写在前面：本博客仅作记录学习之用，部分图片来自网络，如需使用请注明出处，同时如有侵犯您的权益，请联系删除！

文章目录

前言
局部放大
函数实现
- 单一局部放大置于图像内部
- 多局部放大拼接于图形侧面
- 主函数
效果
目标区域选取的方法
目标区域选取程序
目标区域选取效果
使用说明
总结
修改记录
致谢

前言

本博客仅为学习记录之用，目的在于后续若需要相关的有资可查。在言语上恐有诸多纰漏，如有错误，欢迎指出交流学习！
本博客所包含的大致内容: 图片某一局部放大并置于图形内部；图片多个局部放大并拼接在原图侧面。

局部放大

为什么要局部放大？无论的图像生成、修复、去污等等，如生成对抗方法；亦或是图像分割，如unet。对于方法的结果都需要进行有效的展示，凸显方法的优越性能，往往细节的部分才是我们所更加关注的。但往往在图像本身很难观察到这些细节，因此有意识的将需要的局部放大是展示效果的有效方法。

函数实现

单一局部放大置于图像内部

思路也简单，首先获取到需要关注的部分，然后在将其进行插值放大，最后放在原图的某一位置即可。

本函数参数传入图像，需要目标区域的指标，其次放在的位置，支持四个角以及中心，以及放大的倍数。
目标区域为矩形，长宽比任意。

def Partial_magnification(pic, target, location='lower_right', ratio=1):''':param pic: input pic:param target: Intercept area, for example [target_x, target_y, target_w, target_h]:param location: lower_right,lower_left,top_right,top_left,center:param ratio: gain:return: oringal pic, pic'''img = copy.copy(pic)w, h = pic.shape[1], pic.shape[0],target_x, target_y = target[0], target[1]target_w, target_h = target[2], target[3]cv2.rectangle(pic, (target_x, target_y), (target_x + target_w, target_y + target_h), (255, 255, 0), 2)new_pic = pic[target_y:target_y + target_h, target_x:target_x + target_w]new_pic = cv2.resize(new_pic, (target_w*ratio, target_h*ratio), interpolation=cv2.INTER_CUBIC)if location == 'lower_right':pic[h-1-target_h*ratio:h-1, w-1-target_w*ratio:w-1] = new_piccv2.line(pic, (target_x + target_w, target_y + target_h), (w-1-target_w*ratio, h-1-target_h*ratio), (255, 0, 0),2)elif location == 'lower_left':pic[h-1-target_h*ratio:h-1, 0:target_w*ratio] = new_picelif location == 'top_right':pic[0:target_h*ratio, w-1-target_w*ratio:w-1] = new_picelif location == 'top_left':pic[0:target_h*ratio, 0:target_w*ratio] = new_picelif location == 'center':pic[int(h/2-target_h*ratio/2):int(h/2+target_h*ratio/2),int(w/2-target_w*ratio/2):int(w/2+target_w*ratio/2)] = new_picreturn img, pic

多局部放大拼接于图形侧面

当存在多个局部需要放大时，若都置于原图内部，遮挡图片内容的可能性较大，因此将其置于图像侧面。

本函数仅支持两个局部区域放大。和第一个函数不同的是两个局部放大的区域长宽比需要一致，为了方便拼接。没有设置放大倍数，默认局部放大后拼接图片与原图等高。

def Partial_magnification_2(pic, target1, target2, *args):''':param pic: input pic:param target: Intercept area, for example [target_x, target_y, target_w, target_w]:param location: lower_right,lower_left,top_right,top_left,center:param ratio: gain:return: oringal pic, pic'''# imgg = copy.copy(pic)w, h = pic.shape[1], pic.shape[0],assert target1[0]+target1[2] < w and target1[1]+target1[3] < h,\'The target1 area is too large and exceeds the image size'assert target2[0]+target2[2] < w and target2[1]+target2[3] < h,\'The target2 area is too large and exceeds the image size'assert target1[2] > 10 or target1[3] > 10, \'The target1 area is too small, not recommended'assert target2[2] > 10 or target2[3] > 10, \'The target2 area is too small, not recommended'assert target1[0] > 0 and target1[0] < w, \'The starting point of the target1 area is beyond the scope of the image'assert target2[0] > 0 and target2[0] < w, \'The starting point of the target2 area is beyond the scope of the image'if target2[2] / target2[3] == target1[2] / target1[3]:  #R = target2[2]/target2[3]if target1[1] > target2[1]:target1_x, target1_y = target2[0], target2[1]target1_w, target1_h = target2[2], target2[3]target2_x, target2_y = target1[0], target1[1]target2_w, target2_h = target1[2], target1[3]else:target1_x, target1_y = target1[0], target1[1]target1_w, target1_h = target1[2], target1[3]target2_x, target2_y = target2[0], target2[1]target2_w, target2_h = target2[2], target2[3]cv2.rectangle(pic, (target1_x, target1_y), (target1_x + target1_w, target1_y + target1_h), (255, 250, 255), 2)cv2.rectangle(pic, (target2_x, target2_y), (target2_x + target2_w, target2_y + target2_h), (255, 252, 255), 2)new_pic1 = pic[target1_y:target1_y + target1_h, target1_x:target1_x + target1_w]new_pic1 = cv2.resize(new_pic1, (int(h//2 * R), h//2), cv2.INTER_CUBIC)new_pic2 = pic[target2_y:target2_y + target2_h, target2_x:target2_x + target2_w]new_pic2 = cv2.resize(new_pic2, (int(h//2 * R), h//2))img = np.zeros((h, int(h//2 * R), 3), np.uint8)img[0:h//2, 0:int(h//2 * R)] = new_pic1img[h//2:h, 0:int(h//2 * R)] = new_pic2hmerge = np.hstack((pic, img))cv2.line(hmerge, (target1_x + target1_w, target1_y), (w, 0), (255, 255, 255), 2)cv2.line(hmerge, (target2_x + target2_w, target2_y + target2_h), (w, h), (255, 255, 255), 2)return  hmergeelse:raise ValueError('Make sure the aspect ratio of target is consistent !')

主函数

为方便复现提供了参考的主程序，如果需要批量放大，添加循环即可。

if __name__ == '__main__':img = cv2.imread(r'./test/Image_11L.jpg')  target1 = [250, 250, 100, 100]pic, pic1 = Partial_magnification(img, target1, location='lower_right', ratio=4)target2 = [180, 400, 100, 50]pic, pic2 = Partial_magnification(pic, target2, location='lower_left', ratio=2)hmerge = np.hstack((pic1, pic2))if max(hmerge.shape[0], hmerge.shape[1]) > 1000:# cv2.namedWindow('merge', 0)# cv2.resizeWindow('merge', 1000, int(1000*hmerge.shape[0]/hmerge.shape[1]))# cv2.imshow('merge', hmerge)# cv2.waitKey(0)# cv2.destroyAllWindows()hmerge = cv2.cvtColor(hmerge, cv2.COLOR_BGR2RGB)fig = plt.figure(figsize=(40, 20))  # figsize 尺寸plt.imshow(hmerge)plt.savefig('aaa_bbb.png', dpi=200)  # dpi分辨率plt.show()else:plt.imshow(hmerge)plt.show()

if __name__ == '__main__':img = cv2.imread(r'./test/Image_11L.jpg')  target1 = [250, 650, 100, 100]target2 = [450, 400, 100, 100]pic1 = Partial_magnification_2(img, target1, target2)hmerge = cv2.cvtColor(pic1, cv2.COLOR_BGR2RGB)fig = plt.figure(figsize=(30, 20))fig.patch.set_facecolor('gray')plt.imshow(hmerge)plt.savefig('aaa_bbb.png', dpi=300, bbox_inches='tight')plt.show()

效果

以下是两个函数的测试结果，主程序如上。

目标区域选取的方法

上述的目标的指定放大的区域全靠大致位置加不断调整，使得绘图不够直观的准确，今添加选取指定区域的方法，利用opencv 直接直观的选取指定区域。

目标区域选取程序

def on_EVENT_change(event, x, y, flags, param):if event == cv2.EVENT_LBUTTONDOWN:point.append((x, y))target.append((x, y))xy = "%d,%d" % (x, y)cv2.circle(copyImg, (x, y), 1, (255, 0, 0), thickness=-1)cv2.putText(copyImg, xy, (x, y), cv2.FONT_HERSHEY_COMPLEX_SMALL, 1.0, (0, 0, 0), thickness=1)cv2.imshow("image", copyImg)elif event == cv2.EVENT_LBUTTONUP:point.append((x, y))target.append((x, y))xy = "%d,%d" % (x, y)cv2.rectangle(copyImg, point[0], point[1], (0, 255, 0), thickness=1, lineType=8, shift=0)cv2.circle(copyImg, (x, y), 1, (255, 0, 0), thickness=-1)cv2.putText(copyImg, xy, (x, y), cv2.FONT_HERSHEY_COMPLEX_SMALL, 1.0, (255, 0, 0), thickness=1)cv2.imshow("image", copyImg)point.clear()elif event == cv2.EVENT_RBUTTONDOWN:cv2.imshow("image", img)cv2.setMouseCallback("image", on_EVENT_LBUTTONDOWN)def on_EVENT_LBUTTONDOWN(event, x, y, flags, param):if event == cv2.EVENT_LBUTTONDOWN:point.append((x, y))target.append((x, y))xy = "%d,%d" % (x, y)cv2.circle(img, (x, y), 1, (255, 0, 0), thickness=-1)cv2.putText(img, xy, (x, y), cv2.FONT_HERSHEY_COMPLEX_SMALL, 1.0, (0, 0, 0), thickness=1)cv2.imshow("image", img)elif event == cv2.EVENT_LBUTTONUP:point.append((x, y))target.append((x, y))xy = "%d,%d" % (x, y)cv2.rectangle(img, point[0], point[1], (0, 255, 0), thickness=1, lineType=8, shift=0)cv2.circle(img, (x, y), 1, (255, 0, 0), thickness=-1)cv2.putText(img, xy, (x, y), cv2.FONT_HERSHEY_COMPLEX_SMALL, 1.0, (255, 0, 0), thickness=1)cv2.imshow("image", img)point.clear()elif event == cv2.EVENT_RBUTTONDOWN:cv2.imshow("image", copyImg)cv2.setMouseCallback("image", on_EVENT_change)if __name__ == '__main__':  #Partial_magnification
# point、target、img、"image"不能修改，和前文定义函数绑定point = []target = []path = "xxx.jpg"img = cv2.imread(path)copyImg = copy.deepcopy(img)cv2.namedWindow("image")cv2.setMouseCallback("image", on_EVENT_LBUTTONDOWN)cv2.imshow("image", img)cv2.waitKey(0)cv2.destroyAllWindows()location = ['top_left', 'top_right', 'lower_right', 'lower_left', 'center']img = cv2.imread(path)  # C:\Users\Administrator\Desktop\dd.jpgfor i in range(len(target)//2):if target[2*i+1][0]-target[2*i][0]>0:target1 = [target[2*i][0], target[2*i][1], target[2*i+1][0]-target[2*i][0], target[2*i+1][1]-target[2*i][1]]else:raise ValueError('请从左往右，从下往上 框取区域')if i == 0:pic, pic1 = Partial_magnification(img, target1, location=location[i], ratio=2)else:pic, pic1 = Partial_magnification(pic, target1, location=location[i], ratio=2)fig = plt.figure(figsize=(20, 20))  # figsize 尺寸plt.imshow(cv2.cvtColor(pic, cv2.COLOR_BGR2RGB))plt.savefig('xxx.png', dpi=300, bbox_inches='tight')  # dpi 分辨率plt.show()

目标区域选取效果

使用说明

cv2上选取区域需要从左往右，从下往上框取区域（局部放大函数的限制），最多五个区域（放大后的区域选项决定。如果选取区域在一个图相交，影响选取时右键使用备份绘制。

总结

以上就是本文的主要内容，都是OpenCV和plt的基本使用上实现图像的局部放大。

修改记录

2022.10.17 ：添加目标区域选取的方法

致谢

欲尽善本文，因所视短浅，怎奈所书皆是瞽言蒭议。行文至此，诚向予助与余者致以谢意。

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