Most of us have been stuck at the amp error "Image size smaller than recommended size". To resolve this issue, we can use various methods. One of the ways is to get the warning removed from the amp section in Google Search console.
Here is how it can be resolved step by step:
We have amp blogs in which schema is written as shown in the above image (*small part of the schema). In the image section of schema, the sizes of the two image URLs are "652*434" and "305*290" respectively. The size "305*290" is not used for that blog post, which is used for another page. The size "652*434" is used as the banner image for the blog page.
We added around 25 amp blog post and the warning "Image size smaller than recommended size" is notified only for three blog posts. Which, in turn, means these three pages face some issue regarding images. We checked the problems, and the only difference is that the image URL provided is in a different order.
For the rest of 22 blog posts, the first image URL size was set to be "652*434" and the second one with "305*290". So that it didn't show any warning notifications. Whereas, for the three blog posts, we used to provide the first URL with image size is "305*290" and the second one with "652*434".
You need to change the order of image URL with priority to the bigger size. Always, keep a descending size order for the images. Then, go to Google webmaster and click on "Validate". Within two days, you will get the result notifying it as passed.