Azure Functions，缩略图图像大小大于原始图像

Question

我已经使用这篇 Background image thumbnail processing with Azure Functions and NodeJS 文章创建了缩略图 image.An 图片已创建 successfully.But 图片大小已确定 increased.How 会发生这种情况吗？它一定很小，不是吗？我该如何解决这个奇怪的问题？

这是 Blob 存储上的原始图像

处理后（缩略图）

这是 Azure 函数（节点）：

var Jimp = require("jimp");

module.exports = (context, myBlob) => {

    // Read image with Jimp
    Jimp.read(myBlob).then((image) => {

        // Manipulate image
        image
            .resize(200, Jimp.AUTO) 
            .greyscale()
            .getBuffer(Jimp.MIME_JPEG, (error, stream) => {

                // Check for errors
                if (error) {
                    context.log(`There was an error processing the image.`);
                    context.done(error);
                }
                else {
                    context.log(`Successfully processed the image`);

                    // Bind the stream to the output binding to create a new blob
                    context.done(null, stream);

                }

            });

    });

};

Answer 1

我已经找到了解决方案。

The default quality for JPEGs is 100. You should set this to something lower to gain compression:

您可以在此处阅读更多相关信息：Image is resized down and gets bigger file size

我必须如图所示设置 .quality(50) below.This 问题仅在于 JPEGs。

var Jimp = require("jimp");

module.exports = (context, myBlob) => {

    // Read image with Jimp
    Jimp.read(myBlob).then((image) => {

        // Manipulate image
        image
            .resize(200, Jimp.AUTO)
            .greyscale()
            .quality(50) // set the quality for JPEGs
            .getBuffer(Jimp.MIME_JPEG, (error, stream) => {

                // Check for errors
                if (error) {
                    context.log(`There was an error processing the image.`);
                    context.done(error);
                }
                else {
                    context.log(`Successfully processed the image`);
                    // Bind the stream to the output binding to create a new blob
                    context.done(null, stream);

                }

            });

    });

};

Answer 2

我遇到了同样的问题，我使用了 sharp，它对我有用。如果您需要更多帮助，请告诉我，我会分享我完整的功能代码。

 const sharp = require('sharp');
 const thumbnailWidth = 250
 module.exports = async (context, myBlob) => {
    
      let thumbBuffer
      const image = await sharp(myBlob)
      image.resize({ width: thumbnailWidth })
      return thumbBuffer = await image.toBuffer()
 }

Azure Functions，缩略图图像大小大于原始图像

Azure Functions , Thumbnail image size is larger than original image

image

thumbnails

azure

node.js

azure-functions