This is the code I used to generate CSV file for all images.
"""Generate data.csv from data folder in working directory. """
from cv2 import imread,cvtColor,COLOR_RGB2GRAY,resize
from os import listdir
from numpy import array,savetxt,hstack
data=[]
for c in listdir('data'):
i = listdir('data').index(c)
print('Reading',c)
for sample in listdir('data/'+c):
path = 'data/' + c + '/' + sample
img = imread(path)
#img = cvtColor(img,COLOR_RGB2GRAY)
img = resize(img,(150,150))
row = hstack([img.ravel(),i])
data.append(row)
data = array(data)
savetxt('data.csv',data,delimiter=',',fmt='%i')
i recover this data using
print('Reading data...')
data = genfromtxt('data.csv',delimiter=',')
X = reshape(data[:,:-1],(data.shape[0],150,150,3))
y = data[:,-1]
print('Data: ',X.shape)
when i use imshow function on this data, it shows white box with some random colored pixels, but when i save this with imsave it saves a normal image.
Why it appeared different for imshow?
I imported numpy, opencv and os for these scripts.
Since no one answered it so far, imshow from OpenCV displays numpy arrays of dtype=int and of shape (h,w,3) with values between 0 and 255 or dtype=float and values between 0 and 1 and shape (h,w,3). If image is shown as white and some random pixel it could be because of values in range (0,255) but of dtype=float or anything else.
Like suggested by @Miki, changing dtype to uint should solve the problem too.