Pandas - image to DataFrame

Question

I want to convert an RGB image into a DataFrame, so that I have the co-ordinates of each pixel and their RGB value.

         x   y   red  green  blue
0        0   0   154      0     0
1        1   0   149    111     0
2        2   0   153      0     5
3        0   1   154      0     9
4        1   1   154     10    10
5        2   1   154      0     0

I can extract the RGB into a DataFrame quite easily

colourImg = Image.open("test.png")
colourPixels = colourImg.convert("RGB")
colourArray = np.array(colourPixels.getdata())

df = pd.DataFrame(colourArray, columns=["red","green","blue"])

But I don't know how to get the X & Y coordinates in there. I could write a loop, but on a large image that takes a long time.

Answer 1

Try using np.indices unfortunately it ends up with a array where the coordinate is the first dimension, but you can do a bit of np.moveaxis to fix that.

colourImg = Image.open("test.png")
colourPixels = colourImg.convert("RGB")
colourArray = np.array(colourPixels.getdata()).reshape(colourImg.size + (3,))
indicesArray = np.moveaxis(np.indices(colourImg.size), 0, 2)
allArray = np.dstack((indicesArray, colourArray)).reshape((-1, 5))


df = pd.DataFrame(allArray, columns=["y", "x", "red","green","blue"])

It's not the pretiest, but it seems to work (edit: fixed x,y being the wrong way around).