Tensorflow Serving: InvalidArgumentError: Expected image (JPEG, PNG, or GIF), got unknown format starting with 'AAAAAAAAAAAAAAAA'

问题

I'm trying to prepare my custom Keras model for deploy to be used with Tensorflow Serving, but I'm running into issues with preprocessing my images.

When i train my model i use the following functions to preprocess my images:

def process_image_from_tf_example(self, image_str_tensor, n_channels=3):
    image = tf.image.decode_image(image_str_tensor)
    image.set_shape([256, 256, n_channels])
    image = tf.cast(image, tf.float32) / 255.0
    return image

def read_and_decode(self, serialized):
    parsed_example = tf.parse_single_example(serialized=serialized, features=self.features)
    input_image = self.process_image_from_tf_example(parsed_example["image_raw"], 3)
    ground_truth_image = self.process_image_from_tf_example(parsed_example["gt_image_raw"], 1)
    return input_image, ground_truth_image

My images are PNGs saved locally, and when i write them on the .tfrecord files i use tf.gfile.GFile(str(image_path), 'rb').read()

This works, I'm able to train my model and use it for local predictions.

Now I want to deploy my model to be used with Tensorflow Serving. My serving_input_receiver_fn function looks like this:

def serving_input_receiver_fn(self):
    input_ph = tf.placeholder(dtype=tf.string, shape=[None], name='image_bytes')
    images_tensor = tf.map_fn(self.process_image_from_tf_example, input_ph, back_prop=False, dtype=tf.float32)
    return tf.estimator.export.ServingInputReceiver({'input_1': images_tensor}, {'image_bytes': input_ph})

where process_image_from_tf_example is the same function as above, but i get the following error:

InvalidArgumentError (see above for traceback): assertion failed: [Unable to decode bytes as JPEG, PNG, GIF, or BMP]

Reading here it looks like this error is due to the fact that i'm not using tf.gfile.GFile(str(image_path), 'rb').read()

as with my training/test files, but i can't use it because i need to send encoded bytes formatted as

{"image_bytes": {'b64': base64.b64encode(image).decode()}}

as requested by TF Serving.

Examples online send JPEG encoded bytes and preprocess the image starting with

tf.image.decode_jpeg(image_buffer, channels=3)

but if i use a different preprocessing function in my serving_input_receiver_fn (different than the one used for training) that starts with

tf.image.decode_png(image_buffer, channels=3)

i get the following error:

InvalidArgumentError (see above for traceback): Expected image (JPEG, PNG, or GIF), got unknown format starting with 'AAAAAAAAAAAAAAAA'

(the same happens with decode_jpeg, by the way)

What am i doing wrong? Do you need more code from me to answer? Thanks a lot!

Edit!! Changed the title because it was not clear enough

回答1:

OK I solved it.

image was a numpy array but i had to do the following:

buffer = cv2.imencode('.jpg', image)[1].tostring()
bytes_image = base64.b64encode(buffer).decode('ascii')
{"image_bytes": {"b64": bytes_image}}

Also, my preprocessing and serving_input_receiver_fn functions changed:

def process_image_from_buffer(self, image_buffer):
    image = tf.image.decode_jpeg(image_buffer, channels=3)
    image = tf.image.convert_image_dtype(image, dtype=tf.float32)
    image = tf.expand_dims(image, 0)
    image = tf.image.resize_bilinear(image, [256, 256], align_corners=False)
    image = tf.squeeze(image, [0])
    image = tf.cast(image, tf.float32) / 255.0
    return image

def serving_input_receiver_fn(self):
    input_ph = tf.placeholder(dtype=tf.string, shape=[None])
    images_tensor = tf.map_fn(self.process_image_from_buffer, input_ph, back_prop=False, dtype=tf.float32)
    return tf.estimator.export.ServingInputReceiver({'input_1': images_tensor}, {'image_bytes': input_ph})

process_image_from_buffer is different than process_image_from_tf_example used above for training. I also removed name='image_bytes' from input_ph above.

Hope it's clear enough to help someone else.

Excellent guide partially used for solving it

来源：https://stackoverflow.com/questions/56275522/tensorflow-serving-invalidargumenterror-expected-image-jpeg-png-or-gif-go

标签

tensorflow-serving