In order to compress your photos as much as possible without any loss of photo quality, WinZip should be configured to create Zipx files (best method compression).
With WinZip, "Best method" compression examines each file and selects the compression option most likely to supply the best compression results. If you are adding JPEG/JPG images (photos) to a Zipx file, WinZip will use Jpeg compression. If you add other file types, WinZip will use different compression methods including XZ, LZMA, PPMd, MP3, WAVPACK and others.
When you use advanced compression methods, the result will be a .zipx file and, in most cases, your recipients will need WinZip in order to unzip the files from your .zipx file. As always, WinZip's .zipx enhancement to the Zip file format has been published. This provides details regarding the implementation of these new compression methods on our website. Some utilities have implemented these changes and we hope and expect that developers of other Zip file utilities will also include support for these formats in the future.
Feel free to encourage your recipients to download and install the latest version of WinZip. They will be able to use it at no charge during the evaluation period. This will allow them to open your Zip files compressed with "Best method" and take advantage of faster transmission time, faster download time, and more efficient use of disk space.
If you have any questions about this information please email Technical Support.
Default compression - What it is, how to change it
Additional Compression Methods Specification
What is the difference between "Legacy" and "Best method" compression?
What is a Zipx File?