

    top_conf = det_conf[top_indices]
    top_label_indices = det_label[top_indices].tolist()
    top_xmin = det_xmin[top_indices]
    top_ymin = det_ymin[top_indices]
    top_xmax = det_xmax[top_indices]
    top_ymax = det_ymax[top_indices]

    colors = plt.cm.hsv(np.linspace(0, 1, 21)).tolist()

    plt.imshow(img / 255.)
    currentAxis = plt.gca()

    for i in range(top_conf.shape[0]):
        xmin = int(round(top_xmin[i] * img.shape[1]))
        ymin = int(round(top_ymin[i] * img.shape[0]))
        xmax = int(round(top_xmax[i] * img.shape[1]))
        ymax = int(round(top_ymax[i] * img.shape[0]))
        score = top_conf[i]
        label = int(top_label_indices[i])
        label_name = voc_classes[label - 1]
        display_txt = '{:0.2f}, {}'.format(score, label_name)
        coords = (xmin, ymin), xmax-xmin+1, ymax-ymin+1
        color = colors[label]
        currentAxis.add_patch(plt.Rectangle(*coords, fill=False, edgecolor=color, linewidth=2))
        currentAxis.text(xmin, ymin, display_txt, bbox={'facecolor':color, 'alpha':0.5})

    plt.show()
```

# keras2での修正
keras2では、ssd_layer.pyのget_output_shape_forメソッドでエラーになるため、
メソッド名をcompute_output_shapeに変更します

参照　https://github.com/rykov8/ssd_keras/issues/60

```lang:python
#def get_output_shape_for(self, input_shape):
def compute_output_shape(self, input_shape):
```