im.getdata()

Googling "PIL Handbook" yields this page

and, as I said,
"""


getdata

*im.getdata()* =sequence

Returns the contents of an image as a sequence object containing pixel
values. The sequence object is flattened, so that values for line one
follow directly after the values of line zero, and so on.

Note that the sequence object returned by this method is an internal PIL
data type, which only supports certain sequence operations, including
iteration and basic sequence access. To convert it to an ordinary
sequence (e.g. for printing), use *list(im.getdata())*.





How do I find out how the list look like?

Is it list[x][y] ? or rather, how did you find out how this internal
data type look like?

how do I access it ?


Tutor maillist - Tutor (AT) python (DOT) org

"elis aeris" <hunter92383 (AT) gmail (DOT) comwrote

*im.getdata()* =sequence
>
Returns the contents of an image as a sequence object

Note that the sequence object returned by this method is an internal
PIL
data type, which only supports certain sequence operations,
including
iteration and basic sequence access.

How do I find out how the list look like?
>
Is it list[x][y] ?
or rather, how did you find out how this internal data type look
like?

I'm not sure why you care what it looks like internally, you can use
indexing to access the pixels and you can iterate over them.
What more do you need? The indexing will be one dimensional
since the help page told you that the data was flattened. Thus

123
456
789

becomes

123456789

But mostly you won't care because you can iterate over the list
using a standard for loop.

And as ever in Python the easiest way to find out how things work
is just to try it in the interpreter. Use a small bitmap (16x16 say?)
and load it into a PIL image, use getdata and see what it looks like
when you index it, iterate over it and print it. Working with the
interpreter can eliminate most uncertainties when working with Python.

HTH,

--
Alan Gauld
Author of the Learn to Program web site




Tutor maillist - Tutor (AT) python (DOT) org

elis aeris schreef:
Googling "PIL Handbook" yields this page

<>
and, as I said,
"""


getdata

*im.getdata()* =sequence

If you're using PIL >= 1.1.6, there's also a pixel access object you can
use (the documentation is on that same page, in the 'load' section:

"(New in 1.1.6) In 1.1.6 and later, load returns a pixel access object
that can be used to read and modify pixels. The access object behaves
like a 2-dimensional array, so you can do:

pix = im.load()
print pix[x, y]
pix[x, y] = value

Access via this object is a lot faster than getpixel and putpixel."

Perhaps that's more useful to you?

A lot depends on exactly what you want to do with the pixel values. I
think you would do everyone (including yourself) a favor by just telling
us what you're going to do with the pixel values.

--
If I have been able to see further, it was only because I stood
on the shoulders of giants. -- Isaac Newton

Roel Schroeven


Tutor maillist - Tutor (AT) python (DOT) org

I am capturing a screen shot, but then the image was already


image, how do I .load it ?

it's not image.load()




import time
import ImageGrab # Part of PIL
from ctypes import *

class RECT(Structure):
_fields_ = [
('left', c_ulong),
('top', c_ulong),
('right', c_ulong),
('bottom', c_ulong)
]


GetForegroundWindow =
GetWindowRect = windll.user32.GetWindowRect


rect = RECT()
foreground_window = GetForegroundWindow()
GetWindowRect(foreground_window, byref(rect))
image = ImageGrab.grab((rect.left, rect.top, rect.right, rect.bottom))



print time.time()

pix = image.load()
print pix[x, y]

x = 0
y = 0
for x in xrange(1,1024,1):
for y in xrange(1,768,1):
print pix[10,10]


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elis aeris schreef:


I am capturing a screen shot, but then the image was already


image, how do I .load it ?

it's not image.load()

I see. In that case, you can't use the method I described; that only
works if you load the image from disk (as far as I know). I think you'd
better use getdata() as Alan described.

Something like this, if you need to access the pixels column-by-column
(Is that really what you want? You still haven't told us):

#
image = ImageGrab.grab ((rect.left, rect.top, rect.right, rect.bottom))
pixels = image.getdata()
for x in xrange(0, 1024):
for y in xrange(0, 768):
print pixels[x + y * 768]

Note: pixel indices start from 0, not from 1.

If you want to access them row-by-row (as is generally more often the
case) and you don't have a special need to have the x and y available:

image = ImageGrab.grab ((rect.left, rect.top, rect.right, rect.bottom))
for pixel in image.getdata():
print pixel


Anyway, you're printing a lot of pixels (786432 actually) is that
really what you want?


--
If I have been able to see further, it was only because I stood
on the shoulders of giants. -- Isaac Newton

Roel Schroeven


Tutor maillist - Tutor (AT) python (DOT) org

I am having a similar problem. I need to iterate over all the pixels in the image in order to modify them. How do I get the range in order to do a for loop over them. I hope this thread is still active.