Returning Pixel Value as "None" - python

I have the following line of code:
img = cv.imread("c:/users/admin/downloads/sack.jpg", 1)
It is not reading anything into img. img is showing None. sack.jpg exists, and is an image file.

import os
import cv2
image_path = r"c:/users/admin/downloads/sack.jpg"
assert os.path.isfile(image_path)
img = cv2.imread(image_path, 1)
Either the assert will fail, or the read will succeed, or the file is not a valid image.
Notice the r preceding the path.
Also notice cv2, not cv.

EDITED
This worked for me on WINDOWS:
import cv2
path = r'c:/users/admin/downloads/sack.jpg'
img = cv2.imread(path)
cv2.imshow('imgTitle',img)
cv2.waitKey()
you can check how cv2.imread works here.
Note that:
It's (cv2) not cv.
Add cv.waitKey() so your image won't open and close very fast.
Anyway using the manual path writing is not very practical in the
real time applications, insted of that you can try using libraries
like os and pathlib, it's very recommended too.

Related

i save files(.jpg) in another folder and i want to use that files in my python program. how do i import them

I want to know how to import files.jpg in another folder to use in my program.
from myfolder import picture.jpg
import cv2
img = cv2.imread("picture.jpg", 1)
cv2.imshow("Image",img)
cv2.waitKey(0)
cv2.destroyAllWindows()
You only use import to interact with python modules (.py files).
To open an image you just use appropriate image path in cv.open
For example:
import cv2
img = cv2.imread("myfolder/picture.jpg", 1)
cv2.imshow("Image",img)
cv2.waitKey(0)
cv2.destroyAllWindows()
You do not need to import the .jpg file since it is not a python module. You can access the file directly from the cv2.imread() method by providing the absolute file path instead of just the name of the file.
For example, if picture.jpg was inside Documents/Project, then the code would be as follows:
img = cv2.imread("Documents/Project/picture.jpg", 1)
As for finding the absolute path of a file, the process is different for different operating systems. Here is how to find it on a mac, and here's the same for windows.
Hope this helps!

Python OpenCV imwrite 0 bytes image depends on execution dir

I have written a small script to convert a RGB image to grey.
When I run the script in terminal form current dir (python3 image.py), it works perfectly fine.
But when I rum it from a dir lower like python3 proc/image.py it creates a result image with 0 bytes size.
here is the code of image.py
import os
import numpy as np
import cv2
def sw(name):
dir_path = os.path.dirname(os.path.realpath(__file__))
img_path = os.path.join(dir_path, name)
print(img_path)
img = cv2.imread(name, 0)
rslt_path = os.path.join(dir_path, "schwarn_g.jpeg")
print(rslt_path)
cv2.imwrite(rslt_path, img)
return img
if __name__ == "__main__":
sw('schwarn.jpeg')
Can somebody explain this behavior?
Thanks a lot!
You are opening the image that you want to work on with the following line:
img = cv2.imread(name, 0)
And since your script always calls the function with this line:
sw('schwarn.jpeg')
you are always trying to open the img: schwarn.jpg from the same directory that you are running the script. All your os.path joining is affecting where the grayscale image is outputted to - not where the original image is read from.
This means that since the program is trying to open the img in the same directory that you are running the script, the img can only be loaded in when you are running the script in the same directory as the img. Therefore, when you try and run the script in a different directory, the img cannot be read in and the resulting greyscale image has no contents...

python reading a video

I am using Python 2.7.11 and OpenCV 2.4.9. I cannot read a video by using cv2.imread() or cv2.VideoCapture().
import cv2
cap = cv2.VideoCapture('cam.avi')
print ("open = ",cap.isOpened())
OR
import cv2
cap = cv2.imread('cam.avi')
print ("open = ",cap.isOpened())
It will return false.
I don't know why. I am sure that the cam.avi is here.
imread() does not support reading from video files directly.
See also the documentation of OpenCV.
If you want to read a video with imread you will first have to convert it to single images, either via a serperate program (ffmpeg comes to mind) or using OpenCV and store the images in memory.
Try providing full path to video, like:
import cv2
cap = cv2.VideoCapture(r'C:\Users\e01069\Downloads\drop.avi')
print ("open = ",cap.isOpened())
If you run following in your same file, you would know that python is looking for your file on some different location.
import os
print os.path.abspath(__file__) #this is your current working directory
Note: .imread wouldn't work this way.

Using python to save a JPG image that was edited in the script

Referring to the answer to this question, I tried to save my own JPG image files, after some basic image processing. I've only applied a rotation and a shear. This is my code:
import numpy as np
import sys
from skimage import data, io, filter, color, exposure
import skimage.transform as tf
from skimage.transform import rotate, setup, AffineTransform
from PIL import Image
mypath = PATH_TO_FILENAME
readfile = FILENAME
img = color.rgb2gray(io.imread(mypath + readfile))
myimg = rotate(img, angle=10, order=2)
afine_tf = tf.AffineTransform(shear=0.1)
editedimg = tf.warp(myimg, afine_tf)
# IF I UNCOMMENT THE TWO LINES BELOW, I CAN SEE THE EDITED IMAGE AS EXPECTED
#io.imshow(editedimg)
#io.show()
saveimg= np.array(editedimg)
result = Image.fromarray((saveimg).astype(np.uint8))
newfile = "edited_" + readfile
result.save(path+newfile)
I know that the image processing was fine because if I display it before saving, it's just the original image with a bit of rotation and shearing, as expected. But I'm doing something wrong while saving it. I tried without the astype(np.uint8)) part but got an error. Then I removed some of the code from the link mentioned above because I guessed it was particularly for Fourier Transforms, since when I included some of their code, then I got an image that was all gray but with white lines in the direction of the shear I'd applied. But now the image that gets saved is just 2KB of nothing but blackness.
And when I tried something as simple as:
result = Image.fromarray(editedimg)
result.save(path+newfile)
then I got this error:
raise IOError("cannot write mode %s as JPEG" % im.mode)
IOError: cannot write mode F as JPEG
I don't really need to use PIL, if there's another way to simply save my image, I'm fine with that.
Look into the PIL fork, Pillow, is is not as outdated and what you should probably be using for this.
Also depending on your operating system you may need a few other libraries to compile PIL with JPEG support properly, see here
This may also help Says you need to convert your image to RGB mode before saving.
Image.open('old.jpeg').convert('RGB').save('new.jpeg')

Programmatically generate video or animated GIF in Python?

I have a series of images that I want to create a video from. Ideally I could specify a frame duration for each frame but a fixed frame rate would be fine too. I'm doing this in wxPython, so I can render to a wxDC or I can save the images to files, like PNG. Is there a Python library that will allow me to create either a video (AVI, MPG, etc) or an animated GIF from these frames?
Edit: I've already tried PIL and it doesn't seem to work. Can someone correct me with this conclusion or suggest another toolkit? This link seems to backup my conclusion regarding PIL: http://www.somethinkodd.com/oddthinking/2005/12/06/python-imaging-library-pil-and-animated-gifs/
I'd recommend not using images2gif from visvis because it has problems with PIL/Pillow and is not actively maintained (I should know, because I am the author).
Instead, please use imageio, which was developed to solve this problem and more, and is intended to stay.
Quick and dirty solution:
import imageio
images = []
for filename in filenames:
images.append(imageio.imread(filename))
imageio.mimsave('/path/to/movie.gif', images)
For longer movies, use the streaming approach:
import imageio
with imageio.get_writer('/path/to/movie.gif', mode='I') as writer:
for filename in filenames:
image = imageio.imread(filename)
writer.append_data(image)
Here's how you do it using only PIL (install with: pip install Pillow):
import glob
import contextlib
from PIL import Image
# filepaths
fp_in = "/path/to/image_*.png"
fp_out = "/path/to/image.gif"
# use exit stack to automatically close opened images
with contextlib.ExitStack() as stack:
# lazily load images
imgs = (stack.enter_context(Image.open(f))
for f in sorted(glob.glob(fp_in)))
# extract first image from iterator
img = next(imgs)
# https://pillow.readthedocs.io/en/stable/handbook/image-file-formats.html#gif
img.save(fp=fp_out, format='GIF', append_images=imgs,
save_all=True, duration=200, loop=0)
See docs: https://pillow.readthedocs.io/en/stable/handbook/image-file-formats.html#gif
Well, now I'm using ImageMagick. I save my frames as PNG files and then invoke ImageMagick's convert.exe from Python to create an animated GIF. The nice thing about this approach is I can specify a frame duration for each frame individually. Unfortunately this depends on ImageMagick being installed on the machine. They have a Python wrapper but it looks pretty crappy and unsupported. Still open to other suggestions.
As of June 2009 the originally cited blog post has a method to create animated GIFs in the comments. Download the script images2gif.py (formerly images2gif.py, update courtesy of #geographika).
Then, to reverse the frames in a gif, for instance:
#!/usr/bin/env python
from PIL import Image, ImageSequence
import sys, os
filename = sys.argv[1]
im = Image.open(filename)
original_duration = im.info['duration']
frames = [frame.copy() for frame in ImageSequence.Iterator(im)]
frames.reverse()
from images2gif import writeGif
writeGif("reverse_" + os.path.basename(filename), frames, duration=original_duration/1000.0, dither=0)
I used images2gif.py which was easy to use. It did seem to double the file size though..
26 110kb PNG files, I expected 26*110kb = 2860kb, but my_gif.GIF was 5.7mb
Also because the GIF was 8bit, the nice png's became a little fuzzy in the GIF
Here is the code I used:
__author__ = 'Robert'
from images2gif import writeGif
from PIL import Image
import os
file_names = sorted((fn for fn in os.listdir('.') if fn.endswith('.png')))
#['animationframa.png', 'animationframb.png', 'animationframc.png', ...] "
images = [Image.open(fn) for fn in file_names]
print writeGif.__doc__
# writeGif(filename, images, duration=0.1, loops=0, dither=1)
# Write an animated gif from the specified images.
# images should be a list of numpy arrays of PIL images.
# Numpy images of type float should have pixels between 0 and 1.
# Numpy images of other types are expected to have values between 0 and 255.
#images.extend(reversed(images)) #infinit loop will go backwards and forwards.
filename = "my_gif.GIF"
writeGif(filename, images, duration=0.2)
#54 frames written
#
#Process finished with exit code 0
Here are 3 of the 26 frames:
shrinking the images reduced the size:
size = (150,150)
for im in images:
im.thumbnail(size, Image.ANTIALIAS)
To create a video, you could use opencv,
#load your frames
frames = ...
#create a video writer
writer = cvCreateVideoWriter(filename, -1, fps, frame_size, is_color=1)
#and write your frames in a loop if you want
cvWriteFrame(writer, frames[i])
I came across this post and none of the solutions worked, so here is my solution that does work
Problems with other solutions thus far:
1) No explicit solution as to how the duration is modified
2) No solution for the out of order directory iteration, which is essential for GIFs
3) No explanation of how to install imageio for python 3
install imageio like this: python3 -m pip install imageio
Note: you'll want to make sure your frames have some sort of index in the filename so they can be sorted, otherwise you'll have no way of knowing where the GIF starts or ends
import imageio
import os
path = '/Users/myusername/Desktop/Pics/' # on Mac: right click on a folder, hold down option, and click "copy as pathname"
image_folder = os.fsencode(path)
filenames = []
for file in os.listdir(image_folder):
filename = os.fsdecode(file)
if filename.endswith( ('.jpeg', '.png', '.gif') ):
filenames.append(filename)
filenames.sort() # this iteration technique has no built in order, so sort the frames
images = list(map(lambda filename: imageio.imread(filename), filenames))
imageio.mimsave(os.path.join('movie.gif'), images, duration = 0.04) # modify duration as needed
Like Warren said last year, this is an old question. Since people still seem to be viewing the page, I'd like to redirect them to a more modern solution. Like blakev said here, there is a Pillow example on github.
import ImageSequence
import Image
import gifmaker
sequence = []
im = Image.open(....)
# im is your original image
frames = [frame.copy() for frame in ImageSequence.Iterator(im)]
# write GIF animation
fp = open("out.gif", "wb")
gifmaker.makedelta(fp, frames)
fp.close()
Note: This example is outdated (gifmaker is not an importable module, only a script). Pillow has a GifImagePlugin (whose source is on GitHub), but the doc on ImageSequence seems to indicate limited support (reading only)
Old question, lots of good answers, but there might still be interest in another alternative...
The numpngw module that I recently put up on github (https://github.com/WarrenWeckesser/numpngw) can write animated PNG files from numpy arrays. (Update: numpngw is now on pypi: https://pypi.python.org/pypi/numpngw.)
For example, this script:
import numpy as np
import numpngw
img0 = np.zeros((64, 64, 3), dtype=np.uint8)
img0[:32, :32, :] = 255
img1 = np.zeros((64, 64, 3), dtype=np.uint8)
img1[32:, :32, 0] = 255
img2 = np.zeros((64, 64, 3), dtype=np.uint8)
img2[32:, 32:, 1] = 255
img3 = np.zeros((64, 64, 3), dtype=np.uint8)
img3[:32, 32:, 2] = 255
seq = [img0, img1, img2, img3]
for img in seq:
img[16:-16, 16:-16] = 127
img[0, :] = 127
img[-1, :] = 127
img[:, 0] = 127
img[:, -1] = 127
numpngw.write_apng('foo.png', seq, delay=250, use_palette=True)
creates:
You'll need a browser that supports animated PNG (either directly or with a plugin) to see the animation.
As one member mentioned above, imageio is a great way to do this. imageio also allows you to set the frame rate, and I actually wrote a function in Python that allows you to set a hold on the final frame. I use this function for scientific animations where looping is useful but immediate restart isn't. Here is the link and the function:
How to make a GIF using Python
import matplotlib.pyplot as plt
import os
import imageio
def gif_maker(gif_name,png_dir,gif_indx,num_gifs,dpi=90):
# make png path if it doesn't exist already
if not os.path.exists(png_dir):
os.makedirs(png_dir)
# save each .png for GIF
# lower dpi gives a smaller, grainier GIF; higher dpi gives larger, clearer GIF
plt.savefig(png_dir+'frame_'+str(gif_indx)+'_.png',dpi=dpi)
plt.close('all') # comment this out if you're just updating the x,y data
if gif_indx==num_gifs-1:
# sort the .png files based on index used above
images,image_file_names = [],[]
for file_name in os.listdir(png_dir):
if file_name.endswith('.png'):
image_file_names.append(file_name)
sorted_files = sorted(image_file_names, key=lambda y: int(y.split('_')[1]))
# define some GIF parameters
frame_length = 0.5 # seconds between frames
end_pause = 4 # seconds to stay on last frame
# loop through files, join them to image array, and write to GIF called 'wind_turbine_dist.gif'
for ii in range(0,len(sorted_files)):
file_path = os.path.join(png_dir, sorted_files[ii])
if ii==len(sorted_files)-1:
for jj in range(0,int(end_pause/frame_length)):
images.append(imageio.imread(file_path))
else:
images.append(imageio.imread(file_path))
# the duration is the time spent on each image (1/duration is frame rate)
imageio.mimsave(gif_name, images,'GIF',duration=frame_length)
It's not a python library, but mencoder can do that: Encoding from multiple input image files. You can execute mencoder from python like this:
import os
os.system("mencoder ...")
Installation
pip install imageio-ffmpeg
pip install imageio
Code
import imageio
images = []
for filename in filenames:
images.append(imageio.imread(filename))
imageio.mimsave('movie.mp4', images)
Quality is raised and size is reduced from 8Mb to 80Kb when saving as mp4 than gif
from PIL import Image
import glob #use it if you want to read all of the certain file type in the directory
imgs=[]
for i in range(596,691):
imgs.append("snap"+str(i)+'.png')
print("scanned the image identified with",i)
starting and ending value+1 of the index that identifies different file names
imgs = glob.glob("*.png") #do this if you want to read all files ending with .png
my files were: snap596.png, snap597.png ...... snap690.png
frames = []
for i in imgs:
new_frame = Image.open(i)
frames.append(new_frame)
Save into a GIF file that loops forever
frames[0].save('fire3_PIL.gif', format='GIF',
append_images=frames[1:],
save_all=True,
duration=300, loop=0)
I found flickering issue with imageio and this method fixed it.
Have you tried PyMedia? I am not 100% sure but it looks like this tutorial example targets your problem.
With windows7, python2.7, opencv 3.0, the following works for me:
import cv2
import os
vvw = cv2.VideoWriter('mymovie.avi',cv2.VideoWriter_fourcc('X','V','I','D'),24,(640,480))
frameslist = os.listdir('.\\frames')
howmanyframes = len(frameslist)
print('Frames count: '+str(howmanyframes)) #just for debugging
for i in range(0,howmanyframes):
print(i)
theframe = cv2.imread('.\\frames\\'+frameslist[i])
vvw.write(theframe)
The easiest thing that makes it work for me is calling a shell command in Python.
If your images are stored such as dummy_image_1.png, dummy_image_2.png ... dummy_image_N.png, then you can use the function:
import subprocess
def grid2gif(image_str, output_gif):
str1 = 'convert -delay 100 -loop 1 ' + image_str + ' ' + output_gif
subprocess.call(str1, shell=True)
Just execute:
grid2gif("dummy_image*.png", "my_output.gif")
This will construct your gif file my_output.gif.
The task can be completed by running the two line python script from the same folder as the sequence of picture files. For png formatted files the script is -
from scitools.std import movie
movie('*.png',fps=1,output_file='thisismygif.gif')
I was looking for a single line code and found the following to work for my application. Here is what I did:
First Step: Install ImageMagick from the link below
https://www.imagemagick.org/script/download.php
Second Step: Point the cmd line to the folder where the images (in my case .png format) are placed
Third Step: Type the following command
magick -quality 100 *.png outvideo.mpeg
Thanks FogleBird for the idea!
Addition to Smart Manoj answers: Make a .mp4 movie from all images in a folder
Installation:
pip install imageio-ffmpeg
pip install imageio
Code:
import os
import imageio
root = r'path_to_folder_with_images'
images = []
for subdir, dirs, files in os.walk(root):
for file in files:
images.append(imageio.imread(os.path.join(root,file)))
savepath = r'path_to_save_folder'
imageio.mimsave(os.path.join(savepath,'movie.mp4'), images)
PS: Make sure your "files" list is sorted the way you want, you will save some time if you already save your images accordingly
A simple function that makes GIFs:
import imageio
import pathlib
from datetime import datetime
def make_gif(image_directory: pathlib.Path, frames_per_second: float, **kwargs):
"""
Makes a .gif which shows many images at a given frame rate.
All images should be in order (don't know how this works) in the image directory
Only tested with .png images but may work with others.
:param image_directory:
:type image_directory: pathlib.Path
:param frames_per_second:
:type frames_per_second: float
:param kwargs: image_type='png' or other
:return: nothing
"""
assert isinstance(image_directory, pathlib.Path), "input must be a pathlib object"
image_type = kwargs.get('type', 'png')
timestampStr = datetime.now().strftime("%y%m%d_%H%M%S")
gif_dir = image_directory.joinpath(timestampStr + "_GIF.gif")
print('Started making GIF')
print('Please wait... ')
images = []
for file_name in image_directory.glob('*.' + image_type):
images.append(imageio.imread(image_directory.joinpath(file_name)))
imageio.mimsave(gif_dir.as_posix(), images, fps=frames_per_second)
print('Finished making GIF!')
print('GIF can be found at: ' + gif_dir.as_posix())
def main():
fps = 2
png_dir = pathlib.Path('C:/temp/my_images')
make_gif(png_dir, fps)
if __name__ == "__main__":
main()
I just tried the following and was very useful:
First Download the libraries Figtodat and images2gif to your local directory.
Secondly Collect the figures in an array and convert them to an animated gif:
import sys
sys.path.insert(0,"/path/to/your/local/directory")
import Figtodat
from images2gif import writeGif
import matplotlib.pyplot as plt
import numpy
figure = plt.figure()
plot = figure.add_subplot (111)
plot.hold(False)
# draw a cardinal sine plot
images=[]
y = numpy.random.randn(100,5)
for i in range(y.shape[1]):
plot.plot (numpy.sin(y[:,i]))
plot.set_ylim(-3.0,3)
plot.text(90,-2.5,str(i))
im = Figtodat.fig2img(figure)
images.append(im)
writeGif("images.gif",images,duration=0.3,dither=0)
I came upon PIL's ImageSequence module, which offers for a better (and more standard) GIF aninmation. I also use Tk's after() method this time, which is better than time.sleep().
from Tkinter import *
from PIL import Image, ImageTk, ImageSequence
def stop(event):
global play
play = False
exit()
root = Tk()
root.bind("<Key>", stop) # Press any key to stop
GIFfile = {path_to_your_GIF_file}
im = Image.open(GIFfile); img = ImageTk.PhotoImage(im)
delay = im.info['duration'] # Delay used in the GIF file
lbl = Label(image=img); lbl.pack() # Create a label where to display images
play = True;
while play:
for frame in ImageSequence.Iterator(im):
if not play: break
root.after(delay);
img = ImageTk.PhotoImage(frame)
lbl.config(image=img); root.update() # Show the new frame/image
root.mainloop()
It's really incredible ... All are proposing some special package for playing an animated GIF, at the moment that it can be done with Tkinter and the classic PIL module!
Here is my own GIF animation method (I created a while ago). Very simple:
from Tkinter import *
from PIL import Image, ImageTk
from time import sleep
def stop(event):
global play
play = False
exit()
root = Tk()
root.bind("<Key>", stop) # Press any key to stop
GIFfile = {path_to_your_GIF_file}
im = Image.open(GIFfile); img = ImageTk.PhotoImage(im)
delay = float(im.info['duration'])/1000; # Delay used in the GIF file
lbl = Label(image=img); lbl.pack() # Create a label where to display images
play = True; frame = 0
while play:
sleep(delay);
frame += 1
try:
im.seek(frame); img = ImageTk.PhotoImage(im)
lbl.config(image=img); root.update() # Show the new frame/image
except EOFError:
frame = 0 # Restart
root.mainloop()
You can set your own means to stop the animation. Let me know if you like to get the full version with play/pause/quit buttons.
Note: I am not sure if the consecutive frames are read from memory or from the file (disk). In the second case it would be more efficient if they all read at once and saved into an array (list). (I'm not so interested to find out! :)
I understand you asked about converting images to a gif; however, if the original format is MP4, you could use FFmpeg:
ffmpeg -i input.mp4 output.gif

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