How to get each pixel value from a picture file!

[Steve Holden]

Lucas wrote:
> I want to change some pixel value in the picture file. how to do it?
> 
The most popular way is probably the Python Image Library, known to its 
friends as PIL:

   http://www.pythonware.com/products/pil/

You will see from

   http://www.pythonware.com/library/pil/handbook/image.htm

that images have .getpixel() and .putpixel() methods that will allow you 
to read and set individual pixels if you want. Be aware that the 
forthcoming release will give faster access using something called 
"pixel access objects", about which I know nothing.

> If I read the file in binary mode, a bit == a pixel ?
> 
Only for monochrome images, of course. Greyscale and color images have 
more bits per pixel, and some formats use a palette mapping to allow 
high color-fidelity with fewer bits per pixel (GIF is one such format).

Download PIL and play with it. I'm sure you'll have a lot of fun, and 
you can do a surprising amount of processing just noodling around in an 
interactive interpreter session.

regards
  Steve
-- 
Steve Holden       +44 150 684 7255  +1 800 494 3119
Holden Web LLC/Ltd          http://www.holdenweb.com
Skype: holdenweb       http://holdenweb.blogspot.com
Recent Ramblings     http://del.icio.us/steve.holden