ImageIO test

I've found some differences with the decoded RGB pixel values output from Java's ImageIO, when compared with Python and ImageMagick. This project is just a simple test case the proves the problem.

Dependencies

Uses the Python Imaging Library (PIL)

pip install Pillow

And also requires ImageMagick (specifically, the convert command)

Run it!

./gradlew test

Here's the output on OSX:

Tool        : [x, y] = [  r,   g,   b]

Image IO    : [0, 0] = [145, 146, 164]
Python      : [0, 0] = [145, 146, 164]
ImageMagick : [0, 0] = [145, 146, 164]

Image IO    : [1, 0] = [137, 138, 156] <--- different to python
Python      : [1, 0] = [137, 139, 154]
ImageMagick : [1, 0] = [137, 139, 154]

Image IO    : [2, 0] = [148, 147, 161]
Python      : [2, 0] = [148, 147, 161]
ImageMagick : [2, 0] = [148, 147, 161]

Image IO    : [0, 1] = [150, 153, 168]
Python      : [0, 1] = [150, 153, 168]
ImageMagick : [0, 1] = [150, 153, 168]

Image IO    : [1, 1] = [138, 141, 156] <--- different to python
Python      : [1, 1] = [138, 142, 154]
ImageMagick : [1, 1] = [138, 142, 154]

Image IO    : [2, 1] = [145, 147, 159]
Python      : [2, 1] = [145, 147, 159]
ImageMagick : [2, 1] = [145, 147, 159]

Image IO    : [0, 2] = [154, 160, 172]
Python      : [0, 2] = [154, 160, 172]
ImageMagick : [0, 2] = [154, 160, 172]

Image IO    : [1, 2] = [146, 152, 164] <--- different to python
Python      : [1, 2] = [146, 153, 163]
ImageMagick : [1, 2] = [146, 153, 163]

Image IO    : [2, 2] = [144, 148, 157] <--- different to python
Python      : [2, 2] = [144, 148, 159]
ImageMagick : [2, 2] = [144, 148, 159]

Here's the output on Ubuntu:

Tool        : [x, y] = [  r,   g,   b]

Image IO    : [0, 0] = [145, 146, 164] 
Python      : [0, 0] = [145, 146, 164]
ImageMagick : [0, 0] = [145, 146, 164]

Image IO    : [1, 0] = [137, 138, 156] 
Python      : [1, 0] = [137, 138, 156]
ImageMagick : [1, 0] = [137, 138, 156]

Image IO    : [2, 0] = [148, 147, 161] 
Python      : [2, 0] = [148, 147, 161]
ImageMagick : [2, 0] = [148, 147, 161]

Image IO    : [0, 1] = [150, 153, 168] 
Python      : [0, 1] = [150, 153, 168]
ImageMagick : [0, 1] = [150, 153, 168]

Image IO    : [1, 1] = [138, 141, 156] 
Python      : [1, 1] = [138, 141, 156]
ImageMagick : [1, 1] = [138, 141, 156]

Image IO    : [2, 1] = [145, 147, 159] 
Python      : [2, 1] = [145, 147, 159]
ImageMagick : [2, 1] = [145, 147, 159]

Image IO    : [0, 2] = [154, 160, 172] 
Python      : [0, 2] = [154, 160, 172]
ImageMagick : [0, 2] = [154, 160, 172]

Image IO    : [1, 2] = [146, 152, 164] 
Python      : [1, 2] = [146, 152, 164]
ImageMagick : [1, 2] = [146, 152, 164]

Image IO    : [2, 2] = [144, 148, 157] 
Python      : [2, 2] = [144, 148, 157]
ImageMagick : [2, 2] = [144, 148, 157]

Conclusion

Hmm, Python and ImageMagick appear to give different results depending on the operating system. Java is actually consistent across both...