Image Format Selection Guide - JPG vs PNG vs WebP | Omibox

When building a website, a designer once gave me a pile of PNG images, each several MBs in size. After uploading them, the website loaded terribly slow, and my boss thought it was a server issue. I later researched image formats and discovered there's actually a lot to know.

Common Format Comparison

Let's talk about the formats I use most effectively, each with its own use case:

JPG - The Veteran

Pros: Small file size, high compatibility, supported by all devices.

Cons: Lossy compression, does not support transparent backgrounds.

Best for: Photographs, complex images, social media sharing.

PNG - The Designer's Favorite

Pros: Lossless compression, supports transparent backgrounds, high quality.

Cons: Large file size, not suitable for photographs.

Best for: Logos, icons, images requiring transparency.

WebP - The Rising Star

Pros: 30% smaller than JPG, supports transparency, decent quality.

Cons: Older browsers don't support it (forget about IE).

Best for: Modern websites, mobile applications.

My Selection Strategy

Website Images

I now use WebP for all my website images, with JPG as a fallback:

This way, new browsers use WebP (faster), and older ones automatically degrade to JPG.

Social Media

For posting on social media like Twitter or Facebook, use JPG directly. Although WebP is smaller, many platforms will convert it to JPG anyway—it keeps things faster if you convert it beforehand.

Design Drafts

Use PNG when sending design drafts to clients to ensure quality. But remember to compress specific files, otherwise, you might fail to send them via email.

Conversion Tips

Format conversion is simple, but there are a few pitfalls to watch out for:

PNG to JPG

Direct conversion might result in a black background. If the original has transparency, it's best to set a background color in the Conversion Tool.

JPG to WebP

This is the easiest; just convert directly. I tested a 2MB JPG which became about 600KB in WebP, with almost no visible difference in quality.

Batch Conversion

If you have many images, I recommend using command-line tools or batch processing software. Converting one by one takes too much time; I once converted 200 images and my hand got tired from clicking.

Real Case Study

Here is a real example. Our company website used to use all PNGs, and the homepage took 8 seconds to load. Later, I made these optimizations:

Converted all photos to WebP (reduced from 15MB to 4MB)
Kept logos and icons as PNG but compressed them
Added JPG fallback options

The result? Homepage load time dropped to 2 seconds, and our Google PageSpeed score rose from 45 to 92. My boss thought I upgraded the servers, but I just changed the image formats.

My Suggestions

Prioritize WebP for Web - Significant speed boost and better user experience.
Keep Originals - Back up before converting in case you need to re-process.
Test Compatibility - Check the effects on different devices after conversion.
Don't Over-Compress - Files get smaller, but if they are blurry, it's not worth it.

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Image Format Selection Guide - JPG vs PNG vs WebP