CODEWITHSUNDEEP
pythontensorflowkerasrgb
atlas
atlas

Reputation: 411

Tensorflow image evaluation one on channel

I am using Keras with Tensorflow backend and want to evaluate the PSNR between two images. I am able to evaluate on all three RGB channels, like this: 

def psnr(hr, sr):
    return tf.image.psnr(hr, sr, max_val=255)

with the psnr function from tensorflow (tf.image.psnr

But what would I do to only evaluate on the first channel? I assume I need to extract those values from the tensor some how. In python it is usually possible to do something like hr[:, 0, 0], but this obviously does not work here.

Upvotes: 0

Views: 1657

Answers (1)

mujjiga
mujjiga

Reputation: 16906

im1 = tf.image.convert_image_dtype(np.random.randn(64,64,3), tf.float32)
im2 = tf.image.convert_image_dtype(np.random.randn(64,64,3), tf.float32)

psnr = tf.image.psnr(tf.expand_dims(im1[:,:,0], 2), 
                     tf.expand_dims(im2[:,:,0], 2), max_val=255)

with tf.Session() as sess:
    print (sess.run(psnr))

Get the first channel using im1[:,:,0] and reshape it to h x w x 1 by adding the one channel using expand_dims

Upvotes: 1

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