python opencv resize image keep aspect ratio code example

Example 1: python resize image keep aspect ratio

def resize_with_pad(im, target_width, target_height):
    '''
    Resize PIL image keeping ratio and using white background.
    '''
    target_ratio = target_height / target_width
    im_ratio = im.height / im.width
    if target_ratio > im_ratio:
        # It must be fixed by width
        resize_width = target_width
        resize_height = round(resize_width * im_ratio)
    else:
        # Fixed by height
        resize_height = target_height
        resize_width = round(resize_height / im_ratio)

    image_resize = im.resize((resize_width, resize_height), Image.ANTIALIAS)
    background = Image.new('RGBA', (target_width, target_height), (255, 255, 255, 255))
    offset = (round((target_width - resize_width) / 2), round((target_height - resize_height) / 2))
    background.paste(image_resize, offset)
    return background.convert('RGB')

Example 2: python cv2 resize keep aspect ratio

def image_resize(image, width = None, height = None, inter = cv2.INTER_AREA):
    # initialize the dimensions of the image to be resized and
    # grab the image size
    dim = None
    (h, w) = image.shape[:2]

    # if both the width and height are None, then return the
    # original image
    if width is None and height is None:
        return image

    # check to see if the width is None
    if width is None:
        # calculate the ratio of the height and construct the
        # dimensions
        r = height / float(h)
        dim = (int(w * r), height)

    # otherwise, the height is None
    else:
        # calculate the ratio of the width and construct the
        # dimensions
        r = width / float(w)
        dim = (width, int(h * r))

    # resize the image
    resized = cv2.resize(image, dim, interpolation = inter)

    # return the resized image
    return resized