How to optimize image format and size to balance quality and loading performance?

When both image quality and loading performance need to be considered, optimization should be carried out collaboratively from three aspects: format selection, compression processing, and size adjustment. Generally, reasonable format selection is the foundation, targeted compression is the key, and matching display size is the guarantee. Format selection: Different scenarios are suitable for different formats. JPEG is suitable for photo images, balancing quality and size by adjusting the compression ratio; PNG-8 is preferred for images with transparent backgrounds or simple graphics, and WebP can be selected for complex transparent images; when quality, transparency, and compression rate need to be considered simultaneously, WebP or AVIF are better solutions, which can reduce the volume by more than 30% compared with traditional formats. Compression processing: Lossless compression is suitable for scenarios where details need to be retained, such as using TinyPNG and ImageOptim to remove redundant data; lossy compression is suitable for scenarios with low image quality requirements, adjusting parameters through tools such as Squoosh and ShortPixel to reduce the volume within an acceptable range of image quality loss. Size adjustment: Set the resolution according to the actual display size to avoid "using a large image for a small purpose". For example, web cover images usually do not need to exceed 2000 pixels in width, and mobile images can be controlled within 1080 pixels to reduce unnecessary loading burden. It is recommended to prioritize the WebP format, use automated compression tools for batch processing, and test loading performance through PageSpeed Insights to gradually optimize to a balanced state.