Spider file with last line black

[Marriaga]

What did you do?

I ran the code below and then open the image in Fiji (ImageJ)

What did you expect to happen?

Create an image with a gradient that goes from 0 to 1 diagonally

What actually happened?

Created the image correctly but the last row of pixels is 0 (black). I don't know if this is a problem of Pillow in saving to spi or of imagej in opening spi.

What versions of Pillow and Python are you using?

4.1.1

from __future__ import division
from PIL import Image
import numpy as np

def gradient(i,j,S):
    return 1/2*(i+j)/(S-1)

# Create Image
S=512
Mpix=np.fromfunction(gradient,(S,S),dtype=np.float32,S=S)
Img=Image.fromarray(Mpix,mode="F")

# Save Image
Img.save("TestPIL_32.spi","spider")

[wiredfool]

I've taken a look at this, and I can confirm that it does show up in the Fiji interface with a black line. It's part of the image data, since it also shows up in the histogram.

I've also looked at the spider image in a hexeditor, and it's not there. So either Fiji is wrong, or there's an off by one somewhere in the image size such that it's reading one beyond the end of the image and filling that with 0s instead of actual data.

[radarhere]

I've created PR #5956 to resolve this.