Azure Computer Vision 之 Smart Crop 智能裁剪图片

前言

一个网站通常有许多地方会用到同一张图，但是比例又不一样.

一般的做法就是用 CSS 的 cover 和 contain 来处理.

由于 cover 只会保留中间信息, 所以很多时候需要人工裁剪.

于是就有了智能裁剪的需求了.

Azure Computer Vision

参考:

价格还可以

实现步骤

1. 到 Azure portal 创建 Computer Vision

没有什么特别的, 默认就可以了 (注: 一个 account 只能有一个 free 的 Computer Vision 哦)

2. 进入 Computer Vision Resource > Keys and Endpoint 把 key 和 endpoint 抄起来

3. 安装 SDK

dotnet add package Microsoft.Azure.CognitiveServices.Vision.ComputerVision

2 个核心功能, 第 1 个是获取全图焦点, 第 2 个是给定要求智能裁剪

[HttpPost("SmartCrop")]
public async Task<ActionResult> SmartCropAsync()
{
    var subscriptionKey = "key";
    var endpoint = "https://jbreviews-cv.cognitiveservices.azure.com/";
    var client = new ComputerVisionClient(new ApiKeyServiceClientCredentials(subscriptionKey))
    {
        Endpoint = endpoint
    };
    var imageFileFullPath = @"WebApi\Controller\Test\SmartCrop\10.png";
    using var imageStream = new FileStream(imageFileFullPath, FileMode.Open);
    // get area of interest
    var areaOfInterestResult = await client.GetAreaOfInterestInStreamAsync(imageStream); // 这里返回之后 imageStream 就自动被 close 了
    using var image = Image.Load(imageFileFullPath);
    var croppedImage = image.Clone(imageProcessing =>
    {
        imageProcessing.Crop(new Rectangle(
            x: areaOfInterestResult.AreaOfInterest.X,
            y: areaOfInterestResult.AreaOfInterest.Y,
            width: areaOfInterestResult.AreaOfInterest.W,
            height: areaOfInterestResult.AreaOfInterest.H)
        );
    });
    croppedImage.SaveAsJpeg(
        @"WebApi\Controller\Test\SmartCrop\11.png", new SixLabors.ImageSharp.Formats.Jpeg.JpegEncoder
        {
            Quality = 85
        }
    );
    
    // get smart crop image
    using var imageStream2 = new FileStream(imageFileFullPath, FileMode.Open);
    var croppedImageStream = await client.GenerateThumbnailInStreamAsync(300, 100, imageStream2, smartCropping: true);
    using var imageFileStream = System.IO.File.Create(@"WebApi\Controller\Test\SmartCrop\12.png");
    croppedImageStream.CopyTo(imageFileStream);
    return Ok();
}