Open your favorite Terminal and run this command :

python convert2pdf.py

The application opens and looks like this :

Then, let's imagine that you want to merge these images, corresponding to the pages of a digital book, which are located in this :

In the application, you choose the path of the folder and the name of the pdf file that will contain the images mentioned above :

Et voilà ! The PDF File is generated ! You can find the pdf !