What kind of data is not expected to compress well with DEFLATE compression?

Question

What type of data is less efficiently compressed when using DEFLATE compression?

Answer

Files that have already been compressed (ZIP-compressed data such as Word documents (.docx)/Excel books (.xlsx), DEFLATE-compressed data, highly compressed image data such as GIF/JPEG/PNG, etc.) fall under data with poor compression efficiency.

Since compression processing is performed without distinction even on already compressed files, there is a possibility that the file size will increase due to recompression.

In addition, HULFT Square does not recommend compression for data with poor compression efficiency from the viewpoint of not wasting CPU resources.

Please note that even if DEFLATE compression is specified when transferring data for lower versions than HULFT8, the data will be transferred without compression.