Image Format Comparison: PNG vs JPG vs WEBP vs AVIF

Quick answer: Use JPG for photos, PNG for sharp graphics and transparency, WEBP for modern web performance, and AVIF when you want maximum compression and can accept varying support.

JPG (photos, smaller files)

• Best for real-world photos and gradients
• Lossy compression (some quality loss)
• Not great for text, logos, or sharp edges

PNG (sharp edges, transparency)

• Best for screenshots, UI, logos, icons
• Lossless (crisp text and lines)
• Can be large for photos

WEBP (modern web default)

• Often smaller than JPG/PNG at similar quality
• Supports transparency
• Great choice for websites when you control delivery

AVIF (maximum compression)

• Very efficient for photos and some graphics
• Can be slower to encode
• Support varies across environments

• Web photos: start around 80–90 quality for JPG/WEBP and adjust visually.
• UI screenshots: prefer PNG or lossless WEBP to keep text crisp.
• Avoid re-saving the same image repeatedly; keep a master.

Key takeaways

• Definition: Practical quality tips (fast defaults) explains what you are looking at and why it matters in practice.
• Context: this section helps you interpret inputs and outputs correctly, not just run a tool.
• Verification: confirm assumptions (format, encoding, units, or environment) before changing anything.
• Consistency: apply one approach end-to-end so results are repeatable and easy to debug.

Common pitfalls

• Mistake: skipping validation and trusting the first output you see from Practical quality tips (fast defaults).
• Mistake: mixing formats or layers (for example, decoding the wrong field or using the wrong unit).

Quick checklist

1. Identify the exact input format and whether it is nested or transformed multiple times.
2. Apply the minimal transformation needed to make it readable.
3. Validate the result (structure, encoding, and expected markers).
4. If the result still looks encoded, repeat step-by-step and stop as soon as it becomes clear.

1. Is it a photo? → JPG or WEBP (AVIF if supported and tested)
2. Is it a logo/screenshot/text? → PNG (or lossless WEBP if you know it works for your use case)
3. Do you need transparency? → PNG or WEBP
4. Do you need broad compatibility? → JPG/PNG

Key takeaways

• Definition: Decision guide (what to use) explains what you are looking at and why it matters in practice.
• Context: this section helps you interpret inputs and outputs correctly, not just run a tool.
• Verification: confirm assumptions (format, encoding, units, or environment) before changing anything.
• Consistency: apply one approach end-to-end so results are repeatable and easy to debug.

Common pitfalls

• Mistake: skipping validation and trusting the first output you see from Decision guide (what to use).
• Mistake: mixing formats or layers (for example, decoding the wrong field or using the wrong unit).

Quick checklist

1. Identify the exact input format and whether it is nested or transformed multiple times.
2. Apply the minimal transformation needed to make it readable.
3. Validate the result (structure, encoding, and expected markers).
4. If the result still looks encoded, repeat step-by-step and stop as soon as it becomes clear.

• Using PNG for all photos (huge pages, slow loads)
• Using JPG for logos/text (fuzzy edges)
• Ignoring mobile performance (file size matters)

Key takeaways

• Definition: Common mistakes explains what you are looking at and why it matters in practice.
• Context: this section helps you interpret inputs and outputs correctly, not just run a tool.
• Verification: confirm assumptions (format, encoding, units, or environment) before changing anything.
• Consistency: apply one approach end-to-end so results are repeatable and easy to debug.

Common pitfalls

• Mistake: skipping validation and trusting the first output you see from Common mistakes.
• Mistake: mixing formats or layers (for example, decoding the wrong field or using the wrong unit).

Quick checklist

1. Identify the exact input format and whether it is nested or transformed multiple times.
2. Apply the minimal transformation needed to make it readable.
3. Validate the result (structure, encoding, and expected markers).
4. If the result still looks encoded, repeat step-by-step and stop as soon as it becomes clear.

Should I use WEBP everywhere?

For many modern web use cases, yes, but keep fallback formats if your audience includes older systems.

Why does my PNG look huge?

PNG is lossless and stores sharp edges well. For photos, switch to JPG/WEBP or reduce dimensions.

What should I do if the output still looks encoded?

Decode step-by-step. If you still see obvious markers (percent codes, escape sequences, or Base64-like text), the data is likely nested.

What is the safest way to avoid bugs?

Keep the original input, change one thing at a time, and validate after each step so you know exactly what fixed the issue.

Should I use the decoded value in production requests?

Usually no. Decode for inspection and debugging, but send the original encoded form unless your protocol explicitly expects decoded text.

Why does it work in one environment but not another?

Different environments often have different settings (time zones, keys, encoders, or parsing rules). Compare a known-good sample side-by-side.

• PNG Specification - PNG format spec.
• JPEG Standard (ITU-T T.81) - JPEG spec.
• GIF Specification - GIF89a spec.
• WebP - WebP format.
• AVIF - AVIF spec.
• SVG 2 - Vector graphics.
• TIFF Specification - TIFF reference.
• MDN Image File Type and Format Guide - Format comparison.
• ISO 10918-1 (JPEG) - JPEG ISO standard.
• ISO/IEC 15948 (PNG) - PNG ISO standard.

Key takeaways

• Definition: References clarifies what the input represents and what the output should mean.
• Why it matters: correct interpretation prevents downstream bugs and incorrect conclusions.
• Validation: confirm assumptions before changing formats, units, or encodings.
• Repeatability: use the same steps each time so results are consistent across environments.

Common pitfalls

• Mistake: skipping validation and trusting the first output you see in References.
• Mistake: mixing formats or layers (for example, decoding the wrong field or using the wrong unit).
• Mistake: losing the original input, making it impossible to reproduce the issue.

Quick checklist

1. Identify the exact input format and whether it is nested or transformed multiple times.
2. Apply the minimal transformation needed to make it readable.
3. Validate the result (structure, encoding, expected markers) before acting on it.
4. Stop as soon as the result is clear; avoid over-decoding or over-normalizing.