Convert PIL Image to byte array?

Question

I have an image in PIL Image format. I need to convert it to byte array.

img = Image.open(fh, mode='r')  
roiImg = img.crop(box)

Now I need the roiImg as a byte array.

Please supply more detail. In what format is the byte array supposed to be? The raw pixels values are available via `Image.getdata()`, which returns the internal representation PIL uses for an image in a particular format on a particular platform. — dhke, Oct 13 '15 at 11:57
Not sure, but it sounds like you need to use the`Image`'s [`getdata()`](http://pillow.readthedocs.org/en/3.0.x/reference/Image.html#PIL.Image.Image.getdata) method. — martineau, Oct 13 '15 at 12:08
My objective is to save the image in mysql database as a BLOB type. — Evelyn Jeba, Oct 13 '15 at 12:30
`imgByteArr = open("foo.png" 'rb').read()` Need `roiImg` in the same format as `imgByteArr` — Evelyn Jeba, Oct 13 '15 at 12:56

score 284 · Accepted Answer · edited Apr 04 '23 at 18:42

284

Thanks everyone for your help.

Finally got it resolved!!

import io
from PIL import Image

img = Image.open(fh, mode='r')
roi_img = img.crop(box)

img_byte_arr = io.BytesIO()
roi_img.save(img_byte_arr, format='PNG')
img_byte_arr = img_byte_arr.getvalue()

With this i don't have to save the cropped image in my hard disc and I'm able to retrieve the byte array from a PIL cropped image.

edited Apr 04 '23 at 18:42

patelnisheet

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answered Oct 14 '15 at 05:43

Evelyn Jeba

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can you please add import io? – Ran Locar Feb 04 '17 at 11:13
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For `format="jpg"` saving to bytes does not work while `"jpeg"` works for both files and bytes and `"jpg"` works for files only. – Evgeny Nozdrev Jan 16 '20 at 14:18
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How do I do the reverse of this? Any ideas? – Mooncrater Oct 26 '20 at 08:15
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@Mooncrater I believe it's like this: `stream = io.BytesIO(img_byte_array)` and then `img = Image.open(stream)` – Sean McCarthy Apr 27 '22 at 02:53
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Why `roi_img.tobytes()` does not work? – Simone Feb 20 '23 at 13:58
@Simone: Because of the requirement missing from the question but mentioned in [a comment](https://stackoverflow.com/questions/33101935/convert-pil-image-to-byte-array#comment54021344_33101935), that the result should be PNG-compressed. – Ben Voigt May 03 '23 at 18:57

score 59 · Answer 2 · edited Jan 06 '23 at 08:54

59

This is my solution:

from PIL import Image
import io

def image_to_byte_array(image: Image) -> bytes:
  # BytesIO is a file-like buffer stored in memory
  imgByteArr = io.BytesIO()
  # image.save expects a file-like as a argument
  image.save(imgByteArr, format=image.format)
  # Turn the BytesIO object back into a bytes object
  imgByteArr = imgByteArr.getvalue()
  return imgByteArr

edited Jan 06 '23 at 08:54

bfontaine

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answered May 09 '19 at 08:42

Nori

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What is the UTF returned? – Blue Robin Apr 16 '23 at 23:40

score 7 · Answer 3 · answered Nov 20 '19 at 07:56

7

I think you can simply call the PIL image's .tobytes() method, and from there, to convert it to an array, use the bytes built-in.

#assuming image is a flattened, 3-channel numpy array of e.g. 600 x 600 pixels
bytesarray = bytes(Image.fromarray(array.reshape((600,600,3))).tobytes())

answered Nov 20 '19 at 07:56

Chris Ivan

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From documentation https://pillow.readthedocs.io/en/stable/reference/Image.html#PIL.Image.Image.tobytes it is not recomended, as it save raw image data for each pixel. If you use PNG, JPG, e.t.c. then need to use BytesIO() in Image.save() – XCanG Feb 22 '20 at 13:28
Ah, I see. For my purposes, I didn't need the bytes data, since I immediately do numerical processing on the RBG values. Also, the question doesn't mention anything about saving the images, only converting them. Consider removing your down vote for that reason. – Chris Ivan Jun 08 '20 at 02:08

score -4 · Answer 4 · edited Jan 17 '21 at 12:57

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Python file read and extract binary array

import base64
with open(img_file_name, "rb") as f:
    image_binary = f.read()
    base64_encode = base64.b64encode(image_binary)
    byte_decode = base64_encode.decode('utf8')

edited Jan 17 '21 at 12:57

DuDa

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answered Jan 17 '21 at 12:29

yelran2003

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Convert PIL Image to byte array?

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