openai/pixel-cnn

how to understand the loss function corner case for 0 and 255

weixsong opened this issue · 3 comments

Hi,

In the loss function, the code give a special value to value 0 and 255:

    # log probability for edge case of 0 (before scaling)
    log_cdf_plus = plus_in - tf.nn.softplus(plus_in)
    # log probability for edge case of 255 (before scaling)
    log_one_minus_cdf_min = -tf.nn.softplus(min_in)

I could not understand these code, how could me understand it?

I think you should know the relationship between sigmoid and softplus.
image

@npuichigo , thanks very much. I got it.