Images and preferred image types/formats are a common subject and, in some documentation, it was believed the PNG format was favoured by Google. While a JPEG file has compression, a PNG is lossless and also supports transparency.
In terms of quality and flexibility a PNG is therefore superior. As Google pushes the idea of making a better web through better content, it stands to reason that a PNG would be favored over a JPEG.
So is there a preferred format by Google?
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Transcription Below
This test was put together by Derek Booth. If you are doing client side work, one of the things you get into in the technical side of SEO when you are optimizing a site is making suggestions on making the the site better. One thing we looked at is if Google has a preference over PNG and JPG files. The idea is that PNG is considered as a superior image – it looks better in comparison compared to the compression of JPG images.
The idea behind this is that maybe the PNG files are better and Google likes it more because what they talk about is that you want a prettier and more authentic web. You want better content. If you want a better content and more unique things, PNG provides a better image and maybe Google prefers that. That is the genesis of this test.
Derek added the 5 page test pages, 4 were JPG and one was PNG which was the middle ranking one. Hilariously, it dropped to 5 which was a very unexpected result. We need to retest it and it is being retested right now. We are going to switch it.
The idea is that it is all PNGs and 1 JPG to see if the JPG would rise to the top and if there is a preference. I would not necessarily freak out and get rid of my PNGs but it anybody ever tells you that there is a specific file extension, you could probably bust that immediately. We are working on the next test to see if there is a ranking factor the other way. Probably not, it would be interesting if there is.
At a minimum, this image idea didn’t pan out and it is not anything to focus on in terms of changing things to PNGs.