PDF to JPG is a rendering operation
PDF text and vector shapes are drawing instructions rather than a fixed pixel grid. Conversion renders those instructions onto a canvas at a chosen scale, then encodes the pixels as JPEG. The JPG no longer contains selectable text, links, forms, or vector geometry.
Convert one page, selected pages, or the complete document
A single page is appropriate for a preview or thumbnail. Selected ranges reduce work when only a few pages matter. All-page conversion can create many images, so sequential rendering and cancellation help keep memory predictable.
Render scale controls dimensions and fine detail
A higher render scale creates more output pixels and can make small text clearer, but it increases encoding time, memory use, and file size. It cannot recover detail absent from a low-resolution scan embedded in the PDF.
JPEG quality and ZIP packaging solve different problems
JPEG quality changes compression artifacts and bytes after rendering; it does not change pixel dimensions. Multi-page exports are often packaged as a ZIP so filenames and order remain together. Verify the archive entry count and decode representative images before deleting the PDF source.