main.py

import cv2 as cv
import numpy as np

def nothing(x):
    pass

def resize(h, w, img):
    img_h = len(img)
    img_w = len(img[0])

    #print(img_h, img_w)
    
    e = energy(img)

    if h < img_h:
        e = np.transpose(e, (1, 0, 2))
        img = np.transpose(img, (1, 0, 2))
        trace = findMinPath(e)
        img = remove(trace, img)
        e = np.transpose(e, (1, 0, 2))
        img = np.transpose(img, (1, 0, 2))
    if h > img_h:
        pass #do after
    if w < img_w:
        trace = findMinPath(e)
        img = remove(trace, img)
    if w > img_w:
        pass #do after
    return img

def colorPath(trace, img, color = (0, 0, 255)):
    r, c, _ = img.shape
    for i in range(r):
        img[i][trace[i]] = color
    return img


def remove(trace, img):
    r, c, _ = img.shape
    newImg = np.zeros((r, c - 1, 3), dtype=np.uint8)

    for i in range(r):
        newImg[i] = np.delete(img[i], trace[i], axis = 0)

    return newImg

def energy(img):
    img = np.array(img, dtype=int)

    img1 = np.delete(img, 0, 0)
    img2 = np.delete(img, 0, 1)
    img1 = np.insert(img1, len(img1) - 1, [127, 127, 127], axis = 0)
    img2 = np.insert(img2, len(img2[0]) - 1, [127, 127, 127], axis = 1)

    return abs(img - img1) + abs(img - img2)

def findMinPath(e):
    r, c, _ = e.shape
    dp = np.zeros((r, c), dtype=int)

    dp[0] = np.sum(e[0], axis = 1)
    
    for i in range(1, r):
        dp[i][:-1] = np.minimum(dp[i - 1][:-1], dp[i - 1][1:])
        dp[i][-1] = dp[i - 1][-1]
        dp[i][1:] = np.minimum(dp[i][1:], dp[i - 1][:-1])
        dp[i] += np.sum(e[i], axis = 1)

    trace = np.zeros(r, dtype=int)
    last = 0

    for i in range(1, c):
        if dp[r - 1][i] < dp[r - 1][last]:
            last = i

    trace[r - 1] = last
    for i in range(r - 1, 0, -1):
        last = trace[i]
        minVal = dp[i - 1][last]
        trace[i - 1] = last
        if last > 0:
            minVal = min(minVal, dp[i - 1][last - 1])
            if minVal == dp[i - 1][last - 1]:
                trace[i - 1] = last - 1
        if last < c - 1:
            minVal = min(minVal, dp[i - 1][last + 1])
            if minVal == dp[i - 1][last + 1]:
                trace[i - 1] = last + 1
        #trace[i] = trace[i] + i * c

    return trace


def main():
    root = 'img/'

    imgPath = root + 'img1.png'
    #imgPath = root + 'img2.jpg'

    print(imgPath)

    img = cv.imread(imgPath)

    cv.namedWindow('image')
    cv.namedWindow('slider', cv.WINDOW_NORMAL)
    cv.resizeWindow('slider', 512, 64)
    cv.createTrackbar('Height', 'slider', len(img), 2 * len(img), nothing)
    cv.createTrackbar('Width', 'slider', len(img[0]), 2 * len(img[0]), nothing)

    cv.imshow('slider', np.full(1, 255, dtype=np.uint8))

    while (True):
        h = cv.getTrackbarPos('Height', 'slider')
        w = cv.getTrackbarPos('Width', 'slider')

        if h != len(img) or w != len(img[0]):
            img = resize(h, w, img)

        cv.imshow('image', img)

        pressKey = cv.waitKey(1) & 0xFF

        if pressKey == ord('q'):
            break

    cv.destroyAllWindows()

if __name__ == "__main__":
    main()