JPEG vs PNG: Which Image Format Should You Use?
JPEG is usually efficient for photographs with acceptable loss; PNG preserves pixels losslessly and supports alpha transparency.
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Comparison at a glance
JPEG
PNG
Quick answer
Choose JPEG for photographs when a smaller file is worth some irreversible image loss. Choose PNG for lossless raster storage, sharp flat-color graphics, repeated editing without new compression loss, or alpha transparency. The content and workflow—not a universal quality ranking—decide.
| Criteria | JPEG | PNG |
|---|---|---|
| Common compression | Lossy DCT-based | Lossless |
| Photographs | Usually compact | Often much larger |
| Sharp edges and text | May show artifacts | Preserves exact decoded pixels |
| Alpha transparency | Not in common JPEG | Supported |
What “lossy” and “lossless” mean here
The familiar JPEG process discards some visual information to reduce size. At a sensible setting, the change can be hard to notice in a photograph; aggressive compression can create blockiness, ringing, and smeared detail. Saving an edited JPEG repeatedly can introduce additional loss.
PNG reconstructs the encoded pixel values without compression loss. That does not make every PNG small or every source image truthful. It means the encoding does not approximate those stored values. PNG also supports indexed color, grayscale, truecolor, and optional alpha information.
Match the format to the asset
| Asset | Usually start with | Why |
|---|---|---|
| Photograph for delivery | JPEG | Continuous-tone imagery usually compresses efficiently with acceptable loss |
| Screenshot with small text or interface lines | PNG | Lossless storage avoids JPEG ringing around hard edges |
| Raster logo or overlay needing transparency | PNG | PNG supports alpha transparency |
| Working master that will be edited repeatedly | Lossless master | Avoid accumulating new JPEG compression loss at every save |
Use JPEG for camera-like continuous-tone images delivered where file size matters. Keep a lossless master during editing. Use PNG for interface captures, diagrams, logos represented as raster pixels, and images that require smooth transparency. If a graphic can remain vector, a vector format may be a better question than either choice.
Renaming is not conversion
Changing .jpg to .png in a filename does not recover detail already lost
to JPEG compression. Re-encoding a JPEG as PNG preserves the JPEG's current
decoded pixels; it cannot reconstruct information that was discarded earlier.
Sources
- 1. JPEG 1 — JPEG Committee
- 2. Portable Network Graphics (PNG) Specification (Third Edition) — World Wide Web Consortium
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