How do I reshape array of images obtained from .h5 file in python?

Question

I'm new to python and I apologize in advance if my question seems trivial.

I have a .h5 file containing pairs of images in greyscale organized in match and non-match groups. For my final purpose I need to consider each pair of images as a single image of 2 channels (where each channel is in fact an image).

To use my data I proceed like this:

I read the .h5 file putting my data in numpy arrays (I read both groups match and non-match, both with shape (50000,4096)):

 with h5py.File('supervised_64x64.h5','r') as hf:
     match = hf.get('/match')
     non_match = hf.get('/non-match')
     np_m = np.asarray(match)
     np_nm = np.asarray(non_match)
     hf.close()

Then I try to reshape the arrays:

reshaped_data_m = np_m.reshape(250000,2,4096)

Now, if I reshape the arrays as (250000,2,4096) and then I try to show the corresponding images what I get is actually right. But I need to reshape the arrays as (25000,64,64,2) and when I try to do this I get all black images.

Can you help me? Thank you in advance!

To know how to help you, you need to provide a little bit more information about the images themselves. What format are they saved in? as a 1D array of 4096 numbers? — meetaig
– meetaig, Commented Sep 5, 2016 at 8:40
Sorry, I forgot to write that the images are saved in bmp and the arrays are 1D of 4096 float64 numbers. — Paola
– Paola, Commented Sep 5, 2016 at 8:58

Community · Accepted Answer · 2017-05-23 12:00:56Z

2

I bet you need to first transpose your input matrix from 250000x2x4096 to 250000x4096x2, after which you can do the reshape.

Luckly, numpy offers the transpose function which should do the trick. See this question for a bigger discussion around transposing.

In your particular case, the invocation would be:

transposed_data_m = numpy.transpose(np_m, [1, 3, 2])
reshaped_data_m = tranposed_data_m.reshape(250000, 64, 64, 2)

edited May 23, 2017 at 12:00

CommunityBot

11 silver badge

answered Sep 5, 2016 at 8:42

Horia Coman

8,8112 gold badges25 silver badges25 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

meetaig Over a year ago

nice, I did not even see that the 2 changed places. I think this might be the solution OP is looking for

Paola Over a year ago

Thank you for your suggestion! Unfortunately I keep getting black images.

Collectives™ on Stack Overflow

How do I reshape array of images obtained from .h5 file in python?

1 Answer 1

2 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related