Finding the Quiz That Changed My Thinking
The quiz appeared in a web development Slack channel I am part of. Someone shared it with the comment 'this will humble you.' I rolled my eyes, but curiosity won out. The quiz section at QuizVertex covering image optimization specifically caught my attention. It asked questions about file formats, compression behavior, browser support timelines, and how platform re-compression affects image quality after upload.
I went in expecting to score well. I had been working with images professionally for the better part of a decade. But the quiz asked questions I had never actually sat down and looked up before, and when I answered from instinct, I got several of them wrong. More than wrong: I got them confidently wrong, which is the most expensive kind of wrong to have quietly embedded in a professional workflow.
Three Things I Was Completely Wrong About
The first gap was about PNG and photographs. I had a mental model where PNG meant quality and JPEG meant compression artifacts. So I was consistently saving photographs as PNG to preserve quality. What I did not fully understand was that PNG is lossless and excellent for screenshots and illustrations, but for photographs it creates enormous files with no perceptible quality advantage over a well-compressed JPEG. My product images were averaging 4.5MB as PNGs. The same images as JPEGs at 85% quality averaged 340KB.
The second gap was about WebP browser support. I had filed WebP away as an emerging format that needed JPEG fallbacks for a large portion of visitors. The quiz data showed me that WebP is now supported by over 97% of browsers worldwide as of 2025. I had been avoiding it based on information I had absorbed years earlier and never updated. I was making decisions from a state of the world that had not existed for several years.
The third gap was the most expensive: I had been letting my CMS auto-compress images without pre-optimizing them first. The platform was taking my already-suboptimal files and applying further compression with no quality control. Pre-optimizing before upload always produces better results than relying on platform auto-compression after the fact.
What I Did the Same Day
I started with my ten most-visited pages. Every PNG photograph got converted to WebP using the JPEG to WebP converter after first saving it as JPEG. Images that legitimately needed to stay as PNG for transparency reasons got run through the PNG compressor to at least reduce their file size as much as possible.
I also ran every image through the EXIF viewer to strip all embedded metadata before re-uploading. This removed between 20KB and 80KB from each image in camera metadata alone. Between the format conversions, the compression, and the metadata stripping, my top ten pages went from an average page weight of 7.2MB to 1.1MB.
Why Testing Your Knowledge Is Worth Five Minutes
The most valuable thing a well-designed quiz does is not teach you new information. It reveals what you think you know but have wrong. I had been running websites for eight years with the belief that PNG was the quality choice and WebP was experimental. Both of those beliefs were costing me real performance every single day. It took five minutes of focused questions to surface something that had been quietly running in the wrong direction for years.
If you have not recently audited your image format assumptions, it is worth doing. Check your most-used images with the EXIF viewer, look at whether you are using the right format for each use case, and ask yourself honestly when you last updated your understanding of browser support. You might find the same kinds of gaps I did. They are all very easy to fix once you know they are there.