CODEWITHSUNDEEP
pythonintegerpython-imaging-librarybitunsigned
Marmstrong
Marmstrong

Reputation: 1786

How to get a 16bit Unsigned integer in python

I currently read off pixels from an image using python PIL. These pixels are 16bit greyscale and are unsigned. However, whenever PIL reads them in it thinks they are signed and makes values that should be something like 45179 into -20357.

org_Image = Image.open(image)
org_Data = org_Image.load()
width, height = org_Image.size

    for y in range(0, height):
        temprow_data = []
        for x in range(0, width):
             temprow_data.append(org_Data[x, y])

How do I go about getting PIL to output unsigned instead of signed integers? Or is there a really easy way of taking the PIL input and converting it after?

Upvotes: 6

Views: 34244

Answers (2)

User
User

Reputation: 14863

Here is a solution with structs since I do not know how python represents negative numbers binarily.

import struct
struct.unpack('H', struct.pack('h', number))

It packs it as a short (2 bytes) and unpacks it as an unsigned short.

Upvotes: 8

Joran Beasley
Joran Beasley

Reputation: 113950

>>> import numpy as np
>>> np.array([-20357],dtype="uint16")
array([45179], dtype=uint16)

in your case when you are done looping over everything and you have it in a list

just call np.array(my_list,dtype="uint16")

Upvotes: 3

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