image to pdf, output file too large in desktop version

image to pdf.

It seems that the desktop version program does not simply merge images to a pdf file, but convert the image to jpg (or some other format) first.

For example, when I convert a 102KB tiff file (5036*7068 pixels) to pdf, the desktop version output a 5.21MB pdf file, while the online version output a 103KB pdf file.

How should I config the desktop version to get the same file size using online version?

Thanks!