I see pdftk get first in list as most recommended way when searching for editing PDF metadata in Ubuntu. But pdftk is no longer present in Ubuntu 18.04 repositories. Found a different tool named PDFMtEd, which is actually a GUI front-end for ExifTool.
First convert image files to PDF with command: Then resize PDF to standard size with command: Read more about pdfjam at here.
Attached document demonstrates calculations involved for a SEPIC converter. Calculations are based on “AN-1484 Designing A SEPIC Converter” by Dongbing Zhang from Texas Instruments.