JPG vs PNG: Which Image Format Should You Use?

JPG (JPEG) and PNG are the two most widely used image formats on the internet and in digital documents. Here's the key difference in one sentence:

JPG uses lossy compression (smaller files, slight quality loss) — PNG uses lossless compression (larger files, perfect quality with transparency support).

Both formats can be converted to PDF using AuraPDF for sharing and archiving.

JPEG (Joint Photographic Experts Group) is a lossy image compression standard created in 1992 by the JPEG committee (ISO/IEC 10918). The file extension is commonly `.jpg` or `.jpeg` — they are identical formats.

How JPEG compression works: JPEG divides an image into 8×8 pixel blocks and applies a Discrete Cosine Transform (DCT) to each block, converting spatial pixel data into frequency components. High-frequency detail (which humans perceive less) is discarded or approximated, reducing file size.

Key characteristics: • Lossy compression — Each save/edit cycle introduces additional quality loss • Adjustable quality — Save at 100% (near-lossless, larger) to 10% (heavy compression, smaller) • No transparency — JPEG doesn't support alpha channels; transparent areas become white • Excellent for photographs — The compression algorithm is specifically designed for continuous-tone images (photos, paintings, gradients)

When to use JPG: • Photographs and real-world images • Social media uploads (Instagram, Facebook optimize for JPEG) • Email attachments where file size matters • Website hero images and backgrounds • Any image where slight quality loss is acceptable for significantly smaller files

PNG (Portable Network Graphics) is a lossless image format created in 1996 as a patent-free replacement for GIF. It's standardized as ISO/IEC 15948:2004.

How PNG compression works: PNG uses the DEFLATE algorithm (the same used in ZIP files) which compresses data without discarding any information. Every pixel is preserved exactly — the decompressed image is bit-for-bit identical to the original.

Key characteristics: • Lossless compression — No quality degradation, no matter how many times you edit and save • Transparency support — Full alpha channel with 256 levels of transparency per pixel • Larger file sizes — Lossless compression produces files 5–10× larger than equivalent JPEGs • Excellent for graphics — Sharp edges, text, logos, and screenshots compress efficiently

When to use PNG: • Screenshots (text renders sharply with lossless compression) • Logos and brand graphics (especially those with transparency) • UI elements, icons, and illustrations • Images requiring transparency or semi-transparency • Diagrams, charts, and technical illustrations • Any image where pixel-perfect quality is essential

Both JPEG and PNG images can be converted to PDF using AuraPDF's JPG to PDF and PNG to PDF converters.

The file size difference between JPG and PNG is significant and directly impacts loading times, storage costs, and email deliverability:

Typical file sizes for a 1920×1080 photograph: • PNG: 5–8 MB • JPG at 95% quality: 800 KB – 1.5 MB • JPG at 80% quality: 300–600 KB • JPG at 60% quality: 150–300 KB

Typical file sizes for a 1920×1080 screenshot (text + UI): • PNG: 200–800 KB (compresses efficiently due to large uniform color areas) • JPG at 95%: 400 KB – 1 MB (text may show compression artifacts) • JPG at 80%: 200–400 KB (visible artifacts around text edges)

The takeaway: PNG is surprisingly efficient for images with large areas of uniform color (screenshots, diagrams), but dramatically larger for photographs. JPEG wins decisively for photographic content.

If your PDF documents contain many images and the file is too large, use AuraPDF's Compress PDF tool to reduce the file size while maintaining readability.

JPEG quality loss is cumulative. Every time you open, edit, and re-save a JPEG, additional quality is lost. This is called generation loss and it's the biggest practical drawback of JPEG.

Visible JPEG artifacts include: • Block artifacts — Visible 8×8 pixel grid patterns, especially in smooth gradients • Ringing/halo artifacts — Bright or dark halos around sharp edges (text, logos) • Color banding — Smooth gradients become stepped or banded • Mosquito noise — Scattered noise around high-contrast edges

These artifacts are most noticeable at low quality settings (below 70%) and around text/sharp edges. For photographs viewed at normal size, JPEG at 80%+ quality is virtually indistinguishable from the original to most viewers.

PNG has zero quality loss. The image is always pixel-perfect, no matter how many times it's saved. This makes PNG essential for images that will be edited multiple times (working files, templates) and images with text where sharpness matters.

Convert JPG to PNG when: • You need to add transparency to an image • You're creating a master file for ongoing edits (avoid generation loss) • The image contains text that needs to stay sharp through edits

Convert PNG to JPG when: • You need to reduce file size for email or web upload • The image is a photograph without transparency • You're uploading to platforms that prefer JPEG (most social media)

Convert either format to PDF when: • You need to share images as a formal document • You're compiling multiple images into one organized file • You need the images to be printable with predictable results • You want to archive images in a universally readable format

AuraPDF makes all of these conversions free: • JPG to PDF — Convert JPEG photos to PDF • PNG to PDF — Convert PNG screenshots and graphics to PDF • PDF to JPG — Extract images from PDF as JPEG • PDF to PNG — Extract images from PDF as lossless PNG