JPG to PNG

JPG stores images using lossy compression, which means some of the original pixel data was permanently discarded the moment the file was first saved, in exchange for a much smaller file. Converting that JPG to PNG doesn't reverse this — PNG can only losslessly preserve whatever pixel data currently exists in the file, artifacts and all. What you get is a PNG that won't lose any further quality on top of what the JPG already lost, which matters if the image is heading into another round of editing, layering or re-saving.

People typically reach for this conversion when a workflow or piece of software specifically requires a PNG input — certain design tools, print templates, or upload forms only accept PNG — or when they need to add transparency to an image that started as an opaque JPG by editing it further in image-editing software after conversion.

One practical trade-off: PNG files are usually larger than the source JPG for photographic content, sometimes considerably so, because PNG's lossless compression can't shrink photo-like gradients and noise as efficiently as JPG's lossy compression does. Expect the output file to be bigger, not smaller, than what you uploaded.