PNG 格式非常适合图形，但不适合照片——文件体积会急剧增大。将 PNG 照片转换为 JPG 格式，可以在文件大小减少 10% 的情况下，保持 95% 的视觉质量。
或者将图片拖放到这里。
支持JPG, JPEG, PNG, WEBP, SVG, GIF, HEIC, HEIF, BMP, TIFF, HDR, JP2, RAF, PSD, CR3, DNG, APNG, AVIF, AVI, ESP, EXR, J2C, J2K, JXL, PFM, PNM, PPM, PSB, SGI, MPEG, PDF
将 PNG 文件拖放到工具中——可以是单个文件，也可以是批量文件。默认情况下，透明 PNG 文件会被扁平化处理，背景为白色（可配置）。
解码后的像素以 90 的质量通过 JPEG 编码器进行编码。照片内容压缩 8-12 倍；纯色图形压缩效率较低。
输出文件保留源文件名，但添加 .jpg 扩展名。典型结果：一个 4 MB 的 PNG 文件会变成一个 400–600 KB 的 JPG 文件，外观上没有任何区别。
Convert PNG to JPG for better compatibility and optimization
Improved file compatibility and optimized performance
Professional-grade conversion with quality preservation
excellent for photos with advanced JPG encoding
Perfect for photography, web images, social media
Handles lossless compression, transparency support, crisp graphics from PNG files
平面图形请使用 PNG 格式。照片通常应使用 JPG 格式。
Portable Network Graphics
Requires libpng-1.0.11 or later, libpng-1.2.5 or later recommended. The PNG specification does not support pixels-per-inch units, only pixels-per-centimeter. To avoid reading a particular associated image profile, use -define profile:skip=name (e.g. profile:skip=ICC).
Joint Photographic Experts Group JFIF format
Note, JPG is a lossy compression. In addition, you cannot create black and white images with JPG nor can you save transparency. Requires jpegsrc.v8c.tar.gz. You can set quality scaling for luminance and chrominance separately (e.g. -quality 90,70). You can optionally define the DCT method, for example to specify the float method, use -define jpeg:dct-method=float. By default we compute optimal Huffman coding tables. Specify -define jpeg:optimize-coding=false to use the default Huffman tables. Two other options include -define jpeg:block-smoothing and -define jpeg:fancy-upsampling. Set the sampling factor with -define jpeg:sampling-factor. You can size the image with jpeg:size, for example -define jpeg:size=128x128. To restrict the maximum file size, use jpeg:extent, for example -define jpeg:extent=400KB. To define one or more custom quantization tables, use -define jpeg:q-table=filename. These values are multiplied by -quality argument divided by 100.0. To avoid reading a particular associated image profile, use -define profile:skip=name (e.g. profile:skip=ICC).
透明度处理、质量设置以及何时不进行转换。
