python给图片添加半透明背景文字

原图：

效果图：

from PIL import Image, ImageDraw, ImageFont'''pos x1,y1,x2,y2矩形坐标对角点'''def drawRect(img, pos, **kwargs):transp = Image.new('RGBA', img.size, (0,0,0,0))draw = ImageDraw.Draw(transp, "RGBA")draw.rectangle(pos, **kwargs)img.paste(Image.alpha_composite(img, transp))def watermark(img_path,word):# 打开图片img1 = Image.open(img_path)# 图片的颜色模式必须是RBGA，不然不能文字半透明img1 = img1.convert('RGBA')width,height = img1.size# 计算页面高度 灰条为高度的1/5 当然scale = height/2 - height/10drawRect(img1,(0,scale,width,scale+ height/5), fill=(0,0,0,150))draw = ImageDraw.Draw(img1)# 字体大小为灰色快的一半font_size = int(height/10)font = ImageFont.truetype(r'./font/SourceHanSansCN-Normal.otf', font_size) # 字体大小# 计算字体位置。应为len()/4中文/2f_w = width/2 - len(word)/2*font_sizef_h = scale + height/10 - font_size/2# 字体坐标font_coordinate = (int(f_w),int(f_h))draw.text(font_coordinate, word,font=font, fill=(255, 255, 255, 100))return img1if __name__ == "__main__":img = watermark('./img/3.jpg','面向百度')img.show()