Written file is many times larger than the original?

[manuelpoelzl]

Hi, I have a problem, namely that the image written by Jimp-compact is many times larger than the original.
Here is my original file, which is slightly larger than 1MB.

The buffer length is also OK so far:

Now, however, as soon as I read in the file using Jimp, very questionable buffer sizes are coming up:

Thus, the written file then has a size of over 7MB, which is pretty much 7x the size of the original:

I am now wondering how this can be, unfortunately the documentation of jimp is not really informative in terms of options and customization of processes, so I hope someone here can help me.

Thanks in advance!