Drop JPGs — or any pictures — and arrange them. Each becomes a page. JPEGs are placed in the PDF byte for byte, so nothing is re-compressed, and the page proves it with a checksum.
Byte for byte
A PDF can hold a JPEG exactly as it is, so that is what this page does: the bytes of your JPG become the picture on the page, unchanged. After the PDF is written, the SHA-256 of each embedded JPEG is compared with the file it came from, and the PDF is offered only when they match.
Phone photos often store a sideways picture with a note saying how to turn it. PDF viewers ignore that note, so this page turns the picture upright with the page's own drawing instructions — still without re-encoding it.
Other pictures, pages and privacy
PNG, WebP and other pictures are embedded losslessly, with transparency where they have it. “Smaller PDF” writes those as JPEG at matched quality instead; JPEGs are never touched.
Pages fit each picture by default, or use A4, Letter or Legal with a margin; orientation follows each picture or is fixed. The PDF carries no author, no file names and no dates — only a title if you type one. ID photos and scanned documents never leave this device.