CODEWITHSUNDEEP
pythonopencvimage-loading
Agam
Agam

Reputation: 3

Unable to load image using imread()

I am not sure of why this is happening but I am not able to load image using imread(). I am able to open that image in paint and after saving that image, the image is being loaded and displayed. I am using Jupyter notebook.

import os
import cv2
import numpy as np
from matplotlib import pyplot as plt
%matplotlib inline

def displayImage(image):
 plt.imshow(image)
 plt.show()

image = cv2.imread('path/to/image')
displayImage(image)

Output

Output

Expected Output:

Expected Output

Upvotes: 0

Views: 3074

Answers (4)

Salman
Salman

Reputation: 1006

It happens because your image is in RGBA mode (your background is transparent). so you need to read your image in RGBA mode as: 

image = cv2.imread('path/to/image.png',-1)

or:

from scipy.ndimage import imread
rgba = imread('path/to/image.png', mode='RGBA')

the result:

enter image description here

Upvotes: 4

Mark Setchell
Mark Setchell

Reputation: 207853

The issue is that your image doesn't contain any non-zero Red, Green or Blue pixels, it is entirely black. The only reason it looks how you show it with "@ @ 6 L" is because it has a an alpha/transparency channel that masks the black out and reveals the white PNG background colour.

If you look at it with ImageMagick's identify you will see:

identify -verbose a.png | more
Image: a.png
  Format: PNG (Portable Network Graphics)
  Mime type: image/png
  Class: DirectClass
  Geometry: 203x50+0+0
  Resolution: 37.79x37.79
  Print size: 5.37179x1.3231
  Units: PixelsPerCentimeter
  Colorspace: sRGB
  Type: Bilevel
  Base type: Undefined
  Endianess: Undefined
  Depth: 8-bit
  Channel depth:
    Red: 1-bit
    Green: 1-bit
    Blue: 1-bit
    Alpha: 8-bit
  Channel statistics:
    Pixels: 10150
    Red:
      min: 0  (0)
      max: 0 (0)                 <--- Brightest Red is zero
      mean: 0 (0)
      standard deviation: 0 (0)
      kurtosis: -3
      skewness: 0
      entropy: 0
    Green:
      min: 0  (0)
      max: 0 (0)                 <--- Brightest Green is zero
      mean: 0 (0)
      standard deviation: 0 (0)
      kurtosis: -3
      skewness: 0
      entropy: 0
    Blue:
      min: 0  (0)
      max: 0 (0)                  <--- Brightest Blue is zero
      mean: 0 (0)
      standard deviation: 0 (0)
      kurtosis: -3
      skewness: 0
      entropy: 0
    Alpha:
      min: 0  (0)
      max: 255 (1)                         <--- Alpha channel is only one with info
      mean: 16.477 (0.0646159)
      standard deviation: 58.73 (0.230314)
      kurtosis: 10.7342
      skewness: 3.50997
      entropy: 0.128008
   ...
   ...
   Background color: white       <--- Background is white
   ...
   ...

The answer is to read ALL FOUR channels with cv2.IMREAD_UNCHANGED, and just use the 4th/alpha channel:

def read_transparent_png(filename):
image_4channel = cv2.imread(filename, cv2.IMREAD_UNCHANGED)
alpha_channel = image_4channel[:,:,3]
rgb_channels = image_4channel[:,:,:3]

Code extracted from here.

Upvotes: 1

davdsb
davdsb

Reputation: 131

After loading the image use that:

image = cv2.cvtColor(image, cv2.COLOR_BGR2RGB)

Upvotes: 0

Martin Beckett
Martin Beckett

Reputation: 96167

andCheck what data is actually being loaded. Check the size with image.shape(), either look at the max/min/mean values or if you use spyder (highly recommended), look at the data in the variables viewer.

ps. for a single display item there is no need for the plt.show() command

Upvotes: 0

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