>>I strongly recommend that you include the file extension (.jpg) in the field, why limit yourself to .jpg? png is used more and more, jpg may disappear over time.
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>PNG files are great, but they are lossless, often making their file sizes larger than that which is provided for by JPG, which is lossy, and can, therefore, have a much smaller file size without any significantly observable artefacts.
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>Both PNG and JPG have their place.

I don't disagree, but as storage is getting cheaper and cheaper, I notice that png is used more and more.