It was believed that a PNG was preferred by Google as the image file of choice. In the 1st test, we tried 4 JPG and 1 PNG. In this test, we try 4 PNG and 1 JPG.
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Transcription Below
Part 2: PNG vs JPG Test
This was spearheaded by Derek Booth. We wanted to see if Google really cared about the type of image used. In the test, there were no movements whatsoever. What was interesting was that we saw some freshness update movement – some of the sites moved around.
When you do add something to a page, you will get a movement which was what you saw shifting around but the JPG page did not move up or down which is indicating that it is not a factor at all.
Google does not mind the file extension. Do not stress over your image file types would be my suggestion out of this one.