How to read the RGB value of a given pixel in Python

Question

If I open an image with open  image jpg    how can I get the RGB values of a pixel assuming I have the coordinates of the pixel   Then  how can I do the reverse of this  Starting with a blank graphic   write  a pixel with a certain RGB value   I would prefer if I didn t have to download any additional libraries

User · Answer

As Dave Webb said      Here is my working code snippet printing the pixel colours from an   image   import os  sys import Image  im   Image open  image jpg   x   3 y   4  pix   im load   print pix x y

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import matplotlib pyplot as plt import matplotlib image as mpimg  img mpimg imread  Cricket ACT official logo png   imgplot   plt imshow img

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photo   Image open  IN jpg    your image photo   photo convert  RGB    width   photo size 0   define W and H height   photo size 1   for y in range 0  height    each pixel has coordinates     row          for x in range 0  width            RGB   photo getpixel  x y           R G B   RGB   now you can use the RGB value

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install PIL using the command  sudo apt-get install python-imaging  and run the following program  It will print RGB values of the image  If the image is large redirect the output to a file using     later open the file to see RGB values  import PIL import Image FILENAME  fn gif   image can be in gif jpeg or png format  im Image open FILENAME  convert  RGB   pix im load   w im size 0  h im size 1  for i in range w     for j in range h       print pix i j

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Using a library called Pillow  you can make this into a function  for ease of use later in your program  and if you have to use it multiple times  The function simply takes in the path of an image and the coordinates of the pixel you want to  quot grab  quot  It opens the image  converts it to an RGB color space  and returns the R  G  and B of the requested pixel  from PIL import Image def rgb of pixel img path  x  y       im   Image open img path  convert  RGB       r  g  b   im getpixel  x  y       a    r  g  b      return a    Note  I was not the original author of this code  it was left without an explanation  As it is fairly easy to explain  I am simply providing said explanation  just in case someone down the line does not understand it

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There s a really good article on wiki wxpython org entitled Working With Images  The article mentions the possiblity of using wxWidgets  wxImage   PIL or PythonMagick  Personally  I ve used PIL and wxWidgets and both make image manipulation fairly easy

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You can use pygame s surfarray module  This module has a 3d pixel array returning method called pixels3d surface   I ve shown usage below   from pygame import surfarray  image  display import pygame import numpy  important to import  pygame init   image   image load  myimagefile jpg    surface to render resolution    image get width   image get height    screen   display set mode resolution   create space for display screen blit image   0 0    superpose image on screen display flip   surfarray use arraytype  numpy    important  screenpix   surfarray pixels3d image   pixels in 3d array    x  y  rgb  for y in range resolution 1        for x in range resolution 0            for color in range 3               screenpix x  y  color     128              reverting colors screen blit surfarray make surface screenpix    0 0    superpose on screen display flip    update display while 1      print finished   I hope been helpful  Last word  screen is locked for lifetime of screenpix

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PyPNG - lightweight PNG decoder encoder  Although the question hints at JPG  I hope my answer will be useful to some people   Here s how to read and write PNG pixels using PyPNG module   import png  array  point    2  10    coordinates of pixel to be painted red  reader   png Reader filename  image png   w  h  pixels  metadata   reader read flat   pixel byte width   4 if metadata  alpha   else 3 pixel position   point 0    point 1    w new pixel value    255  0  0  0  if metadata  alpha   else  255  0  0  pixels    pixel position   pixel byte width      pixel position   1    pixel byte width    array array  B   new pixel value   output   open  image-with-red-dot png    wb   writer   png Writer w  h    metadata  writer write array output  pixels  output close     PyPNG is a single pure Python module less than 4000 lines long  including tests and comments   PIL is a more comprehensive imaging library  but it s also significantly heavier

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If you are looking to have three digits in the form of an RGB colour code  the following code should do just that   i   Image open path  pixels   i load     this is not a list  nor is it list   able width  height   i size  all pixels      for x in range width       for y in range height           cpixel   pixels x  y          all pixels append cpixel    This may work for you

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You could use the Tkinter module  which is the standard Python interface to the Tk GUI toolkit and you don t need extra download  See https   docs python org 2 library tkinter html    For Python 3  Tkinter is renamed to tkinter   Here is how to set RGB values    from http   tkinter unpythonic net wiki PhotoImage from Tkinter import    root   Tk    def pixel image  pos  color          Place pixel at pos  x y  on image  with color  r g b          r g b   color     x y   pos     image put    02x 02x 02x     r g b    y  x    photo   PhotoImage width 32  height 32   pixel photo   16 16    255 0 0      One lone pixel in the middle     label   Label root  image photo  label grid   root mainloop     And get RGB    from http   www kosbie net cmu spring-14 15-112 handouts steganographyEncoder py def getRGB image  x  y       value   image get x  y      return tuple map int  value split

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It s probably best to use the Python Image Library to do this which I m afraid is a separate download   The easiest way to do what you want is via the load   method on the Image object which returns a pixel access object which you can manipulate like an array   from PIL import Image  im   Image open  dead parrot jpg     Can be many different formats  pix   im load   print im size    Get the width and hight of the image for iterating over print pix x y     Get the RGBA Value of the a pixel of an image pix x y    value    Set the RGBA Value of the image  tuple  im save  alive parrot png      Save the modified pixels as  png   Alternatively  look at ImageDraw which gives a much richer API for creating images

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Image manipulation is a complex topic  and it s best if you do use a library  I can recommend gdmodule which provides easy access to many different image formats from within Python

User · Answer

Using Pillow  which works with Python 3 X as well as Python 2 7    you can do the following  from PIL import Image im   Image open  image jpg    r   width  height   im size pixel values   list im getdata     Now you have all pixel values  If it is RGB or another mode can be read by im mode  Then you can get pixel  x  y  by  pixel values width y x   Alternatively  you can use Numpy and reshape the array   gt  gt  gt  pixel values   numpy array pixel values  reshape  width  height  3    gt  gt  gt  x  y   0  1  gt  gt  gt  pixel values x  y    18  18  12   A complete  simple to use solution is   Third party modules import numpy from PIL import Image   def get image image path        quot  quot  quot Get a numpy array of an image so that one can access values x  y   quot  quot  quot      image   Image open image path   quot r quot       width  height   image size     pixel values   list image getdata        if image mode     quot RGB quot           channels   3     elif image mode     quot L quot           channels   1     else          print  quot Unknown mode   s quot    image mode          return None     pixel values   numpy array pixel values  reshape  width  height  channels       return pixel values   image   get image  quot gradient png quot    print image 0   print image shape   Smoke testing the code You might be uncertain about the order of width   height   channel  For this reason I ve created this gradient   The image has a width of 100px and a height of 26px  It has a color gradient going from  ffaa00  yellow  to  ffffff  white   The output is    255 172   5    255 172   5    255 172   5    255 171   5    255 172   5    255 172   5    255 171   5    255 171   5    255 171   5    255 172   5    255 172   5    255 171   5    255 171   5    255 172   5    255 172   5    255 172   5    255 171   5    255 172   5    255 172   5    255 171   5    255 171   5    255 172   4    255 172   5    255 171   5    255 171   5    255 172   5    100  26  3   Things to note   The shape is  width  height  channels  The image 0   hence the first row  has 26 triples of the same color

[python] How to read the RGB value of a given pixel in Python?

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