Get color palette of image on the clipboard

clipboardcolors.py

# requires
# numpy, PIL (and IPython, if you keep in the HTML repr stuff)

import itertools
import numpy as np

def _image_from_clipboard(algo="png"):
    if algo == "jpeg":
        from PIL import ImageGrab
        im = ImageGrab.grabclipboard().convert("RGB")
    elif algo == "png":
        # adapted from https://pillow.readthedocs.io/en/stable/_modules/PIL/ImageGrab.html#grabclipboard
        import sys
        import os
        import tempfile
        import subprocess
        from PIL import Image

        fh, filepath = tempfile.mkstemp(".png")
        os.close(fh)
        commands = [
            'try',
            f'    write (the clipboard as «class PNGf») to (open for access "{filepath}" with write permission)',
            'end try',
        ]
        script = ["osascript"]
        for command in commands:
            script += ["-e", command]
        subprocess.call(script)

        im = None
        if os.stat(filepath).st_size != 0:
            im = Image.open(filepath)
            im.load()
        os.unlink(filepath)
    return im

def colors_from_clipboard(algo="png"):
    """
    This returns a nice HTML repr of the common colors and their hexadecimal
    representation from the picture in the system clipboard.  Useful for
    getting a hexadecimal color palette given a plot.
    """

    from PIL import ImageGrab
    from IPython.display import HTML

    img = _image_from_clipboard(algo=algo)

    arr = np.array(img)
    arr = np.array(img)[:,:,(0,1,2)]

    r = arr[:,:,0].flatten().astype(np.uint32)
    g = arr[:,:,1].flatten().astype(np.uint32)
    b = arr[:,:,2].flatten().astype(np.uint32)

    sel = ((r > 230) & (g > 230) & (b > 230)) | ((r < 20) & (g < 20) & (b < 20))
    r = r[~sel]
    g = g[~sel]
    b = b[~sel]

    all_rgb = (r << 16) | (g << 8) | b
    unique_rgb, counts = np.unique(all_rgb, return_counts=True)
    top_rgb = unique_rgb[np.argsort(counts)[-12:]][::-1] # most to least common

    def dist_rgb(rgb1, rgb2):
        r1 = (rgb1 >> 16) & 0xff
        g1 = (rgb1 >> 8) & 0xff
        b1 = (rgb1 >> 0) & 0xff
        r2 = (rgb2 >> 16) & 0xff
        g2 = (rgb2 >> 8) & 0xff
        b2 = (rgb2 >> 0) & 0xff
        return ((r1-r2)**2 + (b1-b2)**2 + (g1-g2)**2)**0.5

    if len(top_rgb) > 1:
        deduped_rgb = [top_rgb[0]]
        for i,rgb in enumerate(top_rgb[1:],1):
            closest = min([dist_rgb(rgb,v) for v in top_rgb[:i]])
            if closest > 6:
                deduped_rgb.append(rgb)
        top_rgb = deduped_rgb

    def rgb_to_hex(v):
        r = (v >> 16) & 0xff
        g = (v >> 8) & 0xff
        b = (v >> 0) & 0xff
        return f"{r:02x}{g:02x}{b:02x}".upper()

    from IPython.display import HTML
    hex_values = list(map(rgb_to_hex,top_rgb))
    body = "<table>"
    for hv in hex_values:
        body += f'<tr style="background:white;"><td><svg width="40" height="10"><rect width="40" height="10" style="fill:#{hv};stroke-width:0;"/></svg></td><td><pre>#{hv}</pre></td></tr>\n'
    body += "</table>"
    return HTML(body)