Which of the following is the most accurate reason?

Question

A student uploads a PDF file to an online PDF-to-JPG converter website. After conversion, he downloads the JPG files but later notices:

The images are blurred

File size is much larger than expected

Text cannot be copied anymore

Which of the following is the most accurate reason?

1. A. The PDF was converted into raster images. (Correct answer)
2. B. The website reduced internet speed.
3. C. The browser changed the file extension.
4. D. The file was uncompressed using ZIP format

Correct Answer

Option A — The PDF was converted into raster images.

Detailed Solution & Explanation

The correct answer is The PDF was converted into raster images.

Key Points

• All three symptoms follow directly from converting vector content into raster form:
  • Blurred images — text in a PDF is normally stored as vector outlines that scale to any size without loss. Once rendered to JPG it becomes a fixed grid of pixels, so any enlargement produces visible softness and the chosen resolution caps the quality permanently.
  • Larger file size — a page of vector text is described compactly by curves and font references, whereas the same page as a raster image must store a colour value for every pixel. JPG's lossy compression cannot make up the difference, especially on text-heavy pages with sharp edges.
  • Text cannot be copied — a raster image contains no text layer at all, only pixels. There are no character codes left to select or search.

Additional Information

• Vector versus raster:

• Why the other options are wrong: internet speed affects transfer time, not image quality; a browser does not alter file contents when changing an extension; and ZIP is a lossless archive format that neither blurs images nor removes text.
• Recovering text from a raster image requires OCR (Optical Character Recognition), which analyses pixel patterns and reconstructs character codes. This is exactly why a scanned PDF is not searchable until OCR has been applied, whereas a digitally created PDF is searchable from the outset.
• JPG versus PNG: JPG uses lossy compression, suits photographs, and does not support transparency; PNG is lossless, handles sharp edges and text far better, and supports transparency — which makes PNG the better choice when converting document pages to images.