JPG 格式每次保存都会压缩图像，而 PNG 格式则不会。如果您要编辑、裁剪或合成 JPG 图片，请先转换为 PNG 格式，以保留原始像素。
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 .jpg 或 .jpeg 文件拖放到窗口的任意位置。转换器支持 CMYK 和 RGB JPG 格式，以及逐行扫描 JPG 格式。
JPG 被解压缩为完整的 8 位 RGB 像素。这些像素随后被写入采用 DEFLATE 压缩的 PNG 文件——不会造成进一步的质量损失。
单个文件直接下载；多个文件打包成一个压缩文件。保留原始文件名，扩展名替换为 .png。
PNG provides lossless compression with transparency support
Perfect for graphics, logos, and images requiring transparency
Deflate compression algorithm with alpha channel support
perfect for graphics with transparency with advanced PNG encoding
Perfect for graphics, logos, screenshots, web design
Handles lossy compression, small file size, universal support from JPG files
有损感知压缩与无损算法压缩
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).
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).
对有损到无损转换的合理预期。
