smush.it vs OptiPNG / pngcrush [closed]

Question

I'd like to see some online vs. offline image optimizers comparison numbers, namely Yahoo! Smush.it vs. OptiPNG or pngcrush.

How those things differ in speed and resulting image size, and what is the best choice?

Hillel

Answer 1

Very detailed and comprehensive comparison — with lots of tools and results on many different types of PNGs and optimizations:

http://css-ig.net/png-tools-overview

I think it's a much better source than PunyPNG's small comparison showing that their tool is best [partly at converting image formats rather than optimizing existing format] :)

Decca

wow, that site needs a chart or summary. – Unsuspected

Note that this overview is hosted on the pingo site (the pingo homepage is css-ig.net/pingo) so it's not exactly objective, either. I also question how legal pingo is, since that same overview says it's based on ECT -- which is GPL licensed -- but pingo is closed source. That's sketchy. – Diaphysis

Answer 2

I really don't know how reliable the information on this site is because they have their own compression service but take a look at the comparison in the URL: http://punypng.com/about/comparison

Ashtoreth

That one is not on the question, but thank you. – Hillel

They are not comparing to possibly more effective utils like pngcrush or pngout. – Ardithardme

No sample images, no performance data, no way to replicate results. – Danilodanio

Answer 3

I copied the following image:

And installed two of the tools you mentioned offline:

brew install optipng pngcrush

And compared image sizes using default settings with an online tool called reSmush.it:

879K feat-social-awareness.original.png
712K feat-social-awareness.optipng.png
700K feat-social-awareness.pngcrush.png
205K feat-social-awareness.resmushit.png

Speed of each tool was not measured for the above test. Subjectively they all felt about the same.

Comparing the images visually I was unable to see the difference between the original and the optimized versions created using the offline tools. In the case of reSmush.it, however, there was a noticeable loss in image fidelity which can be easily reproduced using their API (see example).

As a result, the above sizes are not an apples-to-apples comparison. More like apples-to-gorillas. So I went back and increased the reSmush.it quality to 100 by setting qlty=100 as specified in their API docs and got back the same lossy PNG as with the default settings.

So what's the best choice? Well, it depends…

• If compute resources are a major constraint consider using reSmush.it.
• If image fidelity is a concern don't use reSmush.it.
• If you use OptiPNG you're likely going to lose your original files (it overwrites by default).
• If you use pngcrush you're getting better compression compared to optipng without a noticeable loss in image fidelity.
• If you want lossy optimization similar to reSmush.it in an offline tool try pngquant.
• And if serving images over the wire under heavy bandwidth constraints consider a different image format altogether, such as Fabrice Bellard's BPG Image format.

Alcaic