ImageMagick is a powerful command-line tool that can be used to optimize images without sacrificing quality. Here are some techniques you can employ using ImageMagick:

1. Resize Images: Use the `-resize` option to resize images to the desired dimensions. This reduces the file size by reducing the image’s dimensions while maintaining the aspect ratio. For example:

   convert input.jpg -resize 800x600 output.jpg

2. Compress Images: Apply image compression to reduce file size while maintaining reasonable image quality. The `-quality` option controls the compression level. Lower values result in higher compression but potentially reduced image quality. Experiment with different values to find the right balance. For example:

   convert input.jpg -quality 80% output.jpg

3. Convert to Optimized Formats: ImageMagick supports various image formats. Converting images to optimized formats can result in smaller file sizes. For example, converting a PNG image to JPEG format can significantly reduce file size:

   convert input.png output.jpg

4. Strip Metadata: Images often contain metadata such as EXIF data, which can contribute to larger file sizes. Use the `-strip` option to remove metadata from the image:

   convert input.jpg -strip output.jpg

5. Optimize GIF Images: Use the `-layers` option to optimize GIF images by removing unnecessary frames and reducing the number of colors. This can significantly reduce file size without noticeable quality loss:

   convert input.gif -layers Optimize output.gif

6. Progressive JPEG: Convert JPEG images to progressive format using the `-interlace` option. Progressive JPEGs load gradually, allowing users to see a low-resolution preview of the image while it loads. This improves user experience without sacrificing quality:

   convert input.jpg -interlace Plane output.jpg

7. Batch Processing: ImageMagick can process multiple images in batch mode using wildcard characters. For example, to resize and compress all JPEG images in a directory, you can use:

   mogrify -resize 800x600 -quality 80% *.jpg

Remember to test the output images to ensure they meet your quality standards. Adjust the settings according to your specific requirements and consider striking a balance between file size reduction and acceptable image quality.