Cochran, Travis wrote:
> I'm trying to use the PIL to create a grayscale ramp, dark to light. I
> am able to generate an image but it is solid black. Am I using
> frombuffer wrong? Here is my code.
>
> from PIL import Image
>
> #Creates the list of codes from 0 to 255
> data = range(256)
> #Creates an image out of those codes
> im = Image.frombuffer("L", (256, 1), str(data), "raw", "L", 0, 1)
^^^^^^^^^
str(data) turns the list into a 1170 byte string representation of the
list, beginning "[0, 1, 2,". Translated back to byte values, this is
[91, 48, 44, 32, 49, 44, 32, 50, 44, 32], not [0, 1, 2]. Your "solid
black" is actually a dappled dark grey.
What you want is a 256 byte string of ascending values, which would
begin (in python's string notation) "\x00\x01\x02". One way to get this
would be:
# you can leave out the square brackets for python 2.4 +
data = ''.join([chr(x) for x in range(256)])
im = Image.frombuffer("L", (256, 1), data, "raw", "L", 0, 1)
Note, here:
> #Resizes the image to make it easy to view
> im = im.resize((256, 768)).show()
you are setting im to None, because that is what .show() returns. You
probably don't mean this, and would be better using two lines:
im = im.resize((256, 768))
im.show()
douglas
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