I'm somewhat new to both libraries...is there any way to create a 2D array of pixel values from an image object from the Python Image Library? I'd like to do some arithmetic on the values.
Am Mittwoch, 30. August 2006 19:20 schrieb Ghalib Suleiman:
I'm somewhat new to both libraries...is there any way to create a 2D array of pixel values from an image object from the Python Image Library? I'd like to do some arithmetic on the values.
Yes. To transport the data:
import numpy image = <some PIL image> arr = numpy.fromstring(image.tostring(), dtype=numpy.uint8)
(alternately use dtype=numpy.uint32 if you want RGBA packed in one number). arr will be a 1d array with length (height * width * b(ytes)pp). Use reshape to get it into a reasonable form. HTH, Johannes
Johannes Loehnert wrote:
Am Mittwoch, 30. August 2006 19:20 schrieb Ghalib Suleiman:
I'm somewhat new to both libraries...is there any way to create a 2D array of pixel values from an image object from the Python Image Library? I'd like to do some arithmetic on the values.
Yes.
To transport the data:
import numpy image = <some PIL image> arr = numpy.fromstring(image.tostring(), dtype=numpy.uint8)
(alternately use dtype=numpy.uint32 if you want RGBA packed in one number).
arr will be a 1d array with length (height * width * b(ytes)pp). Use reshape to get it into a reasonable form.
On a related note, does anyone have a good recipe for converting a PIL image to a wxPython image? The last time I tried this, the best I could come up with was: stream = cStringIO.StringIO() img.save(stream, "png") # img is PIL Image stream.seek(0) image = wx.ImageFromStream(stream) # image is a wxPython Image -tim
Tim Hochberg wrote:
Johannes Loehnert wrote:
I'm somewhat new to both libraries...is there any way to create a 2D array of pixel values from an image object from the Python Image Library? I'd like to do some arithmetic on the values.
the latest version of PIL (maybe not released yet) supports the array interface, so you may be able to do something like: A = numpy.asarray(PIL_image) see the PIL page: http://effbot.org/zone/pil-changes-116.htm where it says: Changes from release 1.1.5 to 1.1.6 Added "fromarray" function, which takes an object implementing the NumPy array interface and creates a PIL Image from it. (from Travis Oliphant). Added NumPy array interface support (__array_interface__) to the Image class (based on code by Travis Oliphant). This allows you to easily convert between PIL image memories and NumPy arrays: import numpy, Image i = Image.open('lena.jpg') a = numpy.asarray(i) # a is readonly i = Image.fromarray(a)
On a related note, does anyone have a good recipe for converting a PIL image to a wxPython image?
Does a PIL image support the buffer protocol? There will be a: wx.ImageFromBuffer() soon, and there is now; wx.Image.SetDataBuffer() if not, I think this will work: I = wx.EmptyImage(width, height) DataString = PIL_image.tostring() I.SetDataBuffer(DataString) This will only work if the PIL image is an 24 bit RGB image, of course. Just make sure to keep DataString around, so that the data buffer doesn't get deleted. wx.ImageFromBuffer() will do that foryou, but it's not available until 2.7 comes out. Ideally, both PIL and wx will support the array interface, and we can just do: I = wx.ImageFromArray(PIL_Image) and not get any data copying as well. Also, Robin has just added some methods to directly manipulate wxBitmaps, so you can use a numpy array as the data buffer for a wx.Bitmap. This can help prevent a lot of data copies. see a test here: http://cvs.wxwidgets.org/viewcvs.cgi/wxWidgets/wxPython/demo/RawBitmapAccess.py?rev=1.3&content-type=text/vnd.viewcvs-markup -Chris -- Christopher Barker, Ph.D. Oceanographer NOAA/OR&R/HAZMAT (206) 526-6959 voice 7600 Sand Point Way NE (206) 526-6329 fax Seattle, WA 98115 (206) 526-6317 main reception Chris.Barker@noaa.gov
participants (4)
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Christopher Barker -
Ghalib Suleiman -
Johannes Loehnert -
Tim Hochberg