이미지에서 A4 인쇄를 잘라냅니다.

코드에 대한 주의

코드

#カラー画像を受け取って紙を切り取って返す
def cutting_paper(img):
    x = 2000 #切り取り後のx座標
    y = int(x*1.415)
    img_gray = gray(img)
    #２値化
    ret,img_th1  = cv2.threshold(img_gray,220,255,cv2.THRESH_TOZERO_INV)
    img_not = cv2.bitwise_not(img_th1)
    ret,img_th2  = cv2.threshold(img_not,0,255, cv2.THRESH_BINARY | cv2.THRESH_OTSU )
    #輪郭抽出
    contours, hierarchy = cv2.findContours(img_th2, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)

    #２番目にでかい四角が紙の輪郭なのでpaper_tapを取り出す
    pic_tap = None #画像の輪郭
    paper_tap = None #紙の輪郭
    for i, con in enumerate(contours):
        size = cv2.contourArea(con)
        if pic_tap is None:
            pic_tap = (con,size)
            continue
        if pic_tap[1] <= size:
            pic_tap = (con,size)
            continue
        elif paper_tap is None:
            paper_tap = (con,size)
        elif paper_tap[1] <= size:
            paper_tap = (con,size)

    #直線近似して描画
    epsilon = 0.1*cv2.arcLength(paper_tap[0],True)
    paper_corners= cv2.approxPolyDP(paper_tap[0],epsilon,True)#紙の頂点座標
    fix_con = np.array([[[0,0]],[[x,0]],[[x,y]],[[0,y]]], dtype="int32")#整形後のサイズ

    M = cv2.getPerspectiveTransform(np.float32(paper_corners),np.float32(fix_con))#変換行列の生成
    img_trans = cv2.warpPerspective(img,M,(x,y))#変換
    return img_trans

img = cv2.imread('input.png',-1)
cv2.imwrite("output.png", img)
plt.imshow(plt.imread("output.png"))