Python PIL Image.tostring()

python python-imaging-library pyopengl
ahoffer picture ahoffer · Jul 20, 2011 · Viewed 16.7k times · Source

I'm new to Python and PIL. I am trying to follow code samples on how to load an image into to Python through PIL and then draw its pixels using openGL. Here are some line of the code:

from Image import *
im = open("gloves200.bmp") 
pBits = im.convert('RGBA').tostring()

.....

glDrawPixels(200, 200, GL_RGBA, GL_UNSIGNED_BYTE, pBits)

This will draw a 200 x 200 patch of pixels on the canvas. However, it is not the intended image-- it looks like it is drawing pixels from random memory. The random memory hypothesis is supported by the fact that I get the same pattern even when I attempt to draw entirely different images.Can someone help me? I'm using Python 2.7 and the 2.7 version of pyopenGL and PIL on Windows XP.

screen shot

Answer

Eryk Sun picture Eryk Sun · Jul 20, 2011

I think you were close. Try:

pBits = im.convert("RGBA").tostring("raw", "RGBA")

The image first has to be converted to RGBA mode in order for the RGBA rawmode packer to be available (see Pack.c in libimaging). You can check that len(pBits) == im.size[0]*im.size[1]*4, which is 200x200x4 = 160,000 bytes for your gloves200 image.

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