解释图像的字节数组

Question

What is stored in the byte array of an image? I was working on a project in which it was needed to interpret what is stored in the byte array of an image. How do we interpret the elements of the byte array?

Note: Following is the code in python to generate the byte array

from array import array
f = open("temp.jpg", "rb")
bytes = bytearray(f.read())

Answer 1

You've tagged this with python-imaging-library, but you don't mention it anywhere in your question, and you aren't using it.

I strongly suspect that you actually want to be using it. You're not interested in the array of bytes that make up the JFIF header, compressed image data, EXIF segment, etc.; you want an array of pixel values .

So, first you have to install the Python imaging library. The modern version is named Pillow , and the docs have completely installation instructions, but often it's just pip install pillow .

And now, you can use it in your script:

>>> from PIL import Image
>>> img = Image.open("temp.jpg")
>>> img.mode
'RGB'
>>> img.getpixel((0, 0))
(3, 148, 231)

An Image object is sort of array-like already. The mode lets me know that this is an 8-bit RGB image, so each pixel will have 3 values—red, green, and blue intensities from 0 to 255. And the getpixel((0, 0)) returns me the red, green, and blue values for the top-left pixel.

If you really want a flat array, you can go that too:

>>> img.getdata()[0]
(3, 148, 231)

Or, if you want a flat array of bytes (alternating red-blue-green-red-blue-green) instead of tuples:

>>> img.getbytes()[0]
3