I have a small problem how to convert an image from matplotlib to PIL
right now doing somthing like this:
------------------------------------------
from scipy import *
from pylab import *
from PIL import Image
a = arange(16384).reshape(128,128)
imsave( "test.png", a, cmap=cm.summer,vmin=0,vmax=16383)
b = Image.open("test.png" )
------------------------------------------
so I have a 128x128 array, get a 128x128 size png by making use of a
colormap and get a 128x128 size PIL image. But so far I could figure out a
way to do this directly without writing a temporary png and reading it
again, which is quite slow. My important point here is to keep the the pixel
resolution.
I would be glad about some help
Regards Hans
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On 31 May 2010 19:49, rugspin <pie...@we...> wrote:
>
> I have a small problem how to convert an image from matplotlib to PIL
>
> right now doing somthing like this:
> ------------------------------------------
> from scipy import *
> from pylab import *
> from PIL import Image
>
> a = arange(16384).reshape(128,128)
> imsave( "test.png", a, cmap=cm.summer,vmin=0,vmax=16383)
> b = Image.open("test.png" )
> ------------------------------------------
>
The Image.fromarray function should do what you want. For example,
import numpy as np # note: use of "from foo import *"
import Image # is discouraged where possible
a = np.arange(128)[None,:] * np.ones(128)[:,None]
b = Image.fromarray(a)
c = np.asarray(b)
np.all(c == a)
-> True
I hope that helps,
Angus.
--
AJC McMorland
Post-doctoral research fellow
Neurobiology, University of Pittsburgh
On 31 May 2010 23:17, Angus McMorland <am...@gm...> wrote:
> On 31 May 2010 19:49, rugspin <pie...@we...> wrote:
>
>>
>> I have a small problem how to convert an image from matplotlib to PIL
>>
>> right now doing somthing like this:
>> ------------------------------------------
>> from scipy import *
>> from pylab import *
>> from PIL import Image
>>
>> a = arange(16384).reshape(128,128)
>> imsave( "test.png", a, cmap=cm.summer,vmin=0,vmax=16383)
>> b = Image.open("test.png" )
>> ------------------------------------------
>>
>
> The Image.fromarray function should do what you want. For example,
>
> import numpy as np # note: use of "from foo import *"
> import Image # is discouraged where possible
>
> a = np.arange(128)[None,:] * np.ones(128)[:,None]
>
Sorry - I was playing around with a few iterations of this line, and didn't
provide the most useful one. Your example:
a = np.arange(128**2).reshape(128,128)
should also work fine.
> b = Image.fromarray(a)
> c = np.asarray(b)
> np.all(c == a)
> -> True
>
> I hope that helps,
>
> Angus.
>
--
AJC McMorland
Post-doctoral research fellow
Neurobiology, University of Pittsburgh
Angus McMorland-2 wrote:
>
> On 31 May 2010 23:17, Angus McMorland <am...@gm...> wrote:
>
>> On 31 May 2010 19:49, rugspin <pie...@we...> wrote:
>>
>>>
>>> I have a small problem how to convert an image from matplotlib to PIL
>>>
>>> right now doing somthing like this:
>>> ------------------------------------------
>>> from scipy import *
>>> from pylab import *
>>> from PIL import Image
>>>
>>> a = arange(16384).reshape(128,128)
>>> imsave( "test.png", a, cmap=cm.summer,vmin=0,vmax=16383)
>>> b = Image.open("test.png" )
>>> ------------------------------------------
>>>
>>
>> The Image.fromarray function should do what you want. For example,
>>
>> import numpy as np # note: use of "from foo import *"
>> import Image # is discouraged where possible
>>
>> a = np.arange(128)[None,:] * np.ones(128)[:,None]
>>
>
> Sorry - I was playing around with a few iterations of this line, and
> didn't
> provide the most useful one. Your example:
>
> a = np.arange(128**2).reshape(128,128)
>
> should also work fine.
>
>
>> b = Image.fromarray(a)
>> c = np.asarray(b)
>> np.all(c == a)
>> -> True
>>
>> I hope that helps,
>>
>> Angus.
>>
>
> --
> AJC McMorland
> Post-doctoral research fellow
> Neurobiology, University of Pittsburgh
>
> ------------------------------------------------------------------------------
>
>
> _______________________________________________
> Matplotlib-users mailing list
> Mat...@li...
> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>
>
Thank you Angus
but that's not exactly what i was looking for. The fromarray function is
very basic, so I would have to take care of all the RGBA of the array. the
imshow and imsave functions take care of all that for example adding a
colormap. After choosing a reasonable colormap (vmin, vmax, ....) I would
like to convert this into a PIL image.
Best Regard
Hans
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You may use StringIO.
from scipy import *
from pylab import *
from PIL import Image
import cStringIO
a = arange(16384).reshape(128,128)
f = cStringIO.StringIO()
imsave(f, a, cmap=cm.summer,vmin=0,vmax=16383, format="png") # you'd
better set the format explicitly.
f.reset()
b = Image.open(f)
f.close()
IHTH,
-JJ
On Tue, Jun 1, 2010 at 5:18 AM, rugspin <pie...@we...> wrote:
>
>
>
> Angus McMorland-2 wrote:
>>
>> On 31 May 2010 23:17, Angus McMorland <am...@gm...> wrote:
>>
>>> On 31 May 2010 19:49, rugspin <pie...@we...> wrote:
>>>
>>>>
>>>> I have a small problem how to convert an image from matplotlib to PIL
>>>>
>>>> right now doing somthing like this:
>>>> ------------------------------------------
>>>> from scipy import *
>>>> from pylab import *
>>>> from PIL import Image
>>>>
>>>> a = arange(16384).reshape(128,128)
>>>> imsave( "test.png", a, cmap=cm.summer,vmin=0,vmax=16383)
>>>> b = Image.open("test.png" )
>>>> ------------------------------------------
>>>>
>>>
>>> The Image.fromarray function should do what you want. For example,
>>>
>>> import numpy as np # note: use of "from foo import *"
>>> import Image # is discouraged where possible
>>>
>>> a = np.arange(128)[None,:] * np.ones(128)[:,None]
>>>
>>
>> Sorry - I was playing around with a few iterations of this line, and
>> didn't
>> provide the most useful one. Your example:
>>
>> a = np.arange(128**2).reshape(128,128)
>>
>> should also work fine.
>>
>>
>>> b = Image.fromarray(a)
>>> c = np.asarray(b)
>>> np.all(c == a)
>>> -> True
>>>
>>> I hope that helps,
>>>
>>> Angus.
>>>
>>
>> --
>> AJC McMorland
>> Post-doctoral research fellow
>> Neurobiology, University of Pittsburgh
>>
>> ------------------------------------------------------------------------------
>>
>>
>> _______________________________________________
>> Matplotlib-users mailing list
>> Mat...@li...
>> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>>
>>
>
> Thank you Angus
> but that's not exactly what i was looking for. The fromarray function is
> very basic, so I would have to take care of all the RGBA of the array. the
> imshow and imsave functions take care of all that for example adding a
> colormap. After choosing a reasonable colormap (vmin, vmax, ....) I would
> like to convert this into a PIL image.
>
> Best Regard
> Hans
>
> --
> View this message in context: http://old.nabble.com/imshow%2C-imsave-to-PIL-image-conversion-tp28736246p28739401.html
> Sent from the matplotlib - users mailing list archive at Nabble.com.
>
>
> ------------------------------------------------------------------------------
>
> _______________________________________________
> Matplotlib-users mailing list
> Mat...@li...
> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>
Thanks Jae-Joo
That's doing it, thought there might be an internal way within matplotlib,
but I could figure one.
I'm quite confused with the canvas, dpi, ...
Regards Hans
Jae-Joon Lee wrote:
>
> You may use StringIO.
>
> from scipy import *
> from pylab import *
> from PIL import Image
>
> import cStringIO
>
>
> a = arange(16384).reshape(128,128)
>
> f = cStringIO.StringIO()
> imsave(f, a, cmap=cm.summer,vmin=0,vmax=16383, format="png") # you'd
> better set the format explicitly.
> f.reset()
> b = Image.open(f)
> f.close()
>
> IHTH,
>
> -JJ
>
>
> On Tue, Jun 1, 2010 at 5:18 AM, rugspin <pie...@we...> wrote:
>>
>>
>>
>> Angus McMorland-2 wrote:
>>>
>>> On 31 May 2010 23:17, Angus McMorland <am...@gm...> wrote:
>>>
>>>> On 31 May 2010 19:49, rugspin <pie...@we...> wrote:
>>>>
>>>>>
>>>>> I have a small problem how to convert an image from matplotlib to PIL
>>>>>
>>>>> right now doing somthing like this:
>>>>> ------------------------------------------
>>>>> from scipy import *
>>>>> from pylab import *
>>>>> from PIL import Image
>>>>>
>>>>> a = arange(16384).reshape(128,128)
>>>>> imsave( "test.png", a, cmap=cm.summer,vmin=0,vmax=16383)
>>>>> b = Image.open("test.png" )
>>>>> ------------------------------------------
>>>>>
>>>>
>>>> The Image.fromarray function should do what you want. For example,
>>>>
>>>> import numpy as np # note: use of "from foo import *"
>>>> import Image # is discouraged where possible
>>>>
>>>> a = np.arange(128)[None,:] * np.ones(128)[:,None]
>>>>
>>>
>>> Sorry - I was playing around with a few iterations of this line, and
>>> didn't
>>> provide the most useful one. Your example:
>>>
>>> a = np.arange(128**2).reshape(128,128)
>>>
>>> should also work fine.
>>>
>>>
>>>> b = Image.fromarray(a)
>>>> c = np.asarray(b)
>>>> np.all(c == a)
>>>> -> True
>>>>
>>>> I hope that helps,
>>>>
>>>> Angus.
>>>>
>>>
>>> --
>>> AJC McMorland
>>> Post-doctoral research fellow
>>> Neurobiology, University of Pittsburgh
>>>
>>> ------------------------------------------------------------------------------
>>>
>>>
>>> _______________________________________________
>>> Matplotlib-users mailing list
>>> Mat...@li...
>>> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>>>
>>>
>>
>> Thank you Angus
>> but that's not exactly what i was looking for. The fromarray function is
>> very basic, so I would have to take care of all the RGBA of the array.
>> the
>> imshow and imsave functions take care of all that for example adding a
>> colormap. After choosing a reasonable colormap (vmin, vmax, ....) I would
>> like to convert this into a PIL image.
>>
>> Best Regard
>> Hans
>>
>> --
>> View this message in context:
>> http://old.nabble.com/imshow%2C-imsave-to-PIL-image-conversion-tp28736246p28739401.html
>> Sent from the matplotlib - users mailing list archive at Nabble.com.
>>
>>
>> ------------------------------------------------------------------------------
>>
>> _______________________________________________
>> Matplotlib-users mailing list
>> Mat...@li...
>> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>>
>
> ------------------------------------------------------------------------------
>
> _______________________________________________
> Matplotlib-users mailing list
> Mat...@li...
> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>
>
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> That's doing it, thought there might be an internal way within matplotlib, > but I could figure one. I think you can use the agg backend and the corresponding Canvas'es method canvas.tostring_rgb() . Then you can load this in PIL by Image.fromstring. Well, I simply send you my PIL backend. Tell me if it's still working ... Friedrich
On Tue, Jun 1, 2010 at 2:22 PM, rugspin <pie...@we...> wrote: > That's doing it, thought there might be an internal way within matplotlib, > but I could figure one. If you need more hard-core way of doing this, a = np.arange(16384).reshape(128, 128) from matplotlib.colors import Normalize import matplotlib.cm as cm norm = Normalize(vmin=0, vmax=16383) cmap = cm.summer A = (cmap(norm(a))*255).astype(np.uint8) import Image pilim = Image.fromarray(A, "RGBA")
Thanks Jae-Joon and Friedrich I will try out both solutions. Regards Hans Jae-Joon Lee wrote: > > On Tue, Jun 1, 2010 at 2:22 PM, rugspin <pie...@we...> wrote: >> That's doing it, thought there might be an internal way within >> matplotlib, >> but I could figure one. > > If you need more hard-core way of doing this, > > a = np.arange(16384).reshape(128, 128) > > from matplotlib.colors import Normalize > import matplotlib.cm as cm > norm = Normalize(vmin=0, vmax=16383) > cmap = cm.summer > > A = (cmap(norm(a))*255).astype(np.uint8) > > import Image > pilim = Image.fromarray(A, "RGBA") > > ------------------------------------------------------------------------------ > > _______________________________________________ > Matplotlib-users mailing list > Mat...@li... > https://lists.sourceforge.net/lists/listinfo/matplotlib-users > > -- View this message in context: http://old.nabble.com/imshow%2C-imsave-to-PIL-image-conversion-tp28736246p28753655.html Sent from the matplotlib - users mailing list archive at Nabble.com.