Scale an image by max_width and/or max_height using Wand

gistfile1.py

from wand.image import Image


def scale_image(filename, max_width=0, max_height=0, replace=False):
    """Resize an image by filename using wand (Imagemagick)
    Returns tuple of filename, width and height."""

    # Get filename and file format unsafely.
    fname, fmat = filename.split('.')
    # Create or use current filename
    new_filename = filename if replace else fname + '_resized.' + fmat

    with Image(filename=filename) as img:
        width, height = img.size

        # Skip Resize if not max_width or max_height.
        if not (max_width or max_height):
            return (filename, width, height)

        # Skip resize if size is under max dimensions
        if (width < max_width) and (height < max_height):
            return (filename, width, height)

        # Proceed with image resize
        with img.clone() as i:
            # Generate a list of scale to 1.0: 0.1, 0.2, 0.3...
            for d in reversed([float(j) / float(10) for j in range(1, 11)]):

                i.resize(int(i.width * d), int(i.height * d))

                if max_width and max_height:
                    if (i.width < max_width) and (i.height < max_height):
                        i.save(filename=new_filename)
                        return (filename, i.width, i.height)

                elif max_width:
                    if i.width < max_width:
                        i.save(filename=new_filename)
                        return (filename, i.width, i.height)

                elif max_height:
                    if i.height < max_height:
                        i.save(filename=new_filename)
                        return (filename, i.width, i.height)

                else:
                    i.save(filename=new_filename)
                    return (filename, i.width, i.height)


# Test call
print scale_image('ish.png', max_width=600, max_height=400)  # 1600 x 900 image
# Returns ('ish.png', 483L, 271L), writes the new image in disk.